Fix Issue #21: automatic calculation of alignment padding after lists

30 files changed, 630 insertions, 474 deletions

diff --git a/nexgb/dri2/dri2.go b/nexgb/dri2/dri2.go
index 6cec3d0..5ad0306 100644
--- a/nexgb/dri2/dri2.go
+++ b/nexgb/dri2/dri2.go
@@ -76,7 +76,7 @@ func (v AttachFormat) Bytes() []byte {
 	xgb.Put32(buf[b:], v.Format)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // AttachFormatListBytes writes a list of AttachFormat values to a byte slice.
@@ -281,7 +281,7 @@ func (v DRI2Buffer) Bytes() []byte {
 	xgb.Put32(buf[b:], v.Flags)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // DRI2BufferListBytes writes a list of DRI2Buffer values to a byte slice.
@@ -567,7 +567,7 @@ func connectReply(buf []byte) *ConnectReply {
 
 	v.AlignmentPad = make([]byte, (((int(v.DriverNameLength) + 3) & -4) - int(v.DriverNameLength)))
 	copy(v.AlignmentPad[:(((int(v.DriverNameLength)+3)&-4)-int(v.DriverNameLength))], buf[b:])
-	b += xgb.Pad(int((((int(v.DriverNameLength) + 3) & -4) - int(v.DriverNameLength))))
+	b += int((((int(v.DriverNameLength) + 3) & -4) - int(v.DriverNameLength)))
 
 	{
 		byteString := make([]byte, v.DeviceNameLength)
@@ -914,7 +914,6 @@ func getBuffersRequest(c *xgb.Conn, Drawable xproto.Drawable, Count uint32, Atta
 		xgb.Put32(buf[b:], Attachments[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
diff --git a/nexgb/examples/randr/main.go b/nexgb/examples/randr/main.go
index 414ef8d..ac6fb7a 100644
--- a/nexgb/examples/randr/main.go
+++ b/nexgb/examples/randr/main.go
@@ -63,7 +63,7 @@ func main() {
 		if err != nil {
 			log.Fatal(err)
 		}
-		fmt.Printf("X: %d, Y: %d, Width: %d, Height: %d\n",
+		fmt.Printf("%v, X: %d, Y: %d, Width: %d, Height: %d\n",
 			info.X, info.Y, info.Width, info.Height)
 	}
 
diff --git a/nexgb/glx/glx.go b/nexgb/glx/glx.go
index 979d577..0951765 100644
--- a/nexgb/glx/glx.go
+++ b/nexgb/glx/glx.go
@@ -1097,7 +1097,6 @@ func areTexturesResidentReply(buf []byte) *AreTexturesResidentReply {
 		}
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -1128,7 +1127,6 @@ func areTexturesResidentRequest(c *xgb.Conn, ContextTag ContextTag, N int32, Tex
 		xgb.Put32(buf[b:], Textures[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1192,7 +1190,6 @@ func changeDrawableAttributesRequest(c *xgb.Conn, Drawable Drawable, NumAttribs
 		xgb.Put32(buf[b:], Attribs[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1256,7 +1253,7 @@ func clientInfoRequest(c *xgb.Conn, MajorVersion uint32, MinorVersion uint32, St
 	b += 4
 
 	copy(buf[b:], String[:StrLen])
-	b += xgb.Pad(int(StrLen))
+	b += int(StrLen)
 
 	return buf
 }
@@ -1475,7 +1472,6 @@ func createContextAttribsARBRequest(c *xgb.Conn, Context Context, Fbconfig Fbcon
 		xgb.Put32(buf[b:], Attribs[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1685,7 +1681,6 @@ func createPbufferRequest(c *xgb.Conn, Screen uint32, Fbconfig Fbconfig, Pbuffer
 		xgb.Put32(buf[b:], Attribs[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1758,7 +1753,6 @@ func createPixmapRequest(c *xgb.Conn, Screen uint32, Fbconfig Fbconfig, Pixmap x
 		xgb.Put32(buf[b:], Attribs[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1831,7 +1825,6 @@ func createWindowRequest(c *xgb.Conn, Screen uint32, Fbconfig Fbconfig, Window x
 		xgb.Put32(buf[b:], Attribs[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1956,7 +1949,6 @@ func deleteQueriesARBRequest(c *xgb.Conn, ContextTag ContextTag, N int32, Ids []
 		xgb.Put32(buf[b:], Ids[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -2020,7 +2012,6 @@ func deleteTexturesRequest(c *xgb.Conn, ContextTag ContextTag, N int32, Textures
 		xgb.Put32(buf[b:], Textures[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -2714,7 +2705,6 @@ func genQueriesARBReply(buf []byte) *GenQueriesARBReply {
 		v.Data[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -2812,7 +2802,6 @@ func genTexturesReply(buf []byte) *GenTexturesReply {
 		v.Data[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -2929,7 +2918,6 @@ func getBooleanvReply(buf []byte) *GetBooleanvReply {
 		}
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -3027,7 +3015,6 @@ func getClipPlaneReply(buf []byte) *GetClipPlaneReply {
 		v.Data[i] = Float64(xgb.Get64(buf[b:]))
 		b += 8
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -3129,7 +3116,7 @@ func getColorTableReply(buf []byte) *GetColorTableReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -3251,7 +3238,6 @@ func getColorTableParameterfvReply(buf []byte) *GetColorTableParameterfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -3363,7 +3349,6 @@ func getColorTableParameterivReply(buf []byte) *GetColorTableParameterivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -3468,7 +3453,7 @@ func getCompressedTexImageARBReply(buf []byte) *GetCompressedTexImageARBReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -3577,7 +3562,7 @@ func getConvolutionFilterReply(buf []byte) *GetConvolutionFilterReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -3699,7 +3684,6 @@ func getConvolutionParameterfvReply(buf []byte) *GetConvolutionParameterfvReply
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -3811,7 +3795,6 @@ func getConvolutionParameterivReply(buf []byte) *GetConvolutionParameterivReply
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -3923,7 +3906,6 @@ func getDoublevReply(buf []byte) *GetDoublevReply {
 		v.Data[i] = Float64(xgb.Get64(buf[b:]))
 		b += 8
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4025,7 +4007,6 @@ func getDrawableAttributesReply(buf []byte) *GetDrawableAttributesReply {
 		v.Attribs[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4216,7 +4197,6 @@ func getFBConfigsReply(buf []byte) *GetFBConfigsReply {
 		v.PropertyList[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4322,7 +4302,6 @@ func getFloatvReply(buf []byte) *GetFloatvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4424,7 +4403,7 @@ func getHistogramReply(buf []byte) *GetHistogramReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -4553,7 +4532,6 @@ func getHistogramParameterfvReply(buf []byte) *GetHistogramParameterfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4665,7 +4643,6 @@ func getHistogramParameterivReply(buf []byte) *GetHistogramParameterivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4777,7 +4754,6 @@ func getIntegervReply(buf []byte) *GetIntegervReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4886,7 +4862,6 @@ func getLightfvReply(buf []byte) *GetLightfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4998,7 +4973,6 @@ func getLightivReply(buf []byte) *GetLightivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -5110,7 +5084,6 @@ func getMapdvReply(buf []byte) *GetMapdvReply {
 		v.Data[i] = Float64(xgb.Get64(buf[b:]))
 		b += 8
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -5222,7 +5195,6 @@ func getMapfvReply(buf []byte) *GetMapfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -5334,7 +5306,6 @@ func getMapivReply(buf []byte) *GetMapivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -5446,7 +5417,6 @@ func getMaterialfvReply(buf []byte) *GetMaterialfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -5558,7 +5528,6 @@ func getMaterialivReply(buf []byte) *GetMaterialivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -5656,7 +5625,7 @@ func getMinmaxReply(buf []byte) *GetMinmaxReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -5785,7 +5754,6 @@ func getMinmaxParameterfvReply(buf []byte) *GetMinmaxParameterfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -5897,7 +5865,6 @@ func getMinmaxParameterivReply(buf []byte) *GetMinmaxParameterivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -6009,7 +5976,6 @@ func getPixelMapfvReply(buf []byte) *GetPixelMapfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -6118,7 +6084,6 @@ func getPixelMapuivReply(buf []byte) *GetPixelMapuivReply {
 		v.Data[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -6227,7 +6192,6 @@ func getPixelMapusvReply(buf []byte) *GetPixelMapusvReply {
 		v.Data[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -6322,7 +6286,7 @@ func getPolygonStippleReply(buf []byte) *GetPolygonStippleReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -6435,7 +6399,6 @@ func getQueryObjectivARBReply(buf []byte) *GetQueryObjectivARBReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -6547,7 +6510,6 @@ func getQueryObjectuivARBReply(buf []byte) *GetQueryObjectuivARBReply {
 		v.Data[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -6659,7 +6621,6 @@ func getQueryivARBReply(buf []byte) *GetQueryivARBReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -6768,7 +6729,7 @@ func getSeparableFilterReply(buf []byte) *GetSeparableFilterReply {
 
 	v.RowsAndCols = make([]byte, (int(v.Length) * 4))
 	copy(v.RowsAndCols[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -6995,7 +6956,6 @@ func getTexEnvfvReply(buf []byte) *GetTexEnvfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -7107,7 +7067,6 @@ func getTexEnvivReply(buf []byte) *GetTexEnvivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -7219,7 +7178,6 @@ func getTexGendvReply(buf []byte) *GetTexGendvReply {
 		v.Data[i] = Float64(xgb.Get64(buf[b:]))
 		b += 8
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -7331,7 +7289,6 @@ func getTexGenfvReply(buf []byte) *GetTexGenfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -7443,7 +7400,6 @@ func getTexGenivReply(buf []byte) *GetTexGenivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -7556,7 +7512,7 @@ func getTexImageReply(buf []byte) *GetTexImageReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -7681,7 +7637,6 @@ func getTexLevelParameterfvReply(buf []byte) *GetTexLevelParameterfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -7796,7 +7751,6 @@ func getTexLevelParameterivReply(buf []byte) *GetTexLevelParameterivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -7911,7 +7865,6 @@ func getTexParameterfvReply(buf []byte) *GetTexParameterfvReply {
 		v.Data[i] = Float32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -8023,7 +7976,6 @@ func getTexParameterivReply(buf []byte) *GetTexParameterivReply {
 		v.Data[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -8132,7 +8084,6 @@ func getVisualConfigsReply(buf []byte) *GetVisualConfigsReply {
 		v.PropertyList[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -8979,7 +8930,6 @@ func queryContextReply(buf []byte) *QueryContextReply {
 		v.Attribs[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -9368,7 +9318,7 @@ func readPixelsReply(buf []byte) *ReadPixelsReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -9480,7 +9430,7 @@ func renderRequest(c *xgb.Conn, ContextTag ContextTag, Data []byte) []byte {
 	b += 4
 
 	copy(buf[b:], Data[:len(Data)])
-	b += xgb.Pad(int(len(Data)))
+	b += int(len(Data))
 
 	return buf
 }
@@ -9547,7 +9497,7 @@ func renderLargeRequest(c *xgb.Conn, ContextTag ContextTag, RequestNum uint16, R
 	b += 4
 
 	copy(buf[b:], Data[:DataLen])
-	b += xgb.Pad(int(DataLen))
+	b += int(DataLen)
 
 	return buf
 }
@@ -9632,7 +9582,6 @@ func renderModeReply(buf []byte) *RenderModeReply {
 		v.Data[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -9788,13 +9737,12 @@ func setClientInfo2ARBRequest(c *xgb.Conn, MajorVersion uint32, MinorVersion uin
 		xgb.Put32(buf[b:], GlVersions[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	copy(buf[b:], GlExtensionString[:GlStrLen])
-	b += xgb.Pad(int(GlStrLen))
+	b += int(GlStrLen)
 
 	copy(buf[b:], GlxExtensionString[:GlxStrLen])
-	b += xgb.Pad(int(GlxStrLen))
+	b += int(GlxStrLen)
 
 	return buf
 }
@@ -9867,13 +9815,12 @@ func setClientInfoARBRequest(c *xgb.Conn, MajorVersion uint32, MinorVersion uint
 		xgb.Put32(buf[b:], GlVersions[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	copy(buf[b:], GlExtensionString[:GlStrLen])
-	b += xgb.Pad(int(GlStrLen))
+	b += int(GlStrLen)
 
 	copy(buf[b:], GlxExtensionString[:GlxStrLen])
-	b += xgb.Pad(int(GlxStrLen))
+	b += int(GlxStrLen)
 
 	return buf
 }
@@ -10059,7 +10006,7 @@ func vendorPrivateRequest(c *xgb.Conn, VendorCode uint32, ContextTag ContextTag,
 	b += 4
 
 	copy(buf[b:], Data[:len(Data)])
-	b += xgb.Pad(int(len(Data)))
+	b += int(len(Data))
 
 	return buf
 }
@@ -10131,11 +10078,11 @@ func vendorPrivateWithReplyReply(buf []byte) *VendorPrivateWithReplyReply {
 
 	v.Data1 = make([]byte, 24)
 	copy(v.Data1[:24], buf[b:])
-	b += xgb.Pad(int(24))
+	b += int(24)
 
 	v.Data2 = make([]byte, (int(v.Length) * 4))
 	copy(v.Data2[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -10163,7 +10110,7 @@ func vendorPrivateWithReplyRequest(c *xgb.Conn, VendorCode uint32, ContextTag Co
 	b += 4
 
 	copy(buf[b:], Data[:len(Data)])
-	b += xgb.Pad(int(len(Data)))
+	b += int(len(Data))
 
 	return buf
 }
diff --git a/nexgb/randr/randr.go b/nexgb/randr/randr.go
index db45a23..20dc62a 100644
--- a/nexgb/randr/randr.go
+++ b/nexgb/randr/randr.go
@@ -331,7 +331,7 @@ func (v CrtcChange) Bytes() []byte {
 	xgb.Put16(buf[b:], v.Height)
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // CrtcChangeListBytes writes a list of CrtcChange values to a byte slice.
@@ -489,7 +489,7 @@ func (v ModeInfo) Bytes() []byte {
 	xgb.Put32(buf[b:], v.ModeFlags)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // ModeInfoListBytes writes a list of ModeInfo values to a byte slice.
@@ -504,6 +504,15 @@ func ModeInfoListBytes(buf []byte, list []ModeInfo) int {
 	return xgb.Pad(b)
 }
 
+const (
+	NotifyCrtcChange       = 0
+	NotifyOutputChange     = 1
+	NotifyOutputProperty   = 2
+	NotifyProviderChange   = 3
+	NotifyProviderProperty = 4
+	NotifyResourceChange   = 5
+)
+
 // Notify is the event number for a NotifyEvent.
 const Notify = 1
 
@@ -572,15 +581,6 @@ func init() {
 	xgb.NewExtEventFuncs["RANDR"][1] = NotifyEventNew
 }
 
-const (
-	NotifyCrtcChange       = 0
-	NotifyOutputChange     = 1
-	NotifyOutputProperty   = 2
-	NotifyProviderChange   = 3
-	NotifyProviderProperty = 4
-	NotifyResourceChange   = 5
-)
-
 // NotifyDataUnion is a represention of the NotifyDataUnion union type.
 // Note that to *create* a Union, you should *never* create
 // this struct directly (unless you know what you're doing).
@@ -1034,7 +1034,7 @@ func (v OutputChange) Bytes() []byte {
 	buf[b] = v.SubpixelOrder
 	b += 1
 
-	return buf
+	return buf[:b]
 }
 
 // OutputChangeListBytes writes a list of OutputChange values to a byte slice.
@@ -1114,7 +1114,7 @@ func (v OutputProperty) Bytes() []byte {
 
 	b += 11 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // OutputPropertyListBytes writes a list of OutputProperty values to a byte slice.
@@ -1197,7 +1197,7 @@ func (v ProviderChange) Bytes() []byte {
 
 	b += 16 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // ProviderChangeListBytes writes a list of ProviderChange values to a byte slice.
@@ -1277,7 +1277,7 @@ func (v ProviderProperty) Bytes() []byte {
 
 	b += 11 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // ProviderPropertyListBytes writes a list of ProviderProperty values to a byte slice.
@@ -1309,7 +1309,6 @@ func RefreshRatesRead(buf []byte, v *RefreshRates) int {
 		v.Rates[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	return b
 }
@@ -1336,9 +1335,8 @@ func (v RefreshRates) Bytes() []byte {
 		xgb.Put16(buf[b:], v.Rates[i])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
-	return buf
+	return buf[:b]
 }
 
