From a548d9d0f7b889627c43b18811357fad88760b2d Mon Sep 17 00:00:00 2001 From: aarzilli Date: Fri, 2 May 2014 15:09:23 +0200 Subject: Fix Issue #21: automatic calculation of alignment padding after lists --- nexgb/xgbgen/aligngap.go | 130 +++++++++++++++++++++++++++++++++++++++ nexgb/xgbgen/context.go | 2 + nexgb/xgbgen/field.go | 32 ++++++---- nexgb/xgbgen/go.go | 18 +++++- nexgb/xgbgen/go_list.go | 10 +-- nexgb/xgbgen/go_request_reply.go | 30 ++++++--- nexgb/xgbgen/go_struct.go | 2 +- nexgb/xgbgen/request_reply.go | 12 ++-- nexgb/xgbgen/size.go | 13 ++-- nexgb/xgbgen/translation.go | 2 +- nexgb/xgbgen/type.go | 12 ++-- 11 files changed, 211 insertions(+), 52 deletions(-) create mode 100644 nexgb/xgbgen/aligngap.go (limited to 'nexgb/xgbgen') 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()) } -- cgit v1.2.3