 // RefreshRatesListBytes writes a list of RefreshRates values to a byte slice.
@@ -1406,7 +1404,7 @@ func (v ResourceChange) Bytes() []byte {
 
 	b += 20 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // ResourceChangeListBytes writes a list of ResourceChange values to a byte slice.
@@ -1621,7 +1619,7 @@ func (v ScreenSize) Bytes() []byte {
 	xgb.Put16(buf[b:], v.Mheight)
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // ScreenSizeListBytes writes a list of ScreenSize values to a byte slice.
@@ -1802,7 +1800,7 @@ func changeOutputPropertyRequest(c *xgb.Conn, Output Output, Property xproto.Ato
 	b += 4
 
 	copy(buf[b:], Data[:((int(NumUnits)*int(Format))/8)])
-	b += xgb.Pad(int(((int(NumUnits) * int(Format)) / 8)))
+	b += int(((int(NumUnits) * int(Format)) / 8))
 
 	return buf
 }
@@ -1877,7 +1875,7 @@ func changeProviderPropertyRequest(c *xgb.Conn, Provider Provider, Property xpro
 	b += 4
 
 	copy(buf[b:], Data[:(int(NumItems)*(int(Format)/8))])
-	b += xgb.Pad(int((int(NumItems) * (int(Format) / 8))))
+	b += int((int(NumItems) * (int(Format) / 8)))
 
 	return buf
 }
@@ -1957,7 +1955,6 @@ func configureOutputPropertyRequest(c *xgb.Conn, Output Output, Property xproto.
 		xgb.Put32(buf[b:], uint32(Values[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -2037,7 +2034,6 @@ func configureProviderPropertyRequest(c *xgb.Conn, Provider Provider, Property x
 		xgb.Put32(buf[b:], uint32(Values[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -2137,7 +2133,7 @@ func createModeRequest(c *xgb.Conn, Window xproto.Window, ModeInfo ModeInfo, Nam
 	}
 
 	copy(buf[b:], Name[:len(Name)])
-	b += xgb.Pad(int(len(Name)))
+	b += int(len(Name))
 
 	return buf
 }
@@ -2405,9 +2401,11 @@ type GetCrtcGammaReply struct {
 	// padding: 1 bytes
 	Size uint16
 	// padding: 22 bytes
-	Red   []uint16 // size: xgb.Pad((int(Size) * 2))
+	Red []uint16 // size: xgb.Pad((int(Size) * 2))
+	// alignment gap to multiple of 2
 	Green []uint16 // size: xgb.Pad((int(Size) * 2))
-	Blue  []uint16 // size: xgb.Pad((int(Size) * 2))
+	// alignment gap to multiple of 2
+	Blue []uint16 // size: xgb.Pad((int(Size) * 2))
 }
 
 // Reply blocks and returns the reply data for a GetCrtcGamma request.
@@ -2445,21 +2443,22 @@ func getCrtcGammaReply(buf []byte) *GetCrtcGammaReply {
 		v.Red[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 1) & ^1 // alignment gap
 
 	v.Green = make([]uint16, v.Size)
 	for i := 0; i < int(v.Size); i++ {
 		v.Green[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 1) & ^1 // alignment gap
 
 	v.Blue = make([]uint16, v.Size)
 	for i := 0; i < int(v.Size); i++ {
 		v.Blue[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -2620,7 +2619,8 @@ type GetCrtcInfoReply struct {
 	NumOutputs         uint16
 	NumPossibleOutputs uint16
 	Outputs            []Output // size: xgb.Pad((int(NumOutputs) * 4))
-	Possible           []Output // size: xgb.Pad((int(NumPossibleOutputs) * 4))
+	// alignment gap to multiple of 4
+	Possible []Output // size: xgb.Pad((int(NumPossibleOutputs) * 4))
 }
 
 // Reply blocks and returns the reply data for a GetCrtcInfo request.
@@ -2684,14 +2684,14 @@ func getCrtcInfoReply(buf []byte) *GetCrtcInfoReply {
 		v.Outputs[i] = Output(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Possible = make([]Output, v.NumPossibleOutputs)
 	for i := 0; i < int(v.NumPossibleOutputs); i++ {
 		v.Possible[i] = Output(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -2762,10 +2762,12 @@ type GetCrtcTransformReply struct {
 	PendingNparams    uint16
 	CurrentLen        uint16
 	CurrentNparams    uint16
-	PendingFilterName string         // size: xgb.Pad((int(PendingLen) * 1))
+	PendingFilterName string // size: xgb.Pad((int(PendingLen) * 1))
+	// alignment gap to multiple of 4
 	PendingParams     []render.Fixed // size: xgb.Pad((int(PendingNparams) * 4))
 	CurrentFilterName string         // size: xgb.Pad((int(CurrentLen) * 1))
-	CurrentParams     []render.Fixed // size: xgb.Pad((int(CurrentNparams) * 4))
+	// alignment gap to multiple of 4
+	CurrentParams []render.Fixed // size: xgb.Pad((int(CurrentNparams) * 4))
 }
 
 // Reply blocks and returns the reply data for a GetCrtcTransform request.
@@ -2829,12 +2831,13 @@ func getCrtcTransformReply(buf []byte) *GetCrtcTransformReply {
 		b += int(v.PendingLen)
 	}
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.PendingParams = make([]render.Fixed, v.PendingNparams)
 	for i := 0; i < int(v.PendingNparams); i++ {
 		v.PendingParams[i] = render.Fixed(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	{
 		byteString := make([]byte, v.CurrentLen)
@@ -2843,12 +2846,13 @@ func getCrtcTransformReply(buf []byte) *GetCrtcTransformReply {
 		b += int(v.CurrentLen)
 	}
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.CurrentParams = make([]render.Fixed, v.CurrentNparams)
 	for i := 0; i < int(v.CurrentNparams); i++ {
 		v.CurrentParams[i] = render.Fixed(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -2918,10 +2922,12 @@ type GetOutputInfoReply struct {
 	NumPreferred  uint16
 	NumClones     uint16
 	NameLen       uint16
-	Crtcs         []Crtc   // size: xgb.Pad((int(NumCrtcs) * 4))
-	Modes         []Mode   // size: xgb.Pad((int(NumModes) * 4))
-	Clones        []Output // size: xgb.Pad((int(NumClones) * 4))
-	Name          []byte   // size: xgb.Pad((int(NameLen) * 1))
+	Crtcs         []Crtc // size: xgb.Pad((int(NumCrtcs) * 4))
+	// alignment gap to multiple of 4
+	Modes []Mode // size: xgb.Pad((int(NumModes) * 4))
+	// alignment gap to multiple of 4
+	Clones []Output // size: xgb.Pad((int(NumClones) * 4))
+	Name   []byte   // size: xgb.Pad((int(NameLen) * 1))
 }
 
 // Reply blocks and returns the reply data for a GetOutputInfo request.
@@ -2988,25 +2994,26 @@ func getOutputInfoReply(buf []byte) *GetOutputInfoReply {
 		v.Crtcs[i] = Crtc(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Modes = make([]Mode, v.NumModes)
 	for i := 0; i < int(v.NumModes); i++ {
 		v.Modes[i] = Mode(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Clones = make([]Output, v.NumClones)
 	for i := 0; i < int(v.NumClones); i++ {
 		v.Clones[i] = Output(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	v.Name = make([]byte, v.NameLen)
 	copy(v.Name[:v.NameLen], buf[b:])
-	b += xgb.Pad(int(v.NameLen))
+	b += int(v.NameLen)
 
 	return v
 }
@@ -3202,7 +3209,7 @@ func getOutputPropertyReply(buf []byte) *GetOutputPropertyReply {
 
 	v.Data = make([]byte, (int(v.NumItems) * (int(v.Format) / 8)))
 	copy(v.Data[:(int(v.NumItems)*(int(v.Format)/8))], buf[b:])
-	b += xgb.Pad(int((int(v.NumItems) * (int(v.Format) / 8))))
+	b += int((int(v.NumItems) * (int(v.Format) / 8)))
 
 	return v
 }
@@ -3433,11 +3440,14 @@ type GetProviderInfoReply struct {
 	NumAssociatedProviders uint16
 	NameLen                uint16
 	// padding: 8 bytes
-	Crtcs                []Crtc     // size: xgb.Pad((int(NumCrtcs) * 4))
-	Outputs              []Output   // size: xgb.Pad((int(NumOutputs) * 4))
-	AssociatedProviders  []Provider // size: xgb.Pad((int(NumAssociatedProviders) * 4))
-	AssociatedCapability []uint32   // size: xgb.Pad((int(NumAssociatedProviders) * 4))
-	Name                 string     // size: xgb.Pad((int(NameLen) * 1))
+	Crtcs []Crtc // size: xgb.Pad((int(NumCrtcs) * 4))
+	// alignment gap to multiple of 4
+	Outputs []Output // size: xgb.Pad((int(NumOutputs) * 4))
+	// alignment gap to multiple of 4
+	AssociatedProviders []Provider // size: xgb.Pad((int(NumAssociatedProviders) * 4))
+	// alignment gap to multiple of 4
+	AssociatedCapability []uint32 // size: xgb.Pad((int(NumAssociatedProviders) * 4))
+	Name                 string   // size: xgb.Pad((int(NameLen) * 1))
 }
 
 // Reply blocks and returns the reply data for a GetProviderInfo request.
@@ -3491,28 +3501,30 @@ func getProviderInfoReply(buf []byte) *GetProviderInfoReply {
 		v.Crtcs[i] = Crtc(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Outputs = make([]Output, v.NumOutputs)
 	for i := 0; i < int(v.NumOutputs); i++ {
 		v.Outputs[i] = Output(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.AssociatedProviders = make([]Provider, v.NumAssociatedProviders)
 	for i := 0; i < int(v.NumAssociatedProviders); i++ {
 		v.AssociatedProviders[i] = Provider(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.AssociatedCapability = make([]uint32, v.NumAssociatedProviders)
 	for i := 0; i < int(v.NumAssociatedProviders); i++ {
 		v.AssociatedCapability[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	{
 		byteString := make([]byte, v.NameLen)
@@ -3627,7 +3639,7 @@ func getProviderPropertyReply(buf []byte) *GetProviderPropertyReply {
 
 	v.Data = make([]byte, (int(v.NumItems) * (int(v.Format) / 8)))
 	copy(v.Data[:(int(v.NumItems)*(int(v.Format)/8))], buf[b:])
-	b += xgb.Pad(int((int(v.NumItems) * (int(v.Format) / 8))))
+	b += int((int(v.NumItems) * (int(v.Format) / 8)))
 
 	return v
 }
@@ -3758,7 +3770,6 @@ func getProvidersReply(buf []byte) *GetProvidersReply {
 		v.Providers[i] = Provider(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -3826,7 +3837,8 @@ type GetScreenInfoReply struct {
 	Rate            uint16
 	NInfo           uint16
 	// padding: 2 bytes
-	Sizes []ScreenSize   // size: xgb.Pad((int(NSizes) * 8))
+	Sizes []ScreenSize // size: xgb.Pad((int(NSizes) * 8))
+	// alignment gap to multiple of 2
 	Rates []RefreshRates // size: RefreshRatesListSize(Rates)
 }
 
@@ -3885,6 +3897,8 @@ func getScreenInfoReply(buf []byte) *GetScreenInfoReply {
 	v.Sizes = make([]ScreenSize, v.NSizes)
 	b += ScreenSizeReadList(buf[b:], v.Sizes)
 
+	b = (b + 1) & ^1 // alignment gap
+
 	v.Rates = make([]RefreshRates, (int(v.NInfo) - int(v.NSizes)))
 	b += RefreshRatesReadList(buf[b:], v.Rates)
 
@@ -3952,10 +3966,12 @@ type GetScreenResourcesReply struct {
 	NumModes        uint16
 	NamesLen        uint16
 	// padding: 8 bytes
-	Crtcs   []Crtc     // size: xgb.Pad((int(NumCrtcs) * 4))
-	Outputs []Output   // size: xgb.Pad((int(NumOutputs) * 4))
-	Modes   []ModeInfo // size: xgb.Pad((int(NumModes) * 32))
-	Names   []byte     // size: xgb.Pad((int(NamesLen) * 1))
+	Crtcs []Crtc // size: xgb.Pad((int(NumCrtcs) * 4))
+	// alignment gap to multiple of 4
+	Outputs []Output // size: xgb.Pad((int(NumOutputs) * 4))
+	// alignment gap to multiple of 4
+	Modes []ModeInfo // size: xgb.Pad((int(NumModes) * 32))
+	Names []byte     // size: xgb.Pad((int(NamesLen) * 1))
 }
 
 // Reply blocks and returns the reply data for a GetScreenResources request.
@@ -4008,21 +4024,23 @@ func getScreenResourcesReply(buf []byte) *GetScreenResourcesReply {
 		v.Crtcs[i] = Crtc(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Outputs = make([]Output, v.NumOutputs)
 	for i := 0; i < int(v.NumOutputs); i++ {
 		v.Outputs[i] = Output(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Modes = make([]ModeInfo, v.NumModes)
 	b += ModeInfoReadList(buf[b:], v.Modes)
 
 	v.Names = make([]byte, v.NamesLen)
 	copy(v.Names[:v.NamesLen], buf[b:])
-	b += xgb.Pad(int(v.NamesLen))
+	b += int(v.NamesLen)
 
 	return v
 }
@@ -4088,10 +4106,12 @@ type GetScreenResourcesCurrentReply struct {
 	NumModes        uint16
 	NamesLen        uint16
 	// padding: 8 bytes
-	Crtcs   []Crtc     // size: xgb.Pad((int(NumCrtcs) * 4))
-	Outputs []Output   // size: xgb.Pad((int(NumOutputs) * 4))
-	Modes   []ModeInfo // size: xgb.Pad((int(NumModes) * 32))
-	Names   []byte     // size: xgb.Pad((int(NamesLen) * 1))
+	Crtcs []Crtc // size: xgb.Pad((int(NumCrtcs) * 4))
+	// alignment gap to multiple of 4
+	Outputs []Output // size: xgb.Pad((int(NumOutputs) * 4))
+	// alignment gap to multiple of 4
+	Modes []ModeInfo // size: xgb.Pad((int(NumModes) * 32))
+	Names []byte     // size: xgb.Pad((int(NamesLen) * 1))
 }
 
 // Reply blocks and returns the reply data for a GetScreenResourcesCurrent request.
@@ -4144,21 +4164,23 @@ func getScreenResourcesCurrentReply(buf []byte) *GetScreenResourcesCurrentReply
 		v.Crtcs[i] = Crtc(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Outputs = make([]Output, v.NumOutputs)
 	for i := 0; i < int(v.NumOutputs); i++ {
 		v.Outputs[i] = Output(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Modes = make([]ModeInfo, v.NumModes)
 	b += ModeInfoReadList(buf[b:], v.Modes)
 
 	v.Names = make([]byte, v.NamesLen)
 	copy(v.Names[:v.NamesLen], buf[b:])
-	b += xgb.Pad(int(v.NamesLen))
+	b += int(v.NamesLen)
 
 	return v
 }
@@ -4360,7 +4382,6 @@ func listOutputPropertiesReply(buf []byte) *ListOutputPropertiesReply {
 		v.Atoms[i] = xproto.Atom(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4459,7 +4480,6 @@ func listProviderPropertiesReply(buf []byte) *ListProviderPropertiesReply {
 		v.Atoms[i] = xproto.Atom(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4578,7 +4598,6 @@ func queryOutputPropertyReply(buf []byte) *QueryOutputPropertyReply {
 		v.ValidValues[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -4700,7 +4719,6 @@ func queryProviderPropertyReply(buf []byte) *QueryProviderPropertyReply {
 		v.ValidValues[i] = int32(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -5001,7 +5019,6 @@ func setCrtcConfigRequest(c *xgb.Conn, Crtc Crtc, Timestamp xproto.Timestamp, Co
 		xgb.Put32(buf[b:], uint32(Outputs[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -5042,7 +5059,7 @@ func (cook SetCrtcGammaCookie) Check() error {
 // Write request to wire for SetCrtcGamma
 // setCrtcGammaRequest writes a SetCrtcGamma request to a byte slice.
 func setCrtcGammaRequest(c *xgb.Conn, Crtc Crtc, Size uint16, Red []uint16, Green []uint16, Blue []uint16) []byte {
-	size := xgb.Pad((((12 + xgb.Pad((int(Size) * 2))) + xgb.Pad((int(Size) * 2))) + xgb.Pad((int(Size) * 2))))
+	size := xgb.Pad((((((12 + xgb.Pad((int(Size) * 2))) + 2) + xgb.Pad((int(Size) * 2))) + 2) + xgb.Pad((int(Size) * 2))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -5052,7 +5069,7 @@ func setCrtcGammaRequest(c *xgb.Conn, Crtc Crtc, Size uint16, Red []uint16, Gree
 	buf[b] = 24 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put32(buf[b:], uint32(Crtc))
@@ -5067,21 +5084,24 @@ func setCrtcGammaRequest(c *xgb.Conn, Crtc Crtc, Size uint16, Red []uint16, Gree
 		xgb.Put16(buf[b:], Red[i])
 		b += 2
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 1) & ^1 // alignment gap
 
 	for i := 0; i < int(Size); i++ {
 		xgb.Put16(buf[b:], Green[i])
 		b += 2
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 1) & ^1 // alignment gap
 
 	for i := 0; i < int(Size); i++ {
 		xgb.Put16(buf[b:], Blue[i])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // SetCrtcTransformCookie is a cookie used only for SetCrtcTransform requests.
@@ -5120,7 +5140,7 @@ func (cook SetCrtcTransformCookie) Check() error {
 // Write request to wire for SetCrtcTransform
 // setCrtcTransformRequest writes a SetCrtcTransform request to a byte slice.
 func setCrtcTransformRequest(c *xgb.Conn, Crtc Crtc, Transform render.Transform, FilterLen uint16, FilterName string, FilterParams []render.Fixed) []byte {
-	size := xgb.Pad(((48 + xgb.Pad((int(FilterLen) * 1))) + xgb.Pad((len(FilterParams) * 4))))
+	size := xgb.Pad((((48 + xgb.Pad((int(FilterLen) * 1))) + 4) + xgb.Pad((len(FilterParams) * 4))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -5130,7 +5150,7 @@ func setCrtcTransformRequest(c *xgb.Conn, Crtc Crtc, Transform render.Transform,
 	buf[b] = 26 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put32(buf[b:], uint32(Crtc))
@@ -5148,15 +5168,18 @@ func setCrtcTransformRequest(c *xgb.Conn, Crtc Crtc, Transform render.Transform,
 	b += 2 // padding
 
 	copy(buf[b:], FilterName[:FilterLen])
-	b += xgb.Pad(int(FilterLen))
+	b += int(FilterLen)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	for i := 0; i < int(len(FilterParams)); i++ {
 		xgb.Put32(buf[b:], uint32(FilterParams[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // SetOutputPrimaryCookie is a cookie used only for SetOutputPrimary requests.
diff --git a/nexgb/record/record.go b/nexgb/record/record.go
index 3777422..30be090 100644
--- a/nexgb/record/record.go
+++ b/nexgb/record/record.go
@@ -133,7 +133,7 @@ func (v ClientInfo) Bytes() []byte {
 
 	b += RangeListBytes(buf[b:], v.Ranges)
 
-	return buf
+	return buf[:b]
 }
 
 // ClientInfoListBytes writes a list of ClientInfo values to a byte slice.
@@ -222,7 +222,7 @@ func (v ExtRange) Bytes() []byte {
 		b += len(structBytes)
 	}
 
-	return buf
+	return buf[:b]
 }
 
 // ExtRangeListBytes writes a list of ExtRange values to a byte slice.
@@ -368,7 +368,7 @@ func (v Range) Bytes() []byte {
 	}
 	b += 1
 
-	return buf
+	return buf[:b]
 }
 
 // RangeListBytes writes a list of Range values to a byte slice.
@@ -422,7 +422,7 @@ func (v Range16) Bytes() []byte {
 	xgb.Put16(buf[b:], v.Last)
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // Range16ListBytes writes a list of Range16 values to a byte slice.
@@ -476,7 +476,7 @@ func (v Range8) Bytes() []byte {
 	buf[b] = v.Last
 	b += 1
 
-	return buf
+	return buf[:b]
 }
 
 // Range8ListBytes writes a list of Range8 values to a byte slice.
@@ -551,7 +551,7 @@ func (cook CreateContextCookie) Check() error {
 // Write request to wire for CreateContext
 // createContextRequest writes a CreateContext request to a byte slice.
 func createContextRequest(c *xgb.Conn, Context Context, ElementHeader ElementHeader, NumClientSpecs uint32, NumRanges uint32, ClientSpecs []ClientSpec, Ranges []Range) []byte {
-	size := xgb.Pad(((20 + xgb.Pad((int(NumClientSpecs) * 4))) + xgb.Pad((int(NumRanges) * 24))))
+	size := xgb.Pad((((20 + xgb.Pad((int(NumClientSpecs) * 4))) + 4) + xgb.Pad((int(NumRanges) * 24))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -561,7 +561,7 @@ func createContextRequest(c *xgb.Conn, Context Context, ElementHeader ElementHea
 	buf[b] = 1 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put32(buf[b:], uint32(Context))
@@ -582,11 +582,14 @@ func createContextRequest(c *xgb.Conn, Context Context, ElementHeader ElementHea
 		xgb.Put32(buf[b:], uint32(ClientSpecs[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	b += RangeListBytes(buf[b:], Ranges)
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // DisableContextCookie is a cookie used only for DisableContext requests.
@@ -737,7 +740,7 @@ func enableContextReply(buf []byte) *EnableContextReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -1057,7 +1060,7 @@ func (cook RegisterClientsCookie) Check() error {
 // Write request to wire for RegisterClients
 // registerClientsRequest writes a RegisterClients request to a byte slice.
 func registerClientsRequest(c *xgb.Conn, Context Context, ElementHeader ElementHeader, NumClientSpecs uint32, NumRanges uint32, ClientSpecs []ClientSpec, Ranges []Range) []byte {
-	size := xgb.Pad(((20 + xgb.Pad((int(NumClientSpecs) * 4))) + xgb.Pad((int(NumRanges) * 24))))
+	size := xgb.Pad((((20 + xgb.Pad((int(NumClientSpecs) * 4))) + 4) + xgb.Pad((int(NumRanges) * 24))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -1067,7 +1070,7 @@ func registerClientsRequest(c *xgb.Conn, Context Context, ElementHeader ElementH
 	buf[b] = 2 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put32(buf[b:], uint32(Context))
@@ -1088,11 +1091,14 @@ func registerClientsRequest(c *xgb.Conn, Context Context, ElementHeader ElementH
 		xgb.Put32(buf[b:], uint32(ClientSpecs[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	b += RangeListBytes(buf[b:], Ranges)
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // UnregisterClientsCookie is a cookie used only for UnregisterClients requests.
@@ -1154,7 +1160,6 @@ func unregisterClientsRequest(c *xgb.Conn, Context Context, NumClientSpecs uint3
 		xgb.Put32(buf[b:], uint32(ClientSpecs[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
diff --git a/nexgb/render/render.go b/nexgb/render/render.go
index 80f4be7..f90065b 100644
--- a/nexgb/render/render.go
+++ b/nexgb/render/render.go
@@ -76,7 +76,7 @@ func (v Animcursorelt) Bytes() []byte {
 	xgb.Put32(buf[b:], v.Delay)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // AnimcursoreltListBytes writes a list of Animcursorelt values to a byte slice.
@@ -144,7 +144,7 @@ func (v Color) Bytes() []byte {
 	xgb.Put16(buf[b:], v.Alpha)
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // ColorListBytes writes a list of Color values to a byte slice.
@@ -256,7 +256,7 @@ func (v Directformat) Bytes() []byte {
 	xgb.Put16(buf[b:], v.AlphaMask)
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // DirectformatListBytes writes a list of Directformat values to a byte slice.
@@ -434,7 +434,7 @@ func (v Glyphinfo) Bytes() []byte {
 	xgb.Put16(buf[b:], uint16(v.YOff))
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // GlyphinfoListBytes writes a list of Glyphinfo values to a byte slice.
@@ -519,7 +519,7 @@ func (v Indexvalue) Bytes() []byte {
 	xgb.Put16(buf[b:], v.Alpha)
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // IndexvalueListBytes writes a list of Indexvalue values to a byte slice.
@@ -579,7 +579,7 @@ func (v Linefix) Bytes() []byte {
 		b += len(structBytes)
 	}
 
-	return buf
+	return buf[:b]
 }
 
 // LinefixListBytes writes a list of Linefix values to a byte slice.
@@ -802,7 +802,7 @@ func (v Pictdepth) Bytes() []byte {
 
 	b += PictvisualListBytes(buf[b:], v.Visuals)
 
-	return buf
+	return buf[:b]
 }
 
 // PictdepthListBytes writes a list of Pictdepth values to a byte slice.
@@ -904,7 +904,7 @@ func (v Pictforminfo) Bytes() []byte {
 	xgb.Put32(buf[b:], uint32(v.Colormap))
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // PictforminfoListBytes writes a list of Pictforminfo values to a byte slice.
@@ -964,7 +964,7 @@ func (v Pictscreen) Bytes() []byte {
 
 	b += PictdepthListBytes(buf[b:], v.Depths)
 
-	return buf
+	return buf[:b]
 }
 
 // PictscreenListBytes writes a list of Pictscreen values to a byte slice.
@@ -1087,7 +1087,7 @@ func (v Pictvisual) Bytes() []byte {
 	xgb.Put32(buf[b:], uint32(v.Format))
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // PictvisualListBytes writes a list of Pictvisual values to a byte slice.
@@ -1141,7 +1141,7 @@ func (v Pointfix) Bytes() []byte {
 	xgb.Put32(buf[b:], uint32(v.Y))
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // PointfixListBytes writes a list of Pointfix values to a byte slice.
@@ -1219,7 +1219,7 @@ func (v Spanfix) Bytes() []byte {
 	xgb.Put32(buf[b:], uint32(v.Y))
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // SpanfixListBytes writes a list of Spanfix values to a byte slice.
@@ -1331,7 +1331,7 @@ func (v Transform) Bytes() []byte {
 	xgb.Put32(buf[b:], uint32(v.Matrix33))
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // TransformListBytes writes a list of Transform values to a byte slice.
@@ -1391,7 +1391,7 @@ func (v Trap) Bytes() []byte {
 		b += len(structBytes)
 	}
 
-	return buf
+	return buf[:b]
 }
 
 // TrapListBytes writes a list of Trap values to a byte slice.
@@ -1465,7 +1465,7 @@ func (v Trapezoid) Bytes() []byte {
 		b += len(structBytes)
 	}
 
-	return buf
+	return buf[:b]
 }
 
 // TrapezoidListBytes writes a list of Trapezoid values to a byte slice.
@@ -1535,7 +1535,7 @@ func (v Triangle) Bytes() []byte {
 		b += len(structBytes)
 	}
 
-	return buf
+	return buf[:b]
 }
 
 // TriangleListBytes writes a list of Triangle values to a byte slice.
@@ -1610,7 +1610,7 @@ func (cook AddGlyphsCookie) Check() error {
 // Write request to wire for AddGlyphs
 // addGlyphsRequest writes a AddGlyphs request to a byte slice.
 func addGlyphsRequest(c *xgb.Conn, Glyphset Glyphset, GlyphsLen uint32, Glyphids []uint32, Glyphs []Glyphinfo, Data []byte) []byte {
-	size := xgb.Pad((((12 + xgb.Pad((int(GlyphsLen) * 4))) + xgb.Pad((int(GlyphsLen) * 12))) + xgb.Pad((len(Data) * 1))))
+	size := xgb.Pad(((((12 + xgb.Pad((int(GlyphsLen) * 4))) + 4) + xgb.Pad((int(GlyphsLen) * 12))) + xgb.Pad((len(Data) * 1))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -1620,7 +1620,7 @@ func addGlyphsRequest(c *xgb.Conn, Glyphset Glyphset, GlyphsLen uint32, Glyphids
 	buf[b] = 20 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put32(buf[b:], uint32(Glyphset))
@@ -1633,14 +1633,17 @@ func addGlyphsRequest(c *xgb.Conn, Glyphset Glyphset, GlyphsLen uint32, Glyphids
 		xgb.Put32(buf[b:], Glyphids[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	b += GlyphinfoListBytes(buf[b:], Glyphs)
 
 	copy(buf[b:], Data[:len(Data)])
-	b += xgb.Pad(int(len(Data)))
+	b += int(len(Data))
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // AddTrapsCookie is a cookie used only for AddTraps requests.
@@ -1932,7 +1935,7 @@ func compositeGlyphs16Request(c *xgb.Conn, Op byte, Src Picture, Dst Picture, Ma
 	b += 2
 
 	copy(buf[b:], Glyphcmds[:len(Glyphcmds)])
-	b += xgb.Pad(int(len(Glyphcmds)))
+	b += int(len(Glyphcmds))
 
 	return buf
 }
@@ -2010,7 +2013,7 @@ func compositeGlyphs32Request(c *xgb.Conn, Op byte, Src Picture, Dst Picture, Ma
 	b += 2
 
 	copy(buf[b:], Glyphcmds[:len(Glyphcmds)])
-	b += xgb.Pad(int(len(Glyphcmds)))
+	b += int(len(Glyphcmds))
 
 	return buf
 }
@@ -2088,7 +2091,7 @@ func compositeGlyphs8Request(c *xgb.Conn, Op byte, Src Picture, Dst Picture, Mas
 	b += 2
 
 	copy(buf[b:], Glyphcmds[:len(Glyphcmds)])
-	b += xgb.Pad(int(len(Glyphcmds)))
+	b += int(len(Glyphcmds))
 
 	return buf
 }
@@ -2186,7 +2189,7 @@ func (cook CreateConicalGradientCookie) Check() error {
 // Write request to wire for CreateConicalGradient
 // createConicalGradientRequest writes a CreateConicalGradient request to a byte slice.
 func createConicalGradientRequest(c *xgb.Conn, Picture Picture, Center Pointfix, Angle Fixed, NumStops uint32, Stops []Fixed, Colors []Color) []byte {
-	size := xgb.Pad(((24 + xgb.Pad((int(NumStops) * 4))) + xgb.Pad((int(NumStops) * 8))))
+	size := xgb.Pad((((24 + xgb.Pad((int(NumStops) * 4))) + 4) + xgb.Pad((int(NumStops) * 8))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -2196,7 +2199,7 @@ func createConicalGradientRequest(c *xgb.Conn, Picture Picture, Center Pointfix,
 	buf[b] = 36 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put32(buf[b:], uint32(Picture))
@@ -2218,11 +2221,14 @@ func createConicalGradientRequest(c *xgb.Conn, Picture Picture, Center Pointfix,
 		xgb.Put32(buf[b:], uint32(Stops[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	b += ColorListBytes(buf[b:], Colors)
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // CreateCursorCookie is a cookie used only for CreateCursor requests.
@@ -2383,7 +2389,7 @@ func (cook CreateLinearGradientCookie) Check() error {
 // Write request to wire for CreateLinearGradient
 // createLinearGradientRequest writes a CreateLinearGradient request to a byte slice.
 func createLinearGradientRequest(c *xgb.Conn, Picture Picture, P1 Pointfix, P2 Pointfix, NumStops uint32, Stops []Fixed, Colors []Color) []byte {
-	size := xgb.Pad(((28 + xgb.Pad((int(NumStops) * 4))) + xgb.Pad((int(NumStops) * 8))))
+	size := xgb.Pad((((28 + xgb.Pad((int(NumStops) * 4))) + 4) + xgb.Pad((int(NumStops) * 8))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -2393,7 +2399,7 @@ func createLinearGradientRequest(c *xgb.Conn, Picture Picture, P1 Pointfix, P2 P
 	buf[b] = 34 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put32(buf[b:], uint32(Picture))
@@ -2418,11 +2424,14 @@ func createLinearGradientRequest(c *xgb.Conn, Picture Picture, P1 Pointfix, P2 P
 		xgb.Put32(buf[b:], uint32(Stops[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	b += ColorListBytes(buf[b:], Colors)
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // CreatePictureCookie is a cookie used only for CreatePicture requests.
@@ -2530,7 +2539,7 @@ func (cook CreateRadialGradientCookie) Check() error {
 // Write request to wire for CreateRadialGradient
 // createRadialGradientRequest writes a CreateRadialGradient request to a byte slice.
 func createRadialGradientRequest(c *xgb.Conn, Picture Picture, Inner Pointfix, Outer Pointfix, InnerRadius Fixed, OuterRadius Fixed, NumStops uint32, Stops []Fixed, Colors []Color) []byte {
-	size := xgb.Pad(((36 + xgb.Pad((int(NumStops) * 4))) + xgb.Pad((int(NumStops) * 8))))
+	size := xgb.Pad((((36 + xgb.Pad((int(NumStops) * 4))) + 4) + xgb.Pad((int(NumStops) * 8))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -2540,7 +2549,7 @@ func createRadialGradientRequest(c *xgb.Conn, Picture Picture, Inner Pointfix, O
 	buf[b] = 35 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put32(buf[b:], uint32(Picture))
@@ -2571,11 +2580,14 @@ func createRadialGradientRequest(c *xgb.Conn, Picture Picture, Inner Pointfix, O
 		xgb.Put32(buf[b:], uint32(Stops[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	b += ColorListBytes(buf[b:], Colors)
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // CreateSolidFillCookie is a cookie used only for CreateSolidFill requests.
@@ -2818,7 +2830,6 @@ func freeGlyphsRequest(c *xgb.Conn, Glyphset Glyphset, Glyphs []Glyph) []byte {
 		xgb.Put32(buf[b:], uint32(Glyphs[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -2955,7 +2966,6 @@ func queryFiltersReply(buf []byte) *QueryFiltersReply {
 		v.Aliases[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	v.Filters = make([]xproto.Str, v.NumFilters)
 	b += xproto.StrReadList(buf[b:], v.Filters)
@@ -3023,9 +3033,11 @@ type QueryPictFormatsReply struct {
 	NumVisuals  uint32
 	NumSubpixel uint32
 	// padding: 4 bytes
-	Formats   []Pictforminfo // size: xgb.Pad((int(NumFormats) * 28))
-	Screens   []Pictscreen   // size: PictscreenListSize(Screens)
-	Subpixels []uint32       // size: xgb.Pad((int(NumSubpixel) * 4))
+	Formats []Pictforminfo // size: xgb.Pad((int(NumFormats) * 28))
+	// alignment gap to multiple of 4
+	Screens []Pictscreen // size: PictscreenListSize(Screens)
+	// alignment gap to multiple of 4
+	Subpixels []uint32 // size: xgb.Pad((int(NumSubpixel) * 4))
 }
 
 // Reply blocks and returns the reply data for a QueryPictFormats request.
@@ -3073,15 +3085,18 @@ func queryPictFormatsReply(buf []byte) *QueryPictFormatsReply {
 	v.Formats = make([]Pictforminfo, v.NumFormats)
 	b += PictforminfoReadList(buf[b:], v.Formats)
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.Screens = make([]Pictscreen, v.NumScreens)
 	b += PictscreenReadList(buf[b:], v.Screens)
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.Subpixels = make([]uint32, v.NumSubpixel)
 	for i := 0; i < int(v.NumSubpixel); i++ {
 		v.Subpixels[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -3455,7 +3470,7 @@ func (cook SetPictureFilterCookie) Check() error {
 // Write request to wire for SetPictureFilter
 // setPictureFilterRequest writes a SetPictureFilter request to a byte slice.
 func setPictureFilterRequest(c *xgb.Conn, Picture Picture, FilterLen uint16, Filter string, Values []Fixed) []byte {
-	size := xgb.Pad(((12 + xgb.Pad((int(FilterLen) * 1))) + xgb.Pad((len(Values) * 4))))
+	size := xgb.Pad((((12 + xgb.Pad((int(FilterLen) * 1))) + 4) + xgb.Pad((len(Values) * 4))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -3465,7 +3480,7 @@ func setPictureFilterRequest(c *xgb.Conn, Picture Picture, FilterLen uint16, Fil
 	buf[b] = 30 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put32(buf[b:], uint32(Picture))
@@ -3477,15 +3492,18 @@ func setPictureFilterRequest(c *xgb.Conn, Picture Picture, FilterLen uint16, Fil
 	b += 2 // padding
 
 	copy(buf[b:], Filter[:FilterLen])
-	b += xgb.Pad(int(FilterLen))
+	b += int(FilterLen)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	for i := 0; i < int(len(Values)); i++ {
 		xgb.Put32(buf[b:], uint32(Values[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // SetPictureTransformCookie is a cookie used only for SetPictureTransform requests.
diff --git a/nexgb/res/res.go b/nexgb/res/res.go
index 8311f95..dd53857 100644
--- a/nexgb/res/res.go
+++ b/nexgb/res/res.go
@@ -76,7 +76,7 @@ func (v Client) Bytes() []byte {
 	xgb.Put32(buf[b:], v.ResourceMask)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // ClientListBytes writes a list of Client values to a byte slice.
@@ -135,7 +135,7 @@ func (v ClientIdSpec) Bytes() []byte {
 	xgb.Put32(buf[b:], v.Mask)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // ClientIdSpecListBytes writes a list of ClientIdSpec values to a byte slice.
@@ -171,7 +171,6 @@ func ClientIdValueRead(buf []byte, v *ClientIdValue) int {
 		v.Value[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return b
 }
@@ -204,9 +203,8 @@ func (v ClientIdValue) Bytes() []byte {
 		xgb.Put32(buf[b:], v.Value[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
-	return buf
+	return buf[:b]
 }
 
 // ClientIdValueListBytes writes a list of ClientIdValue values to a byte slice.
@@ -269,7 +267,7 @@ func (v ResourceIdSpec) Bytes() []byte {
 	xgb.Put32(buf[b:], v.Type)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // ResourceIdSpecListBytes writes a list of ResourceIdSpec values to a byte slice.
@@ -340,7 +338,7 @@ func (v ResourceSizeSpec) Bytes() []byte {
 	xgb.Put32(buf[b:], v.UseCount)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // ResourceSizeSpecListBytes writes a list of ResourceSizeSpec values to a byte slice.
@@ -403,7 +401,7 @@ func (v ResourceSizeValue) Bytes() []byte {
 
 	b += ResourceSizeSpecListBytes(buf[b:], v.CrossReferences)
 
-	return buf
+	return buf[:b]
 }
 
 // ResourceSizeValueListBytes writes a list of ResourceSizeValue values to a byte slice.
@@ -466,7 +464,7 @@ func (v Type) Bytes() []byte {
 	xgb.Put32(buf[b:], v.Count)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // TypeListBytes writes a list of Type values to a byte slice.
diff --git a/nexgb/xcmisc/xcmisc.go b/nexgb/xcmisc/xcmisc.go
index 5cff5f1..2240ee1 100644
--- a/nexgb/xcmisc/xcmisc.go
+++ b/nexgb/xcmisc/xcmisc.go
@@ -228,7 +228,6 @@ func getXIDListReply(buf []byte) *GetXIDListReply {
 		v.Ids[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
diff --git a/nexgb/xevie/xevie.go b/nexgb/xevie/xevie.go
index f77d405..7e18f8d 100644
--- a/nexgb/xevie/xevie.go
+++ b/nexgb/xevie/xevie.go
@@ -72,7 +72,7 @@ func (v Event) Bytes() []byte {
 
 	b += 32 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // EventListBytes writes a list of Event values to a byte slice.
diff --git a/nexgb/xf86dri/xf86dri.go b/nexgb/xf86dri/xf86dri.go
index d88cc5d..6a07e41 100644
--- a/nexgb/xf86dri/xf86dri.go
+++ b/nexgb/xf86dri/xf86dri.go
@@ -90,7 +90,7 @@ func (v DrmClipRect) Bytes() []byte {
 	xgb.Put16(buf[b:], uint16(v.X3))
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // DrmClipRectListBytes writes a list of DrmClipRect values to a byte slice.
@@ -776,7 +776,6 @@ func getDeviceInfoReply(buf []byte) *GetDeviceInfoReply {
 		v.DevicePrivate[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -846,7 +845,8 @@ type GetDrawableInfoReply struct {
 	BackY              int16
 	NumBackClipRects   uint32
 	ClipRects          []DrmClipRect // size: xgb.Pad((int(NumClipRects) * 8))
-	BackClipRects      []DrmClipRect // size: xgb.Pad((int(NumBackClipRects) * 8))
+	// alignment gap to multiple of 4
+	BackClipRects []DrmClipRect // size: xgb.Pad((int(NumBackClipRects) * 8))
 }
 
 // Reply blocks and returns the reply data for a GetDrawableInfo request.
@@ -907,6 +907,8 @@ func getDrawableInfoReply(buf []byte) *GetDrawableInfoReply {
 	v.ClipRects = make([]DrmClipRect, v.NumClipRects)
 	b += DrmClipRectReadList(buf[b:], v.ClipRects)
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.BackClipRects = make([]DrmClipRect, v.NumBackClipRects)
 	b += DrmClipRectReadList(buf[b:], v.BackClipRects)
 
diff --git a/nexgb/xf86vidmode/xf86vidmode.go b/nexgb/xf86vidmode/xf86vidmode.go
index 8abb44e..5b0f1f8 100644
--- a/nexgb/xf86vidmode/xf86vidmode.go
+++ b/nexgb/xf86vidmode/xf86vidmode.go
@@ -408,7 +408,7 @@ func (v ModeInfo) Bytes() []byte {
 	xgb.Put32(buf[b:], v.Privsize)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // ModeInfoListBytes writes a list of ModeInfo values to a byte slice.
@@ -676,7 +676,7 @@ func addModeLineRequest(c *xgb.Conn, Screen uint32, Dotclock Dotclock, Hdisplay
 	b += 12 // padding
 
 	copy(buf[b:], Private[:Privsize])
-	b += xgb.Pad(int(Privsize))
+	b += int(Privsize)
 
 	return buf
 }
@@ -774,7 +774,7 @@ func deleteModeLineRequest(c *xgb.Conn, Screen uint32, Dotclock Dotclock, Hdispl
 	b += 4
 
 	copy(buf[b:], Private[:Privsize])
-	b += xgb.Pad(int(Privsize))
+	b += int(Privsize)
 
 	return buf
 }
@@ -956,7 +956,6 @@ func getDotClocksReply(buf []byte) *GetDotClocksReply {
 		v.Clock[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -1120,9 +1119,11 @@ type GetGammaRampReply struct {
 	// padding: 1 bytes
 	Size uint16
 	// padding: 22 bytes
-	Red   []uint16 // size: xgb.Pad((((int(Size) + 1) & -2) * 2))
+	Red []uint16 // size: xgb.Pad((((int(Size) + 1) & -2) * 2))
+	// alignment gap to multiple of 2
 	Green []uint16 // size: xgb.Pad((((int(Size) + 1) & -2) * 2))
-	Blue  []uint16 // size: xgb.Pad((((int(Size) + 1) & -2) * 2))
+	// alignment gap to multiple of 2
+	Blue []uint16 // size: xgb.Pad((((int(Size) + 1) & -2) * 2))
 }
 
 // Reply blocks and returns the reply data for a GetGammaRamp request.
@@ -1160,21 +1161,22 @@ func getGammaRampReply(buf []byte) *GetGammaRampReply {
 		v.Red[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 1) & ^1 // alignment gap
 
 	v.Green = make([]uint16, ((int(v.Size) + 1) & -2))
 	for i := 0; i < int(((int(v.Size) + 1) & -2)); i++ {
 		v.Green[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 1) & ^1 // alignment gap
 
 	v.Blue = make([]uint16, ((int(v.Size) + 1) & -2))
 	for i := 0; i < int(((int(v.Size) + 1) & -2)); i++ {
 		v.Blue[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -1413,7 +1415,7 @@ func getModeLineReply(buf []byte) *GetModeLineReply {
 
 	v.Private = make([]byte, v.Privsize)
 	copy(v.Private[:v.Privsize], buf[b:])
-	b += xgb.Pad(int(v.Privsize))
+	b += int(v.Privsize)
 
 	return v
 }
@@ -1479,7 +1481,8 @@ type GetMonitorReply struct {
 	NumHsync     byte
 	NumVsync     byte
 	// padding: 20 bytes
-	Hsync        []Syncrange // size: xgb.Pad((int(NumHsync) * 4))
+	Hsync []Syncrange // size: xgb.Pad((int(NumHsync) * 4))
+	// alignment gap to multiple of 4
 	Vsync        []Syncrange // size: xgb.Pad((int(NumVsync) * 4))
 	Vendor       string      // size: xgb.Pad((int(VendorLength) * 1))
 	AlignmentPad []byte      // size: xgb.Pad(((((int(VendorLength) + 3) & -4) - int(VendorLength)) * 1))
@@ -1530,14 +1533,14 @@ func getMonitorReply(buf []byte) *GetMonitorReply {
 		v.Hsync[i] = Syncrange(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Vsync = make([]Syncrange, v.NumVsync)
 	for i := 0; i < int(v.NumVsync); i++ {
 		v.Vsync[i] = Syncrange(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	{
 		byteString := make([]byte, v.VendorLength)
@@ -1548,7 +1551,7 @@ func getMonitorReply(buf []byte) *GetMonitorReply {
 
 	v.AlignmentPad = make([]byte, (((int(v.VendorLength) + 3) & -4) - int(v.VendorLength)))
 	copy(v.AlignmentPad[:(((int(v.VendorLength)+3)&-4)-int(v.VendorLength))], buf[b:])
-	b += xgb.Pad(int((((int(v.VendorLength) + 3) & -4) - int(v.VendorLength))))
+	b += int((((int(v.VendorLength) + 3) & -4) - int(v.VendorLength)))
 
 	{
 		byteString := make([]byte, v.ModelLength)
@@ -1922,7 +1925,7 @@ func modModeLineRequest(c *xgb.Conn, Screen uint32, Hdisplay uint16, Hsyncstart
 	b += 4
 
 	copy(buf[b:], Private[:Privsize])
-	b += xgb.Pad(int(Privsize))
+	b += int(Privsize)
 
 	return buf
 }
@@ -2178,7 +2181,7 @@ func (cook SetGammaRampCookie) Check() error {
 // Write request to wire for SetGammaRamp
 // setGammaRampRequest writes a SetGammaRamp request to a byte slice.
 func setGammaRampRequest(c *xgb.Conn, Screen uint16, Size uint16, Red []uint16, Green []uint16, Blue []uint16) []byte {
-	size := xgb.Pad((((8 + xgb.Pad((((int(Size) + 1) & -2) * 2))) + xgb.Pad((((int(Size) + 1) & -2) * 2))) + xgb.Pad((((int(Size) + 1) & -2) * 2))))
+	size := xgb.Pad((((((8 + xgb.Pad((((int(Size) + 1) & -2) * 2))) + 2) + xgb.Pad((((int(Size) + 1) & -2) * 2))) + 2) + xgb.Pad((((int(Size) + 1) & -2) * 2))))
 	b := 0
 	buf := make([]byte, size)
 
@@ -2188,7 +2191,7 @@ func setGammaRampRequest(c *xgb.Conn, Screen uint16, Size uint16, Red []uint16,
 	buf[b] = 18 // request opcode
 	b += 1
 
-	xgb.Put16(buf[b:], uint16(size/4)) // write request size in 4-byte units
+	blen := b
 	b += 2
 
 	xgb.Put16(buf[b:], Screen)
@@ -2201,21 +2204,24 @@ func setGammaRampRequest(c *xgb.Conn, Screen uint16, Size uint16, Red []uint16,
 		xgb.Put16(buf[b:], Red[i])
 		b += 2
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 1) & ^1 // alignment gap
 
 	for i := 0; i < int(((int(Size) + 1) & -2)); i++ {
 		xgb.Put16(buf[b:], Green[i])
 		b += 2
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 1) & ^1 // alignment gap
 
 	for i := 0; i < int(((int(Size) + 1) & -2)); i++ {
 		xgb.Put16(buf[b:], Blue[i])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
-	return buf
+	b = xgb.Pad(b)
+	xgb.Put16(buf[blen:], uint16(b/4)) // write request size in 4-byte units
+	return buf[:b]
 }
 
 // SetViewPortCookie is a cookie used only for SetViewPort requests.
@@ -2432,7 +2438,7 @@ func switchToModeRequest(c *xgb.Conn, Screen uint32, Dotclock Dotclock, Hdisplay
 	b += 4
 
 	copy(buf[b:], Private[:Privsize])
-	b += xgb.Pad(int(Privsize))
+	b += int(Privsize)
 
 	return buf
 }
@@ -2566,7 +2572,7 @@ func validateModeLineRequest(c *xgb.Conn, Screen uint32, Dotclock Dotclock, Hdis
 	b += 4
 
 	copy(buf[b:], Private[:Privsize])
-	b += xgb.Pad(int(Privsize))
+	b += int(Privsize)
 
 	return buf
 }
diff --git a/nexgb/xfixes/xfixes.go b/nexgb/xfixes/xfixes.go
index 9a08c93..ef08c9a 100644
--- a/nexgb/xfixes/xfixes.go
+++ b/nexgb/xfixes/xfixes.go
@@ -489,7 +489,7 @@ func changeCursorByNameRequest(c *xgb.Conn, Src xproto.Cursor, Nbytes uint16, Na
 	b += 2 // padding
 
 	copy(buf[b:], Name[:Nbytes])
-	b += xgb.Pad(int(Nbytes))
+	b += int(Nbytes)
 
 	return buf
 }
@@ -697,7 +697,6 @@ func createPointerBarrierRequest(c *xgb.Conn, Barrier Barrier, Window xproto.Win
 		xgb.Put16(buf[b:], Devices[i])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1367,7 +1366,6 @@ func getCursorImageReply(buf []byte) *GetCursorImageReply {
 		v.CursorImage[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -1433,7 +1431,8 @@ type GetCursorImageAndNameReply struct {
 	CursorAtom   xproto.Atom
 	Nbytes       uint16
 	// padding: 2 bytes
-	Name        string   // size: xgb.Pad((int(Nbytes) * 1))
+	Name string // size: xgb.Pad((int(Nbytes) * 1))
+	// alignment gap to multiple of 4
 	CursorImage []uint32 // size: xgb.Pad(((int(Width) * int(Height)) * 4))
 }
 
@@ -1498,12 +1497,13 @@ func getCursorImageAndNameReply(buf []byte) *GetCursorImageAndNameReply {
 		b += int(v.Nbytes)
 	}
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.CursorImage = make([]uint32, (int(v.Width) * int(v.Height)))
 	for i := 0; i < int((int(v.Width) * int(v.Height))); i++ {
 		v.CursorImage[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -2143,7 +2143,7 @@ func setCursorNameRequest(c *xgb.Conn, Cursor xproto.Cursor, Nbytes uint16, Name
 	b += 2 // padding
 
 	copy(buf[b:], Name[:Nbytes])
-	b += xgb.Pad(int(Nbytes))
+	b += int(Nbytes)
 
 	return buf
 }
diff --git a/nexgb/xgbgen/aligngap.go b/nexgb/xgbgen/aligngap.go
new file mode 100644
index 0000000..1e07e18
--- /dev/null
+++ b/nexgb/xgbgen/aligngap.go
@@ -0,0 +1,130 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func (p *Protocol) AddAlignGaps() {
+	for i := range p.Imports {
+		p.Imports[i].AddAlignGaps()
+	}
+	for i := range p.Types {
+		switch t := p.Types[i].(type) {
+		case *Struct:
+			t.Fields = addAlignGapsToFields(t.xmlName, t.Fields)
+		case *Event:
+			t.Fields = addAlignGapsToFields(t.xmlName, t.Fields)
+		case *Error:
+			t.Fields = addAlignGapsToFields(t.xmlName, t.Fields)
+		}
+	}
+	for i := range p.Requests {
+		p.Requests[i].Fields = addAlignGapsToFields(p.Requests[i].xmlName, p.Requests[i].Fields)
+		if p.Requests[i].Reply != nil {
+			p.Requests[i].Reply.Fields = addAlignGapsToFields(p.Requests[i].xmlName, p.Requests[i].Reply.Fields)
+		}
+	}
+}
+
+func addAlignGapsToFields(name string, fields []Field) []Field {
+	var i int
+	for i = 0; i < len(fields); i++ {
+		if _, ok := fields[i].(*ListField); ok {
+			break
+		}
+	}
+	if i >= len(fields) {
+		return fields
+	}
+
+	r := make([]Field, 0, len(fields)+2)
+	r = append(r, fields[:i]...)
+
+	r = append(r, fields[i])
+	for i = i + 1; i < len(fields); i++ {
+		switch f := fields[i].(type) {
+		case *ListField:
+			// ok, add padding
+			sz := xcbSizeOfType(f.Type)
+			switch {
+			case sz == 1:
+				// nothing
+			case sz == 2:
+				r = append(r, &PadField{0, 2})
+			case sz == 3:
+				panic(fmt.Errorf("Alignment is not a power of 2"))
+			case sz >= 4:
+				r = append(r, &PadField{0, 4})
+			}
+
+		case *LocalField:
+			// nothing
+
+		default:
+			fmt.Fprintf(os.Stderr, "Can't add alignment gaps, mix of list and non-list fields: %s\n", name)
+			return fields
+		}
+		r = append(r, fields[i])
+	}
+
+	return r
+}
+
+func xcbSizeOfField(fld Field) int {
+	switch f := fld.(type) {
+	case *PadField:
+		return int(f.Bytes)
+
+	case *SingleField:
+		return xcbSizeOfType(f.Type)
+
+	case *ListField:
+		return 0
+
+	case *ExprField:
+		return xcbSizeOfType(f.Type)
+
+	case *ValueField:
+		return xcbSizeOfType(f.MaskType)
+
+	case *SwitchField:
+		return 0
+
+	default:
+		return 0
+	}
+}
+
+func xcbSizeOfType(typ Type) int {
+	switch t := typ.(type) {
+	case *Resource:
+		return 4
+
+	case *TypeDef:
+		return t.Size().Eval()
+
+	case *Base:
+		return t.Size().Eval()
+
+	case *Struct:
+		sz := 0
+		for i := range t.Fields {
+			sz += xcbSizeOfField(t.Fields[i])
+		}
+		return sz
+
+	case *Union:
+		sz := 0
+		for i := range t.Fields {
+			csz := xcbSizeOfField(t.Fields[i])
+			if csz > sz {
+				sz = csz
+			}
+		}
+		return sz
+
+	default:
+		return 0
+	}
+}
diff --git a/nexgb/xgbgen/context.go b/nexgb/xgbgen/context.go
index af0f598..f64f339 100644
--- a/nexgb/xgbgen/context.go
+++ b/nexgb/xgbgen/context.go
@@ -50,6 +50,8 @@ func (c *Context) Morph(xmlBytes []byte) {
 	// Translate XML types to nice types
 	c.protocol = parsedXml.Translate(nil)
 
+	c.protocol.AddAlignGaps()
+
 	// Start with Go header.
 	c.Putln("// Package %s is the X client API for the %s extension.",
 		c.protocol.PkgName(), c.protocol.ExtXName)
diff --git a/nexgb/xgbgen/field.go b/nexgb/xgbgen/field.go
index 16760d4..bf3b3be 100644
--- a/nexgb/xgbgen/field.go
+++ b/nexgb/xgbgen/field.go
@@ -50,6 +50,7 @@ func (pad *PadField) Initialize(p *Protocol) {}
 // It is also used in size calculation.
 type PadField struct {
 	Bytes uint
+	Align uint16
 }
 
 func (p *PadField) SrcName() string {
@@ -65,7 +66,11 @@ func (f *PadField) SrcType() string {
 }
 
 func (p *PadField) Size() Size {
-	return newFixedSize(p.Bytes)
+	if p.Align > 0 {
+		return newFixedSize(uint(p.Align), false)
+	} else {
+		return newFixedSize(p.Bytes, true)
+	}
 }
 
 // SingleField represents most of the fields in an XML protocol description.
@@ -130,9 +135,9 @@ func (f *ListField) Length() Size {
 			Expr: &FieldRef{
 				Name: f.SrcName(),
 			},
-		})
+		}, true)
 	}
-	return newExpressionSize(f.LengthExpr)
+	return newExpressionSize(f.LengthExpr, true)
 }
 
 // Size computes the *size* of a list (in bytes).
@@ -142,8 +147,9 @@ func (f *ListField) Length() Size {
 // special function written in go_struct.go to compute the size (since the
 // size in this case can only be computed recursively).
 func (f *ListField) Size() Size {
+	elsz := f.Type.Size()
 	simpleLen := &Padding{
-		Expr: newBinaryOp("*", f.Length().Expression, f.Type.Size().Expression),
+		Expr: newBinaryOp("*", f.Length().Expression, elsz.Expression),
 	}
 
 	switch field := f.Type.(type) {
@@ -153,18 +159,18 @@ func (f *ListField) Size() Size {
 				Name: fmt.Sprintf("%sListSize", f.Type.SrcName()),
 				Expr: &FieldRef{Name: f.SrcName()},
 			}
-			return newExpressionSize(sizeFun)
+			return newExpressionSize(sizeFun, elsz.exact)
 		} else {
-			return newExpressionSize(simpleLen)
+			return newExpressionSize(simpleLen, elsz.exact)
 		}
 	case *Union:
-		return newExpressionSize(simpleLen)
+		return newExpressionSize(simpleLen, elsz.exact)
 	case *Base:
-		return newExpressionSize(simpleLen)
+		return newExpressionSize(simpleLen, elsz.exact)
 	case *Resource:
-		return newExpressionSize(simpleLen)
+		return newExpressionSize(simpleLen, elsz.exact)
 	case *TypeDef:
-		return newExpressionSize(simpleLen)
+		return newExpressionSize(simpleLen, elsz.exact)
 	default:
 		log.Panicf("Cannot compute list size with type '%T'.", f.Type)
 	}
@@ -258,7 +264,7 @@ func (f *ValueField) Size() Size {
 				},
 			},
 		},
-	})
+	}, true)
 	return maskSize.Add(listSize)
 }
 
@@ -270,7 +276,7 @@ func (f *ValueField) ListLength() Size {
 				Name: f.MaskName,
 			},
 		},
-	})
+	}, true)
 }
 
 func (f *ValueField) Initialize(p *Protocol) {
@@ -303,7 +309,7 @@ func (f *SwitchField) SrcType() string {
 // expression that finds *which* bitcase fields are included, and sums the
 // sizes of those fields.
 func (f *SwitchField) Size() Size {
-	return newFixedSize(0)
+	return newFixedSize(0, true)
 }
 
 func (f *SwitchField) Initialize(p *Protocol) {
diff --git a/nexgb/xgbgen/go.go b/nexgb/xgbgen/go.go
index 6c680e8..ace4e00 100644
--- a/nexgb/xgbgen/go.go
+++ b/nexgb/xgbgen/go.go
@@ -103,15 +103,27 @@ func (td *TypeDef) Define(c *Context) {
 
 // Pad fields
 func (f *PadField) Define(c *Context) {
-	c.Putln("// padding: %d bytes", f.Bytes)
+	if f.Align > 0 {
+		c.Putln("// alignment gap to multiple of %d", f.Align)
+	} else {
+		c.Putln("// padding: %d bytes", f.Bytes)
+	}
 }
 
 func (f *PadField) Read(c *Context, prefix string) {
-	c.Putln("b += %s // padding", f.Size())
+	if f.Align > 0 {
+		c.Putln("b = (b + %d) & ^%d // alignment gap", f.Align-1, f.Align-1)
+	} else {
+		c.Putln("b += %s // padding", f.Size())
+	}
 }
 
 func (f *PadField) Write(c *Context, prefix string) {
-	c.Putln("b += %s // padding", f.Size())
+	if f.Align > 0 {
+		c.Putln("b = (b + %d) & ^%d // alignment gap", f.Align-1, f.Align-1)
+	} else {
+		c.Putln("b += %s // padding", f.Size())
+	}
 }
 
 // Local fields
diff --git a/nexgb/xgbgen/go_list.go b/nexgb/xgbgen/go_list.go
index fa8df69..1e85d9f 100644
--- a/nexgb/xgbgen/go_list.go
+++ b/nexgb/xgbgen/go_list.go
@@ -21,7 +21,6 @@ func (f *ListField) Read(c *Context, prefix string) {
 		c.Putln("for i := 0; i < int(%s); i++ {", length)
 		ReadSimpleSingleField(c, fmt.Sprintf("%s%s[i]", prefix, f.SrcName()), t)
 		c.Putln("}")
-		c.Putln("b = xgb.Pad(b)")
 	case *Base:
 		length := f.LengthExpr.Reduce(prefix)
 		if strings.ToLower(t.XmlName()) == "char" {
@@ -38,7 +37,7 @@ func (f *ListField) Read(c *Context, prefix string) {
 			c.Putln("%s%s = make([]%s, %s)",
 				prefix, f.SrcName(), t.SrcName(), length)
 			c.Putln("copy(%s%s[:%s], buf[b:])", prefix, f.SrcName(), length)
-			c.Putln("b += xgb.Pad(int(%s))", length)
+			c.Putln("b += int(%s)", length)
 		} else {
 			c.Putln("%s%s = make([]%s, %s)",
 				prefix, f.SrcName(), t.SrcName(), length)
@@ -46,7 +45,6 @@ func (f *ListField) Read(c *Context, prefix string) {
 			ReadSimpleSingleField(c,
 				fmt.Sprintf("%s%s[i]", prefix, f.SrcName()), t)
 			c.Putln("}")
-			c.Putln("b = xgb.Pad(b)")
 		}
 	case *TypeDef:
 		length := f.LengthExpr.Reduce(prefix)
@@ -55,7 +53,6 @@ func (f *ListField) Read(c *Context, prefix string) {
 		c.Putln("for i := 0; i < int(%s); i++ {", length)
 		ReadSimpleSingleField(c, fmt.Sprintf("%s%s[i]", prefix, f.SrcName()), t)
 		c.Putln("}")
-		c.Putln("b = xgb.Pad(b)")
 	case *Union:
 		c.Putln("%s%s = make([]%s, %s)",
 			prefix, f.SrcName(), t.SrcName(), f.LengthExpr.Reduce(prefix))
@@ -80,18 +77,16 @@ func (f *ListField) Write(c *Context, prefix string) {
 		WriteSimpleSingleField(c,
 			fmt.Sprintf("%s%s[i]", prefix, f.SrcName()), t)
 		c.Putln("}")
-		c.Putln("b = xgb.Pad(b)")
 	case *Base:
 		length := f.Length().Reduce(prefix)
 		if t.SrcName() == "byte" {
 			c.Putln("copy(buf[b:], %s%s[:%s])", prefix, f.SrcName(), length)
-			c.Putln("b += xgb.Pad(int(%s))", length)
+			c.Putln("b += int(%s)", length)
 		} else {
 			c.Putln("for i := 0; i < int(%s); i++ {", length)
 			WriteSimpleSingleField(c,
 				fmt.Sprintf("%s%s[i]", prefix, f.SrcName()), t)
 			c.Putln("}")
-			c.Putln("b = xgb.Pad(b)")
 		}
 	case *TypeDef:
 		length := f.Length().Reduce(prefix)
@@ -99,7 +94,6 @@ func (f *ListField) Write(c *Context, prefix string) {
 		WriteSimpleSingleField(c,
 			fmt.Sprintf("%s%s[i]", prefix, f.SrcName()), t)
 		c.Putln("}")
-		c.Putln("b = xgb.Pad(b)")
 	case *Union:
 		c.Putln("b += %sListBytes(buf[b:], %s%s)",
 			t.SrcName(), prefix, f.SrcName())
diff --git a/nexgb/xgbgen/go_request_reply.go b/nexgb/xgbgen/go_request_reply.go
index a2c6d9c..d82e157 100644
--- a/nexgb/xgbgen/go_request_reply.go
+++ b/nexgb/xgbgen/go_request_reply.go
@@ -138,18 +138,32 @@ func (r *Request) ReadReply(c *Context) {
 }
 
 func (r *Request) WriteRequest(c *Context) {
-	writeSize := func() {
-		c.Putln("xgb.Put16(buf[b:], uint16(size / 4)) " +
-			"// write request size in 4-byte units")
+	sz := r.Size(c)
+	writeSize1 := func() {
+		if sz.exact {
+			c.Putln("xgb.Put16(buf[b:], uint16(size / 4)) " +
+				"// write request size in 4-byte units")
+		} else {
+			c.Putln("blen := b")
+		}
 		c.Putln("b += 2")
 		c.Putln("")
 	}
+	writeSize2 := func() {
+		if sz.exact {
+			c.Putln("return buf")
+			return
+		}
+		c.Putln("b = xgb.Pad(b)")
+		c.Putln("xgb.Put16(buf[blen:], uint16(b / 4)) // write request size in 4-byte units")
+		c.Putln("return buf[:b]")
+	}
 	c.Putln("// Write request to wire for %s", r.SrcName())
 	c.Putln("// %s writes a %s request to a byte slice.",
 		r.ReqName(), r.SrcName())
 	c.Putln("func %s(c *xgb.Conn, %s) []byte {",
 		r.ReqName(), r.ParamNameTypes())
-	c.Putln("size := %s", r.Size(c))
+	c.Putln("size := %s", sz)
 	c.Putln("b := 0")
 	c.Putln("buf := make([]byte, size)")
 	c.Putln("")
@@ -165,18 +179,18 @@ func (r *Request) WriteRequest(c *Context) {
 		if !c.protocol.isExt() {
 			c.Putln("b += 1 // padding")
 		}
-		writeSize()
+		writeSize1()
 	} else if c.protocol.isExt() {
-		writeSize()
+		writeSize1()
 	}
 	for i, field := range r.Fields {
 		field.Write(c, "")
 		c.Putln("")
 		if i == 0 && !c.protocol.isExt() {
-			writeSize()
+			writeSize1()
 		}
 	}
-	c.Putln("return buf")
+	writeSize2()
 	c.Putln("}")
 	c.Putln("")
 }
diff --git a/nexgb/xgbgen/go_struct.go b/nexgb/xgbgen/go_struct.go
index 0f18084..ee74d90 100644
--- a/nexgb/xgbgen/go_struct.go
+++ b/nexgb/xgbgen/go_struct.go
@@ -78,7 +78,7 @@ func (s *Struct) Write(c *Context) {
 		field.Write(c, "v.")
 		c.Putln("")
 	}
-	c.Putln("return buf")
+	c.Putln("return buf[:b]")
 	c.Putln("}")
 	c.Putln("")
 }
diff --git a/nexgb/xgbgen/request_reply.go b/nexgb/xgbgen/request_reply.go
index 11a4e44..ae4eccb 100644
--- a/nexgb/xgbgen/request_reply.go
+++ b/nexgb/xgbgen/request_reply.go
@@ -91,7 +91,7 @@ func (r *Request) CookieName() string {
 // If it's a core protocol request, then we only account for *three*
 // bytes of the header (remove the extension opcode).
 func (r *Request) Size(c *Context) Size {
-	size := newFixedSize(0)
+	size := newFixedSize(0, true)
 
 	// If this is a core protocol request, we squeeze in an extra byte of
 	// data (from the fields below) between the opcode and the size of the
@@ -99,9 +99,9 @@ func (r *Request) Size(c *Context) Size {
 	// by the opcode of the request (while the first byte is always occupied
 	// by the opcode of the extension).
 	if !c.protocol.isExt() {
-		size = size.Add(newFixedSize(3))
+		size = size.Add(newFixedSize(3, true))
 	} else {
-		size = size.Add(newFixedSize(4))
+		size = size.Add(newFixedSize(4, true))
 	}
 
 	for _, field := range r.Fields {
@@ -122,7 +122,7 @@ func (r *Request) Size(c *Context) Size {
 	}
 	return newExpressionSize(&Padding{
 		Expr: size.Expression,
-	})
+	}, size.exact)
 }
 
 // Reply encapsulates the fields associated with a 'reply' element.
@@ -136,10 +136,10 @@ type Reply struct {
 // 2 bytes: A sequence number
 // 4 bytes: Number of additional bytes in 4-byte units past initial 32 bytes.
 func (r *Reply) Size() Size {
-	size := newFixedSize(0)
+	size := newFixedSize(0, true)
 
 	// Account for reply discriminant, sequence number and reply length
-	size = size.Add(newFixedSize(7))
+	size = size.Add(newFixedSize(7, true))
 
 	for _, field := range r.Fields {
 		size = size.Add(field.Size())
diff --git a/nexgb/xgbgen/size.go b/nexgb/xgbgen/size.go
index 8836892..6e49371 100644
--- a/nexgb/xgbgen/size.go
+++ b/nexgb/xgbgen/size.go
@@ -7,24 +7,25 @@ package main
 // for adding and multiplying sizes.
 type Size struct {
 	Expression
+	exact bool
 }
 
 // newFixedSize creates a new Size with some fixed and known value.
-func newFixedSize(fixed uint) Size {
-	return Size{&Value{v: int(fixed)}}
+func newFixedSize(fixed uint, exact bool) Size {
+	return Size{&Value{v: int(fixed)}, exact}
 }
 
 // newExpressionSize creates a new Size with some expression.
-func newExpressionSize(variable Expression) Size {
-	return Size{variable}
+func newExpressionSize(variable Expression, exact bool) Size {
+	return Size{variable, exact}
 }
 
 // Add adds s1 and s2 and returns a new Size.
 func (s1 Size) Add(s2 Size) Size {
-	return Size{newBinaryOp("+", s1, s2)}
+	return Size{newBinaryOp("+", s1, s2), s1.exact && s2.exact}
 }
 
 // Multiply mupltiplies s1 and s2 and returns a new Size.
 func (s1 Size) Multiply(s2 Size) Size {
-	return Size{newBinaryOp("*", s1, s2)}
+	return Size{newBinaryOp("*", s1, s2), s1.exact && s2.exact}
 }
diff --git a/nexgb/xgbgen/translation.go b/nexgb/xgbgen/translation.go
index b7e67e2..f595e5f 100644
--- a/nexgb/xgbgen/translation.go
+++ b/nexgb/xgbgen/translation.go
@@ -43,7 +43,7 @@ func (xml *XML) Translate(parent *Protocol) *Protocol {
 		newBaseType := &Base{
 			srcName: srcName,
 			xmlName: xmlName,
-			size:    newFixedSize(BaseTypeSizes[xmlName]),
+			size:    newFixedSize(BaseTypeSizes[xmlName], true),
 		}
 		protocol.Types = append(protocol.Types, newBaseType)
 	}
diff --git a/nexgb/xgbgen/type.go b/nexgb/xgbgen/type.go
index ded5be2..59f1a2d 100644
--- a/nexgb/xgbgen/type.go
+++ b/nexgb/xgbgen/type.go
@@ -154,7 +154,7 @@ func (r *Resource) XmlName() string {
 }
 
 func (r *Resource) Size() Size {
-	return newFixedSize(BaseTypeSizes["Id"])
+	return newFixedSize(BaseTypeSizes["Id"], true)
 }
 
 func (r *Resource) Initialize(p *Protocol) {
@@ -201,7 +201,7 @@ func (e *Event) XmlName() string {
 }
 
 func (e *Event) Size() Size {
-	return newExpressionSize(&Value{v: 32})
+	return newExpressionSize(&Value{v: 32}, true)
 }
 
 func (e *Event) Initialize(p *Protocol) {
@@ -231,7 +231,7 @@ func (e *EventCopy) XmlName() string {
 }
 
 func (e *EventCopy) Size() Size {
-	return newExpressionSize(&Value{v: 32})
+	return newExpressionSize(&Value{v: 32}, true)
 }
 
 func (e *EventCopy) Initialize(p *Protocol) {
@@ -262,7 +262,7 @@ func (e *Error) XmlName() string {
 }
 
 func (e *Error) Size() Size {
-	return newExpressionSize(&Value{v: 32})
+	return newExpressionSize(&Value{v: 32}, true)
 }
 
 func (e *Error) Initialize(p *Protocol) {
@@ -296,7 +296,7 @@ func (e *ErrorCopy) XmlName() string {
 }
 
 func (e *ErrorCopy) Size() Size {
-	return newExpressionSize(&Value{v: 32})
+	return newExpressionSize(&Value{v: 32}, true)
 }
 
 func (e *ErrorCopy) Initialize(p *Protocol) {
@@ -330,7 +330,7 @@ func (s *Struct) XmlName() string {
 }
 
 func (s *Struct) Size() Size {
-	size := newFixedSize(0)
+	size := newFixedSize(0, true)
 	for _, field := range s.Fields {
 		size = size.Add(field.Size())
 	}
diff --git a/nexgb/xinerama/xinerama.go b/nexgb/xinerama/xinerama.go
index 28410c6..75c773c 100644
--- a/nexgb/xinerama/xinerama.go
+++ b/nexgb/xinerama/xinerama.go
@@ -90,7 +90,7 @@ func (v ScreenInfo) Bytes() []byte {
 	xgb.Put16(buf[b:], v.Height)
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // ScreenInfoListBytes writes a list of ScreenInfo values to a byte slice.
diff --git a/nexgb/xprint/xprint.go b/nexgb/xprint/xprint.go
index 7a7279f..5ed49a0 100644
--- a/nexgb/xprint/xprint.go
+++ b/nexgb/xprint/xprint.go
@@ -336,7 +336,6 @@ func PrinterRead(buf []byte, v *Printer) int {
 		v.Name[i] = String8(buf[b])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	v.DescLen = xgb.Get32(buf[b:])
 	b += 4
@@ -346,7 +345,6 @@ func PrinterRead(buf []byte, v *Printer) int {
 		v.Description[i] = String8(buf[b])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return b
 }
@@ -373,7 +371,6 @@ func (v Printer) Bytes() []byte {
 		buf[b] = byte(v.Name[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	xgb.Put32(buf[b:], v.DescLen)
 	b += 4
@@ -382,9 +379,8 @@ func (v Printer) Bytes() []byte {
 		buf[b] = byte(v.Description[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
-	return buf
+	return buf[:b]
 }
 
 // PrinterListBytes writes a list of Printer values to a byte slice.
@@ -496,13 +492,11 @@ func createContextRequest(c *xgb.Conn, ContextId uint32, PrinterNameLen uint32,
 		buf[b] = byte(PrinterName[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	for i := 0; i < int(LocaleLen); i++ {
 		buf[b] = byte(Locale[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1003,7 +997,7 @@ func printGetDocumentDataReply(buf []byte) *PrintGetDocumentDataReply {
 
 	v.Data = make([]byte, v.DataLen)
 	copy(v.Data[:v.DataLen], buf[b:])
-	b += xgb.Pad(int(v.DataLen))
+	b += int(v.DataLen)
 
 	return v
 }
@@ -1193,7 +1187,6 @@ func printGetOneAttributesReply(buf []byte) *PrintGetOneAttributesReply {
 		v.Value[i] = String8(buf[b])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -1229,7 +1222,6 @@ func printGetOneAttributesRequest(c *xgb.Conn, Context Pcontext, NameLen uint32,
 		buf[b] = byte(Name[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1441,13 +1433,11 @@ func printGetPrinterListRequest(c *xgb.Conn, PrinterNameLen uint32, LocaleLen ui
 		buf[b] = byte(PrinterName[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	for i := 0; i < int(LocaleLen); i++ {
 		buf[b] = byte(Locale[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1707,19 +1697,17 @@ func printPutDocumentDataRequest(c *xgb.Conn, Drawable xproto.Drawable, LenData
 	b += 2
 
 	copy(buf[b:], Data[:LenData])
-	b += xgb.Pad(int(LenData))
+	b += int(LenData)
 
 	for i := 0; i < int(len(DocFormat)); i++ {
 		buf[b] = byte(DocFormat[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	for i := 0; i < int(len(Options)); i++ {
 		buf[b] = byte(Options[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -1796,7 +1784,6 @@ func printQueryScreensReply(buf []byte) *PrintQueryScreensReply {
 		v.Roots[i] = xproto.Window(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -2091,7 +2078,6 @@ func printSetAttributesRequest(c *xgb.Conn, Context Pcontext, StringLen uint32,
 		buf[b] = byte(Attributes[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
diff --git a/nexgb/xproto/xproto.go b/nexgb/xproto/xproto.go
index 36ab545..728f85f 100644
--- a/nexgb/xproto/xproto.go
+++ b/nexgb/xproto/xproto.go
@@ -179,7 +179,7 @@ func (v Arc) Bytes() []byte {
 	xgb.Put16(buf[b:], uint16(v.Angle2))
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // ArcListBytes writes a list of Arc values to a byte slice.
@@ -603,7 +603,7 @@ func (v Char2b) Bytes() []byte {
 	buf[b] = v.Byte2
 	b += 1
 
-	return buf
+	return buf[:b]
 }
 
 // Char2bListBytes writes a list of Char2b values to a byte slice.
@@ -685,7 +685,7 @@ func (v Charinfo) Bytes() []byte {
 	xgb.Put16(buf[b:], v.Attributes)
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // CharinfoListBytes writes a list of Charinfo values to a byte slice.
@@ -932,7 +932,7 @@ func ClientMessageDataUnionData8New(Data8 []byte) ClientMessageDataUnion {
 	buf := make([]byte, 20)
 
 	copy(buf[b:], Data8[:20])
-	b += xgb.Pad(int(20))
+	b += int(20)
 
 	// Create the Union type
 	v := ClientMessageDataUnion{}
@@ -942,7 +942,7 @@ func ClientMessageDataUnionData8New(Data8 []byte) ClientMessageDataUnion {
 	b = 0 // always read the same bytes
 	v.Data8 = make([]byte, 20)
 	copy(v.Data8[:20], buf[b:])
-	b += xgb.Pad(int(20))
+	b += int(20)
 
 	b = 0 // always read the same bytes
 	v.Data16 = make([]uint16, 10)
@@ -950,7 +950,6 @@ func ClientMessageDataUnionData8New(Data8 []byte) ClientMessageDataUnion {
 		v.Data16[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	b = 0 // always read the same bytes
 	v.Data32 = make([]uint32, 5)
@@ -958,7 +957,6 @@ func ClientMessageDataUnionData8New(Data8 []byte) ClientMessageDataUnion {
 		v.Data32[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -972,7 +970,6 @@ func ClientMessageDataUnionData16New(Data16 []uint16) ClientMessageDataUnion {
 		xgb.Put16(buf[b:], Data16[i])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	// Create the Union type
 	v := ClientMessageDataUnion{}
@@ -982,7 +979,7 @@ func ClientMessageDataUnionData16New(Data16 []uint16) ClientMessageDataUnion {
 	b = 0 // always read the same bytes
 	v.Data8 = make([]byte, 20)
 	copy(v.Data8[:20], buf[b:])
-	b += xgb.Pad(int(20))
+	b += int(20)
 
 	b = 0 // always read the same bytes
 	v.Data16 = make([]uint16, 10)
@@ -990,7 +987,6 @@ func ClientMessageDataUnionData16New(Data16 []uint16) ClientMessageDataUnion {
 		v.Data16[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	b = 0 // always read the same bytes
 	v.Data32 = make([]uint32, 5)
@@ -998,7 +994,6 @@ func ClientMessageDataUnionData16New(Data16 []uint16) ClientMessageDataUnion {
 		v.Data32[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -1012,7 +1007,6 @@ func ClientMessageDataUnionData32New(Data32 []uint32) ClientMessageDataUnion {
 		xgb.Put32(buf[b:], Data32[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	// Create the Union type
 	v := ClientMessageDataUnion{}
@@ -1022,7 +1016,7 @@ func ClientMessageDataUnionData32New(Data32 []uint32) ClientMessageDataUnion {
 	b = 0 // always read the same bytes
 	v.Data8 = make([]byte, 20)
 	copy(v.Data8[:20], buf[b:])
-	b += xgb.Pad(int(20))
+	b += int(20)
 
 	b = 0 // always read the same bytes
 	v.Data16 = make([]uint16, 10)
@@ -1030,7 +1024,6 @@ func ClientMessageDataUnionData32New(Data32 []uint32) ClientMessageDataUnion {
 		v.Data16[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	b = 0 // always read the same bytes
 	v.Data32 = make([]uint32, 5)
@@ -1038,7 +1031,6 @@ func ClientMessageDataUnionData32New(Data32 []uint32) ClientMessageDataUnion {
 		v.Data32[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -1050,7 +1042,7 @@ func ClientMessageDataUnionRead(buf []byte, v *ClientMessageDataUnion) int {
 	b = 0 // re-read the same bytes
 	v.Data8 = make([]byte, 20)
 	copy(v.Data8[:20], buf[b:])
-	b += xgb.Pad(int(20))
+	b += int(20)
 
 	b = 0 // re-read the same bytes
 	v.Data16 = make([]uint16, 10)
@@ -1058,7 +1050,6 @@ func ClientMessageDataUnionRead(buf []byte, v *ClientMessageDataUnion) int {
 		v.Data16[i] = xgb.Get16(buf[b:])
 		b += 2
 	}
-	b = xgb.Pad(b)
 
 	b = 0 // re-read the same bytes
 	v.Data32 = make([]uint32, 5)
@@ -1066,7 +1057,6 @@ func ClientMessageDataUnionRead(buf []byte, v *ClientMessageDataUnion) int {
 		v.Data32[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return 20
 }
@@ -1089,7 +1079,7 @@ func (v ClientMessageDataUnion) Bytes() []byte {
 	b := 0
 
 	copy(buf[b:], v.Data8[:20])
-	b += xgb.Pad(int(20))
+	b += int(20)
 	return buf
 }
 
@@ -1189,7 +1179,7 @@ func (v Coloritem) Bytes() []byte {
 
 	b += 1 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // ColoritemListBytes writes a list of Coloritem values to a byte slice.
@@ -1908,7 +1898,7 @@ func (v DepthInfo) Bytes() []byte {
 
 	b += VisualInfoListBytes(buf[b:], v.Visuals)
 
-	return buf
+	return buf[:b]
 }
 
 // DepthInfoListBytes writes a list of DepthInfo values to a byte slice.
@@ -2580,7 +2570,7 @@ func (v Fontprop) Bytes() []byte {
 	xgb.Put32(buf[b:], v.Value)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // FontpropListBytes writes a list of Fontprop values to a byte slice.
@@ -2646,7 +2636,7 @@ func (v Format) Bytes() []byte {
 
 	b += 5 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // FormatListBytes writes a list of Format values to a byte slice.
@@ -3072,7 +3062,7 @@ func HostRead(buf []byte, v *Host) int {
 
 	v.Address = make([]byte, v.AddressLen)
 	copy(v.Address[:v.AddressLen], buf[b:])
-	b += xgb.Pad(int(v.AddressLen))
+	b += int(v.AddressLen)
 
 	return b
 }
@@ -3101,9 +3091,9 @@ func (v Host) Bytes() []byte {
 	b += 2
 
 	copy(buf[b:], v.Address[:v.AddressLen])
-	b += xgb.Pad(int(v.AddressLen))
+	b += int(v.AddressLen)
 
-	return buf
+	return buf[:b]
 }
 
 // HostListBytes writes a list of Host values to a byte slice.
@@ -3469,7 +3459,7 @@ func KeymapNotifyEventNew(buf []byte) xgb.Event {
 
 	v.Keys = make([]byte, 31)
 	copy(v.Keys[:31], buf[b:])
-	b += xgb.Pad(int(31))
+	b += int(31)
 
 	return v
 }
@@ -3484,7 +3474,7 @@ func (v KeymapNotifyEvent) Bytes() []byte {
 	b += 1
 
 	copy(buf[b:], v.Keys[:31])
-	b += xgb.Pad(int(31))
+	b += int(31)
 
 	return buf
 }
@@ -4323,7 +4313,7 @@ func (v Point) Bytes() []byte {
 	xgb.Put16(buf[b:], uint16(v.Y))
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // PointListBytes writes a list of Point values to a byte slice.
@@ -4506,7 +4496,7 @@ func (v Rectangle) Bytes() []byte {
 	xgb.Put16(buf[b:], v.Height)
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // RectangleListBytes writes a list of Rectangle values to a byte slice.
@@ -4831,7 +4821,7 @@ func (v Rgb) Bytes() []byte {
 
 	b += 2 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // RgbListBytes writes a list of Rgb values to a byte slice.
@@ -4997,7 +4987,7 @@ func (v ScreenInfo) Bytes() []byte {
 
 	b += DepthInfoListBytes(buf[b:], v.AllowedDepths)
 
-	return buf
+	return buf[:b]
 }
 
 // ScreenInfoListBytes writes a list of ScreenInfo values to a byte slice.
@@ -5079,7 +5069,7 @@ func (v Segment) Bytes() []byte {
 	xgb.Put16(buf[b:], uint16(v.Y2))
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // SegmentListBytes writes a list of Segment values to a byte slice.
@@ -5434,9 +5424,9 @@ func (v SetupAuthenticate) Bytes() []byte {
 	b += 2
 
 	copy(buf[b:], v.Reason[:(int(v.Length)*4)])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
-	return buf
+	return buf[:b]
 }
 
 // SetupAuthenticateListBytes writes a list of SetupAuthenticate values to a byte slice.
@@ -5529,9 +5519,9 @@ func (v SetupFailed) Bytes() []byte {
 	b += 2
 
 	copy(buf[b:], v.Reason[:v.ReasonLen])
-	b += xgb.Pad(int(v.ReasonLen))
+	b += int(v.ReasonLen)
 
-	return buf
+	return buf[:b]
 }
 
 // SetupFailedListBytes writes a list of SetupFailed values to a byte slice.
@@ -5576,9 +5566,11 @@ type SetupInfo struct {
 	MinKeycode               Keycode
 	MaxKeycode               Keycode
 	// padding: 4 bytes
-	Vendor        string       // size: xgb.Pad((int(VendorLen) * 1))
-	PixmapFormats []Format     // size: xgb.Pad((int(PixmapFormatsLen) * 8))
-	Roots         []ScreenInfo // size: ScreenInfoListSize(Roots)
+	Vendor string // size: xgb.Pad((int(VendorLen) * 1))
+	// alignment gap to multiple of 4
+	PixmapFormats []Format // size: xgb.Pad((int(PixmapFormatsLen) * 8))
+	// alignment gap to multiple of 4
+	Roots []ScreenInfo // size: ScreenInfoListSize(Roots)
 }
 
 // SetupInfoRead reads a byte slice into a SetupInfo value.
@@ -5650,9 +5642,13 @@ func SetupInfoRead(buf []byte, v *SetupInfo) int {
 		b += int(v.VendorLen)
 	}
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.PixmapFormats = make([]Format, v.PixmapFormatsLen)
 	b += FormatReadList(buf[b:], v.PixmapFormats)
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.Roots = make([]ScreenInfo, v.RootsLen)
 	b += ScreenInfoReadList(buf[b:], v.Roots)
 
@@ -5671,7 +5667,7 @@ func SetupInfoReadList(buf []byte, dest []SetupInfo) int {
 
 // Bytes writes a SetupInfo value to a byte slice.
 func (v SetupInfo) Bytes() []byte {
-	buf := make([]byte, (((40 + xgb.Pad((int(v.VendorLen) * 1))) + xgb.Pad((int(v.PixmapFormatsLen) * 8))) + ScreenInfoListSize(v.Roots)))
+	buf := make([]byte, (((((40 + xgb.Pad((int(v.VendorLen) * 1))) + 4) + xgb.Pad((int(v.PixmapFormatsLen) * 8))) + 4) + ScreenInfoListSize(v.Roots)))
 	b := 0
 
 	buf[b] = v.Status
@@ -5733,13 +5729,17 @@ func (v SetupInfo) Bytes() []byte {
 	b += 4 // padding
 
 	copy(buf[b:], v.Vendor[:v.VendorLen])
-	b += xgb.Pad(int(v.VendorLen))
+	b += int(v.VendorLen)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	b += FormatListBytes(buf[b:], v.PixmapFormats)
 
+	b = (b + 3) & ^3 // alignment gap
+
 	b += ScreenInfoListBytes(buf[b:], v.Roots)
 
-	return buf
+	return buf[:b]
 }
 
 // SetupInfoListBytes writes a list of SetupInfo values to a byte slice.
@@ -5758,7 +5758,7 @@ func SetupInfoListBytes(buf []byte, list []SetupInfo) int {
 func SetupInfoListSize(list []SetupInfo) int {
 	size := 0
 	for _, item := range list {
-		size += (((40 + xgb.Pad((int(item.VendorLen) * 1))) + xgb.Pad((int(item.PixmapFormatsLen) * 8))) + ScreenInfoListSize(item.Roots))
+		size += (((((40 + xgb.Pad((int(item.VendorLen) * 1))) + 4) + xgb.Pad((int(item.PixmapFormatsLen) * 8))) + 4) + ScreenInfoListSize(item.Roots))
 	}
 	return size
 }
@@ -5850,12 +5850,12 @@ func (v SetupRequest) Bytes() []byte {
 	b += 2 // padding
 
 	copy(buf[b:], v.AuthorizationProtocolName[:v.AuthorizationProtocolNameLen])
-	b += xgb.Pad(int(v.AuthorizationProtocolNameLen))
+	b += int(v.AuthorizationProtocolNameLen)
 
 	copy(buf[b:], v.AuthorizationProtocolData[:v.AuthorizationProtocolDataLen])
-	b += xgb.Pad(int(v.AuthorizationProtocolDataLen))
+	b += int(v.AuthorizationProtocolDataLen)
 
-	return buf
+	return buf[:b]
 }
 
 // SetupRequestListBytes writes a list of SetupRequest values to a byte slice.
@@ -5928,9 +5928,9 @@ func (v Str) Bytes() []byte {
 	b += 1
 
 	copy(buf[b:], v.Name[:v.NameLen])
-	b += xgb.Pad(int(v.NameLen))
+	b += int(v.NameLen)
 
-	return buf
+	return buf[:b]
 }
 
 // StrListBytes writes a list of Str values to a byte slice.
@@ -6009,7 +6009,7 @@ func (v Timecoord) Bytes() []byte {
 	xgb.Put16(buf[b:], uint16(v.Y))
 	b += 2
 
-	return buf
+	return buf[:b]
 }
 
 // TimecoordListBytes writes a list of Timecoord values to a byte slice.
@@ -6352,7 +6352,7 @@ func (v VisualInfo) Bytes() []byte {
 
 	b += 4 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // VisualInfoListBytes writes a list of VisualInfo values to a byte slice.
@@ -6588,7 +6588,8 @@ type AllocColorCellsReply struct {
 	MasksLen  uint16
 	// padding: 20 bytes
 	Pixels []uint32 // size: xgb.Pad((int(PixelsLen) * 4))
-	Masks  []uint32 // size: xgb.Pad((int(MasksLen) * 4))
+	// alignment gap to multiple of 4
+	Masks []uint32 // size: xgb.Pad((int(MasksLen) * 4))
 }
 
 // Reply blocks and returns the reply data for a AllocColorCells request.
@@ -6629,14 +6630,14 @@ func allocColorCellsReply(buf []byte) *AllocColorCellsReply {
 		v.Pixels[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Masks = make([]uint32, v.MasksLen)
 	for i := 0; i < int(v.MasksLen); i++ {
 		v.Masks[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -6754,7 +6755,6 @@ func allocColorPlanesReply(buf []byte) *AllocColorPlanesReply {
 		v.Pixels[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -6905,7 +6905,7 @@ func allocNamedColorRequest(c *xgb.Conn, Cmap Colormap, NameLen uint16, Name str
 	b += 2 // padding
 
 	copy(buf[b:], Name[:NameLen])
-	b += xgb.Pad(int(NameLen))
+	b += int(NameLen)
 
 	return buf
 }
@@ -7169,7 +7169,7 @@ func changeHostsRequest(c *xgb.Conn, Mode byte, Family byte, AddressLen uint16,
 	b += 2
 
 	copy(buf[b:], Address[:AddressLen])
-	b += xgb.Pad(int(AddressLen))
+	b += int(AddressLen)
 
 	return buf
 }
@@ -7282,7 +7282,6 @@ func changeKeyboardMappingRequest(c *xgb.Conn, KeycodeCount byte, FirstKeycode K
 		xgb.Put32(buf[b:], uint32(Keysyms[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -7416,7 +7415,7 @@ func changePropertyRequest(c *xgb.Conn, Mode byte, Window Window, Property Atom,
 	b += 4
 
 	copy(buf[b:], Data[:((int(DataLen)*int(Format))/8)])
-	b += xgb.Pad(int(((int(DataLen) * int(Format)) / 8)))
+	b += int(((int(DataLen) * int(Format)) / 8))
 
 	return buf
 }
@@ -8822,7 +8821,6 @@ func freeColorsRequest(c *xgb.Conn, Cmap Colormap, PlaneMask uint32, Pixels []ui
 		xgb.Put32(buf[b:], Pixels[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -9316,7 +9314,7 @@ func getImageReply(buf []byte) *GetImageReply {
 
 	v.Data = make([]byte, (int(v.Length) * 4))
 	copy(v.Data[:(int(v.Length)*4)], buf[b:])
-	b += xgb.Pad(int((int(v.Length) * 4)))
+	b += int((int(v.Length) * 4))
 
 	return v
 }
@@ -9516,7 +9514,7 @@ func getKeyboardControlReply(buf []byte) *GetKeyboardControlReply {
 
 	v.AutoRepeats = make([]byte, 32)
 	copy(v.AutoRepeats[:32], buf[b:])
-	b += xgb.Pad(int(32))
+	b += int(32)
 
 	return v
 }
@@ -9601,7 +9599,6 @@ func getKeyboardMappingReply(buf []byte) *GetKeyboardMappingReply {
 		v.Keysyms[i] = Keysym(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -9693,7 +9690,6 @@ func getModifierMappingReply(buf []byte) *GetModifierMappingReply {
 		v.Keycodes[i] = Keycode(buf[b])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -9957,7 +9953,7 @@ func getPointerMappingReply(buf []byte) *GetPointerMappingReply {
 
 	v.Map = make([]byte, v.MapLen)
 	copy(v.Map[:v.MapLen], buf[b:])
-	b += xgb.Pad(int(v.MapLen))
+	b += int(v.MapLen)
 
 	return v
 }
@@ -10051,7 +10047,7 @@ func getPropertyReply(buf []byte) *GetPropertyReply {
 
 	v.Value = make([]byte, (int(v.ValueLen) * (int(v.Format) / 8)))
 	copy(v.Value[:(int(v.ValueLen)*(int(v.Format)/8))], buf[b:])
-	b += xgb.Pad(int((int(v.ValueLen) * (int(v.Format) / 8))))
+	b += int((int(v.ValueLen) * (int(v.Format) / 8)))
 
 	return v
 }
@@ -10914,7 +10910,7 @@ func imageText8Request(c *xgb.Conn, StringLen byte, Drawable Drawable, Gc Gconte
 	b += 2
 
 	copy(buf[b:], String[:StringLen])
-	b += xgb.Pad(int(StringLen))
+	b += int(StringLen)
 
 	return buf
 }
@@ -11053,7 +11049,7 @@ func internAtomRequest(c *xgb.Conn, OnlyIfExists bool, NameLen uint16, Name stri
 	b += 2 // padding
 
 	copy(buf[b:], Name[:NameLen])
-	b += xgb.Pad(int(NameLen))
+	b += int(NameLen)
 
 	return buf
 }
@@ -11276,7 +11272,7 @@ func listFontsRequest(c *xgb.Conn, MaxNames uint16, PatternLen uint16, Pattern s
 	b += 2
 
 	copy(buf[b:], Pattern[:PatternLen])
-	b += xgb.Pad(int(PatternLen))
+	b += int(PatternLen)
 
 	return buf
 }
@@ -11434,7 +11430,7 @@ func listFontsWithInfoRequest(c *xgb.Conn, MaxNames uint16, PatternLen uint16, P
 	b += 2
 
 	copy(buf[b:], Pattern[:PatternLen])
-	b += xgb.Pad(int(PatternLen))
+	b += int(PatternLen)
 
 	return buf
 }
@@ -11590,7 +11586,6 @@ func listInstalledColormapsReply(buf []byte) *ListInstalledColormapsReply {
 		v.Cmaps[i] = Colormap(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -11682,7 +11677,6 @@ func listPropertiesReply(buf []byte) *ListPropertiesReply {
 		v.Atoms[i] = Atom(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -11812,7 +11806,7 @@ func lookupColorRequest(c *xgb.Conn, Cmap Colormap, NameLen uint16, Name string)
 	b += 2 // padding
 
 	copy(buf[b:], Name[:NameLen])
-	b += xgb.Pad(int(NameLen))
+	b += int(NameLen)
 
 	return buf
 }
@@ -12008,7 +12002,7 @@ func openFontRequest(c *xgb.Conn, Fid Font, NameLen uint16, Name string) []byte
 	b += 2 // padding
 
 	copy(buf[b:], Name[:NameLen])
-	b += xgb.Pad(int(NameLen))
+	b += int(NameLen)
 
 	return buf
 }
@@ -12441,7 +12435,7 @@ func polyText16Request(c *xgb.Conn, Drawable Drawable, Gc Gcontext, X int16, Y i
 	b += 2
 
 	copy(buf[b:], Items[:len(Items)])
-	b += xgb.Pad(int(len(Items)))
+	b += int(len(Items))
 
 	return buf
 }
@@ -12501,7 +12495,7 @@ func polyText8Request(c *xgb.Conn, Drawable Drawable, Gc Gcontext, X int16, Y in
 	b += 2
 
 	copy(buf[b:], Items[:len(Items)])
-	b += xgb.Pad(int(len(Items)))
+	b += int(len(Items))
 
 	return buf
 }
@@ -12576,7 +12570,7 @@ func putImageRequest(c *xgb.Conn, Format byte, Drawable Drawable, Gc Gcontext, W
 	b += 2 // padding
 
 	copy(buf[b:], Data[:len(Data)])
-	b += xgb.Pad(int(len(Data)))
+	b += int(len(Data))
 
 	return buf
 }
@@ -12762,7 +12756,6 @@ func queryColorsRequest(c *xgb.Conn, Cmap Colormap, Pixels []uint32) []byte {
 		xgb.Put32(buf[b:], Pixels[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -12864,7 +12857,7 @@ func queryExtensionRequest(c *xgb.Conn, NameLen uint16, Name string) []byte {
 	b += 2 // padding
 
 	copy(buf[b:], Name[:NameLen])
-	b += xgb.Pad(int(NameLen))
+	b += int(NameLen)
 
 	return buf
 }
@@ -12911,7 +12904,8 @@ type QueryFontReply struct {
 	FontDescent    int16
 	CharInfosLen   uint32
 	Properties     []Fontprop // size: xgb.Pad((int(PropertiesLen) * 8))
-	CharInfos      []Charinfo // size: xgb.Pad((int(CharInfosLen) * 12))
+	// alignment gap to multiple of 4
+	CharInfos []Charinfo // size: xgb.Pad((int(CharInfosLen) * 12))
 }
 
 // Reply blocks and returns the reply data for a QueryFont request.
@@ -12989,6 +12983,8 @@ func queryFontReply(buf []byte) *QueryFontReply {
 	v.Properties = make([]Fontprop, v.PropertiesLen)
 	b += FontpropReadList(buf[b:], v.Properties)
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.CharInfos = make([]Charinfo, v.CharInfosLen)
 	b += CharinfoReadList(buf[b:], v.CharInfos)
 
@@ -13072,7 +13068,7 @@ func queryKeymapReply(buf []byte) *QueryKeymapReply {
 
 	v.Keys = make([]byte, 32)
 	copy(v.Keys[:32], buf[b:])
-	b += xgb.Pad(int(32))
+	b += int(32)
 
 	return v
 }
@@ -13392,7 +13388,6 @@ func queryTreeReply(buf []byte) *QueryTreeReply {
 		v.Children[i] = Window(xgb.Get32(buf[b:]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -13596,7 +13591,6 @@ func rotatePropertiesRequest(c *xgb.Conn, Window Window, AtomsLen uint16, Delta
 		xgb.Put32(buf[b:], uint32(Atoms[i]))
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -13655,7 +13649,7 @@ func sendEventRequest(c *xgb.Conn, Propagate bool, Destination Window, EventMask
 	b += 4
 
 	copy(buf[b:], Event[:32])
-	b += xgb.Pad(int(32))
+	b += int(32)
 
 	return buf
 }
@@ -13861,7 +13855,7 @@ func setDashesRequest(c *xgb.Conn, Gc Gcontext, DashOffset uint16, DashesLen uin
 	b += 2
 
 	copy(buf[b:], Dashes[:DashesLen])
-	b += xgb.Pad(int(DashesLen))
+	b += int(DashesLen)
 
 	return buf
 }
@@ -14047,7 +14041,6 @@ func setModifierMappingRequest(c *xgb.Conn, KeycodesPerModifier byte, Keycodes [
 		buf[b] = byte(Keycodes[i])
 		b += 1
 	}
-	b = xgb.Pad(b)
 
 	return buf
 }
@@ -14126,7 +14119,7 @@ func setPointerMappingRequest(c *xgb.Conn, MapLen byte, Map []byte) []byte {
 	b += 2
 
 	copy(buf[b:], Map[:MapLen])
-	b += xgb.Pad(int(MapLen))
+	b += int(MapLen)
 
 	return buf
 }
@@ -14347,7 +14340,7 @@ func storeNamedColorRequest(c *xgb.Conn, Flags byte, Cmap Colormap, Pixel uint32
 	b += 2 // padding
 
 	copy(buf[b:], Name[:NameLen])
-	b += xgb.Pad(int(NameLen))
+	b += int(NameLen)
 
 	return buf
 }
diff --git a/nexgb/xproto/xproto_test.go b/nexgb/xproto/xproto_test.go
index 44d3285..a5bec71 100644
--- a/nexgb/xproto/xproto_test.go
+++ b/nexgb/xproto/xproto_test.go
@@ -204,6 +204,23 @@ func TestWindowEvents(t *testing.T) {
 	}
 }
 
+// Calls GetFontPath function, Issue #12
+func TestGetFontPath(t *testing.T) {
+	fontPathReply, err := GetFontPath(X).Reply()
+	if err != nil {
+		t.Fatalf("GetFontPath: %v", err)
+	}
+	_ = fontPathReply
+}
+
+func TestListFonts(t *testing.T) {
+	listFontsReply, err := ListFonts(X, 10, 1, "*").Reply()
+	if err != nil {
+		t.Fatalf("ListFonts: %v", err)
+	}
+	_ = listFontsReply
+}
+
 /******************************************************************************/
 // Benchmarks
 /******************************************************************************/
diff --git a/nexgb/xselinux/xselinux.go b/nexgb/xselinux/xselinux.go
index a4cd35e..87d8f98 100644
--- a/nexgb/xselinux/xselinux.go
+++ b/nexgb/xselinux/xselinux.go
@@ -100,12 +100,12 @@ func (v ListItem) Bytes() []byte {
 	b += 4
 
 	copy(buf[b:], v.ObjectContext[:v.ObjectContextLen])
-	b += xgb.Pad(int(v.ObjectContextLen))
+	b += int(v.ObjectContextLen)
 
 	copy(buf[b:], v.DataContext[:v.DataContextLen])
-	b += xgb.Pad(int(v.DataContextLen))
+	b += int(v.DataContextLen)
 
-	return buf
+	return buf[:b]
 }
 
 // ListItemListBytes writes a list of ListItem values to a byte slice.
@@ -1766,7 +1766,7 @@ func setDeviceContextRequest(c *xgb.Conn, Device uint32, ContextLen uint32, Cont
 	b += 4
 
 	copy(buf[b:], Context[:ContextLen])
-	b += xgb.Pad(int(ContextLen))
+	b += int(ContextLen)
 
 	return buf
 }
@@ -1824,7 +1824,7 @@ func setDeviceCreateContextRequest(c *xgb.Conn, ContextLen uint32, Context strin
 	b += 4
 
 	copy(buf[b:], Context[:ContextLen])
-	b += xgb.Pad(int(ContextLen))
+	b += int(ContextLen)
 
 	return buf
 }
@@ -1882,7 +1882,7 @@ func setPropertyCreateContextRequest(c *xgb.Conn, ContextLen uint32, Context str
 	b += 4
 
 	copy(buf[b:], Context[:ContextLen])
-	b += xgb.Pad(int(ContextLen))
+	b += int(ContextLen)
 
 	return buf
 }
@@ -1940,7 +1940,7 @@ func setPropertyUseContextRequest(c *xgb.Conn, ContextLen uint32, Context string
 	b += 4
 
 	copy(buf[b:], Context[:ContextLen])
-	b += xgb.Pad(int(ContextLen))
+	b += int(ContextLen)
 
 	return buf
 }
@@ -1998,7 +1998,7 @@ func setSelectionCreateContextRequest(c *xgb.Conn, ContextLen uint32, Context st
 	b += 4
 
 	copy(buf[b:], Context[:ContextLen])
-	b += xgb.Pad(int(ContextLen))
+	b += int(ContextLen)
 
 	return buf
 }
@@ -2056,7 +2056,7 @@ func setSelectionUseContextRequest(c *xgb.Conn, ContextLen uint32, Context strin
 	b += 4
 
 	copy(buf[b:], Context[:ContextLen])
-	b += xgb.Pad(int(ContextLen))
+	b += int(ContextLen)
 
 	return buf
 }
@@ -2114,7 +2114,7 @@ func setWindowCreateContextRequest(c *xgb.Conn, ContextLen uint32, Context strin
 	b += 4
 
 	copy(buf[b:], Context[:ContextLen])
-	b += xgb.Pad(int(ContextLen))
+	b += int(ContextLen)
 
 	return buf
 }
diff --git a/nexgb/xv/xv.go b/nexgb/xv/xv.go
index ec87d02..1c406b0 100644
--- a/nexgb/xv/xv.go
+++ b/nexgb/xv/xv.go
@@ -45,7 +45,8 @@ type AdaptorInfo struct {
 	NumFormats uint16
 	Type       byte
 	// padding: 1 bytes
-	Name    string   // size: xgb.Pad((int(NameSize) * 1))
+	Name string // size: xgb.Pad((int(NameSize) * 1))
+	// alignment gap to multiple of 4
 	Formats []Format // size: xgb.Pad((int(NumFormats) * 8))
 }
 
@@ -77,6 +78,8 @@ func AdaptorInfoRead(buf []byte, v *AdaptorInfo) int {
 		b += int(v.NameSize)
 	}
 
+	b = (b + 3) & ^3 // alignment gap
+
 	v.Formats = make([]Format, v.NumFormats)
 	b += FormatReadList(buf[b:], v.Formats)
 
@@ -95,7 +98,7 @@ func AdaptorInfoReadList(buf []byte, dest []AdaptorInfo) int {
 
 // Bytes writes a AdaptorInfo value to a byte slice.
 func (v AdaptorInfo) Bytes() []byte {
-	buf := make([]byte, ((12 + xgb.Pad((int(v.NameSize) * 1))) + xgb.Pad((int(v.NumFormats) * 8))))
+	buf := make([]byte, (((12 + xgb.Pad((int(v.NameSize) * 1))) + 4) + xgb.Pad((int(v.NumFormats) * 8))))
 	b := 0
 
 	xgb.Put32(buf[b:], uint32(v.BaseId))
@@ -116,11 +119,13 @@ func (v AdaptorInfo) Bytes() []byte {
 	b += 1 // padding
 
 	copy(buf[b:], v.Name[:v.NameSize])
-	b += xgb.Pad(int(v.NameSize))
+	b += int(v.NameSize)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	b += FormatListBytes(buf[b:], v.Formats)
 
-	return buf
+	return buf[:b]
 }
 
 // AdaptorInfoListBytes writes a list of AdaptorInfo values to a byte slice.
@@ -139,7 +144,7 @@ func AdaptorInfoListBytes(buf []byte, list []AdaptorInfo) int {
 func AdaptorInfoListSize(list []AdaptorInfo) int {
 	size := 0
 	for _, item := range list {
-		size += ((12 + xgb.Pad((int(item.NameSize) * 1))) + xgb.Pad((int(item.NumFormats) * 8)))
+		size += (((12 + xgb.Pad((int(item.NameSize) * 1))) + 4) + xgb.Pad((int(item.NumFormats) * 8)))
 	}
 	return size
 }
@@ -211,9 +216,9 @@ func (v AttributeInfo) Bytes() []byte {
 	b += 4
 
 	copy(buf[b:], v.Name[:v.Size])
-	b += xgb.Pad(int(v.Size))
+	b += int(v.Size)
 
-	return buf
+	return buf[:b]
 }
 
 // AttributeInfoListBytes writes a list of AttributeInfo values to a byte slice.
@@ -462,9 +467,9 @@ func (v EncodingInfo) Bytes() []byte {
 	}
 
 	copy(buf[b:], v.Name[:v.NameSize])
-	b += xgb.Pad(int(v.NameSize))
+	b += int(v.NameSize)
 
-	return buf
+	return buf[:b]
 }
 
 // EncodingInfoListBytes writes a list of EncodingInfo values to a byte slice.
@@ -532,7 +537,7 @@ func (v Format) Bytes() []byte {
 
 	b += 3 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // FormatListBytes writes a list of Format values to a byte slice.
@@ -563,8 +568,9 @@ type Image struct {
 	DataSize  uint32
 	NumPlanes uint32
 	Pitches   []uint32 // size: xgb.Pad((int(NumPlanes) * 4))
-	Offsets   []uint32 // size: xgb.Pad((int(NumPlanes) * 4))
-	Data      []byte   // size: xgb.Pad((int(DataSize) * 1))
+	// alignment gap to multiple of 4
+	Offsets []uint32 // size: xgb.Pad((int(NumPlanes) * 4))
+	Data    []byte   // size: xgb.Pad((int(DataSize) * 1))
 }
 
 // ImageRead reads a byte slice into a Image value.
@@ -591,18 +597,18 @@ func ImageRead(buf []byte, v *Image) int {
 		v.Pitches[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Offsets = make([]uint32, v.NumPlanes)
 	for i := 0; i < int(v.NumPlanes); i++ {
 		v.Offsets[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	v.Data = make([]byte, v.DataSize)
 	copy(v.Data[:v.DataSize], buf[b:])
-	b += xgb.Pad(int(v.DataSize))
+	b += int(v.DataSize)
 
 	return b
 }
@@ -619,7 +625,7 @@ func ImageReadList(buf []byte, dest []Image) int {
 
 // Bytes writes a Image value to a byte slice.
 func (v Image) Bytes() []byte {
-	buf := make([]byte, (((16 + xgb.Pad((int(v.NumPlanes) * 4))) + xgb.Pad((int(v.NumPlanes) * 4))) + xgb.Pad((int(v.DataSize) * 1))))
+	buf := make([]byte, ((((16 + xgb.Pad((int(v.NumPlanes) * 4))) + 4) + xgb.Pad((int(v.NumPlanes) * 4))) + xgb.Pad((int(v.DataSize) * 1))))
 	b := 0
 
 	xgb.Put32(buf[b:], v.Id)
@@ -641,18 +647,18 @@ func (v Image) Bytes() []byte {
 		xgb.Put32(buf[b:], v.Pitches[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	for i := 0; i < int(v.NumPlanes); i++ {
 		xgb.Put32(buf[b:], v.Offsets[i])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	copy(buf[b:], v.Data[:v.DataSize])
-	b += xgb.Pad(int(v.DataSize))
+	b += int(v.DataSize)
 
-	return buf
+	return buf[:b]
 }
 
 // ImageListBytes writes a list of Image values to a byte slice.
@@ -671,7 +677,7 @@ func ImageListBytes(buf []byte, list []Image) int {
 func ImageListSize(list []Image) int {
 	size := 0
 	for _, item := range list {
-		size += (((16 + xgb.Pad((int(item.NumPlanes) * 4))) + xgb.Pad((int(item.NumPlanes) * 4))) + xgb.Pad((int(item.DataSize) * 1)))
+		size += ((((16 + xgb.Pad((int(item.NumPlanes) * 4))) + 4) + xgb.Pad((int(item.NumPlanes) * 4))) + xgb.Pad((int(item.DataSize) * 1)))
 	}
 	return size
 }
@@ -723,7 +729,7 @@ func ImageFormatInfoRead(buf []byte, v *ImageFormatInfo) int {
 
 	v.Guid = make([]byte, 16)
 	copy(v.Guid[:16], buf[b:])
-	b += xgb.Pad(int(16))
+	b += int(16)
 
 	v.Bpp = buf[b]
 	b += 1
@@ -781,7 +787,7 @@ func ImageFormatInfoRead(buf []byte, v *ImageFormatInfo) int {
 
 	v.VcompOrder = make([]byte, 32)
 	copy(v.VcompOrder[:32], buf[b:])
-	b += xgb.Pad(int(32))
+	b += int(32)
 
 	v.VscanlineOrder = buf[b]
 	b += 1
@@ -818,7 +824,7 @@ func (v ImageFormatInfo) Bytes() []byte {
 	b += 2 // padding
 
 	copy(buf[b:], v.Guid[:16])
-	b += xgb.Pad(int(16))
+	b += int(16)
 
 	buf[b] = v.Bpp
 	b += 1
@@ -875,14 +881,14 @@ func (v ImageFormatInfo) Bytes() []byte {
 	b += 4
 
 	copy(buf[b:], v.VcompOrder[:32])
-	b += xgb.Pad(int(32))
+	b += int(32)
 
 	buf[b] = v.VscanlineOrder
 	b += 1
 
 	b += 11 // padding
 
-	return buf
+	return buf[:b]
 }
 
 // ImageFormatInfoListBytes writes a list of ImageFormatInfo values to a byte slice.
@@ -1052,7 +1058,7 @@ func (v Rational) Bytes() []byte {
 	xgb.Put32(buf[b:], uint32(v.Denominator))
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // RationalListBytes writes a list of Rational values to a byte slice.
@@ -1730,7 +1736,7 @@ func putImageRequest(c *xgb.Conn, Port Port, Drawable xproto.Drawable, Gc xproto
 	b += 2
 
 	copy(buf[b:], Data[:len(Data)])
-	b += xgb.Pad(int(len(Data)))
+	b += int(len(Data))
 
 	return buf
 }
@@ -2335,6 +2341,7 @@ type QueryImageAttributesReply struct {
 	Height    uint16
 	// padding: 12 bytes
 	Pitches []uint32 // size: xgb.Pad((int(NumPlanes) * 4))
+	// alignment gap to multiple of 4
 	Offsets []uint32 // size: xgb.Pad((int(NumPlanes) * 4))
 }
 
@@ -2382,14 +2389,14 @@ func queryImageAttributesReply(buf []byte) *QueryImageAttributesReply {
 		v.Pitches[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
+
+	b = (b + 3) & ^3 // alignment gap
 
 	v.Offsets = make([]uint32, v.NumPlanes)
 	for i := 0; i < int(v.NumPlanes); i++ {
 		v.Offsets[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
diff --git a/nexgb/xvmc/xvmc.go b/nexgb/xvmc/xvmc.go
index cd82b33..a574a21 100644
--- a/nexgb/xvmc/xvmc.go
+++ b/nexgb/xvmc/xvmc.go
@@ -156,7 +156,7 @@ func (v SurfaceInfo) Bytes() []byte {
 	xgb.Put32(buf[b:], v.Flags)
 	b += 4
 
-	return buf
+	return buf[:b]
 }
 
 // SurfaceInfoListBytes writes a list of SurfaceInfo values to a byte slice.
@@ -275,7 +275,6 @@ func createContextReply(buf []byte) *CreateContextReply {
 		v.PrivData[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -397,7 +396,7 @@ func createSubpictureReply(buf []byte) *CreateSubpictureReply {
 
 	v.ComponentOrder = make([]byte, 4)
 	copy(v.ComponentOrder[:4], buf[b:])
-	b += xgb.Pad(int(4))
+	b += int(4)
 
 	b += 12 // padding
 
@@ -406,7 +405,6 @@ func createSubpictureReply(buf []byte) *CreateSubpictureReply {
 		v.PrivData[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }
@@ -513,7 +511,6 @@ func createSurfaceReply(buf []byte) *CreateSurfaceReply {
 		v.PrivData[i] = xgb.Get32(buf[b:])
 		b += 4
 	}
-	b = xgb.Pad(b)
 
 	return v
 }