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authorPřemysl Janouch <p@janouch.name>2019-04-12 02:15:28 +0200
committerPřemysl Janouch <p@janouch.name>2019-04-12 02:31:22 +0200
commitc9e5b4d1e9affe3309fc2eae2aed73bc554117b9 (patch)
tree0ce08688143cef43809fde4831639e486b8a5b43 /ql
parente605078d8932fd76979cad6e923257e4f190a89b (diff)
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Create a package for the printer
Diffstat (limited to 'ql')
-rw-r--r--ql/ql.go218
1 files changed, 218 insertions, 0 deletions
diff --git a/ql/ql.go b/ql/ql.go
new file mode 100644
index 0000000..9f507da
--- /dev/null
+++ b/ql/ql.go
@@ -0,0 +1,218 @@
+// Package ql is a Linux driver for Brother QL-series printers.
+package ql
+
+// Resources:
+// http://www.undocprint.org/formats/page_description_languages/brother_p-touch
+
+import (
+ "errors"
+ "io"
+ "os"
+ "path/filepath"
+ "regexp"
+ "strings"
+ "syscall"
+ "time"
+ "unsafe"
+)
+
+// #include <linux/ioctl.h>
+import "C"
+
+// -----------------------------------------------------------------------------
+
+func _IOC(dir, typ, nr, size int) uintptr {
+ return (uintptr(dir) << C._IOC_DIRSHIFT) |
+ (uintptr(typ) << C._IOC_TYPESHIFT) |
+ (uintptr(nr) << C._IOC_NRSHIFT) |
+ (uintptr(size) << C._IOC_SIZESHIFT)
+}
+
+const (
+ iocnrGetDeviceID = 1
+)
+
+// lpiocGetDeviceID reads the IEEE-1284 Device ID string of a printer.
+func lpiocGetDeviceID(fd uintptr) ([]byte, error) {
+ var buf [1024]byte
+ if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd,
+ _IOC(C._IOC_READ, 'P', iocnrGetDeviceID, len(buf)),
+ uintptr(unsafe.Pointer(&buf))); err != 0 {
+ return nil, err
+ }
+
+ // In theory it might get trimmed along the way.
+ length := int(buf[0])<<8 | int(buf[1])
+ if 2+length > len(buf) {
+ return buf[2:], errors.New("the device ID string got trimmed")
+ }
+
+ return buf[2 : 2+length], nil
+}
+
+// -----------------------------------------------------------------------------
+
+var deviceIDRegexp = regexp.MustCompile(
+ `(?s:\s*([^:,;]+?)\s*:\s*([^:;]*)\s*(?:;|$))`)
+
+type deviceID map[string][]string
+
+// parseIEEE1284DeviceID leniently parses an IEEE 1284 Device ID string
+// and returns a map containing a slice of values for each key.
+//
+// See e.g. http://www.undocprint.org/formats/communication_protocols/ieee_1284
+func parseIEEE1284DeviceID(id []byte) deviceID {
+ m := make(deviceID)
+ for _, kv := range deviceIDRegexp.FindAllStringSubmatch(string(id), -1) {
+ var values []string
+ for _, v := range strings.Split(kv[2], ",") {
+ values = append(values, strings.Trim(v, "\t\n\v\f\r "))
+ }
+ m[kv[1]] = values
+ }
+ return m
+}
+
+func (id deviceID) Find(key, abbreviation string) []string {
+ if values, ok := id[key]; ok {
+ return values
+ }
+ if values, ok := id[abbreviation]; ok {
+ return values
+ }
+ return nil
+}
+
+// -----------------------------------------------------------------------------
+
+type Printer struct {
+ File *os.File
+}
+
+func compatible(id deviceID) bool {
+ for _, commandSet := range id.Find("COMMAND SET", "CMD") {
+ if commandSet == "PT-CBP" {
+ return true
+ }
+ }
+ return false
+}
+
+// Open finds and initializes the first USB printer found supporting
+// the appropriate protocol. Returns nil if no printer could be found.
+func Open() (*Printer, error) {
+ // Linux usblp module, located in /drivers/usb/class/usblp.c
+ paths, err := filepath.Glob("/dev/usb/lp[0-9]*")
+ if err != nil {
+ return nil, err
+ }
+ for _, candidate := range paths {
+ f, err := os.OpenFile(candidate, os.O_RDWR, 0)
+ if err != nil {
+ continue
+ }
+ // Filter out obvious non-printers.
+ deviceID, err := lpiocGetDeviceID(f.Fd())
+ if err != nil {
+ f.Close()
+ continue
+ }
+ // Filter out printers that wouldn't understand the protocol.
+ if !compatible(parseIEEE1284DeviceID(deviceID)) {
+ f.Close()
+ continue
+ }
+ return &Printer{File: f}, nil
+ }
+ return nil, nil
+}
+
+// Initialize initializes the printer for further operations.
+func (p *Printer) Initialize() error {
+ // Clear the print buffer.
+ invalidate := make([]byte, 400)
+ if _, err := p.File.Write(invalidate); err != nil {
+ return err
+ }
+
+ // Initialize.
+ if _, err := p.File.WriteString("\x1b\x40"); err != nil {
+ return err
+ }
+
+ // Flush any former responses in the printer's queue.
+ //
+ // I'm not sure if this is necessary, or rather whether the kernel driver
+ // does any buffering that could cause data to be returned at this point.
+ /*
+ for {
+ dummy := make([]byte, 32)
+ if _, err := f.Read(dummy); err == io.EOF {
+ break
+ }
+ }
+ */
+
+ return nil
+}
+
+// GetStatus retrieves the printer's status as raw data. The printer must be
+// in an appropriate mode, i.e. on-line and not currently printing.
+func (p *Printer) GetStatus() ([]byte, error) {
+ // Request status information.
+ if _, err := p.File.WriteString("\x1b\x69\x53"); err != nil {
+ return nil, err
+ }
+
+ // We need to poll the device a bit.
+ status := make([]byte, 32)
+ start := time.Now()
+ for {
+ if n, err := p.File.Read(status); err == io.EOF {
+ time.Sleep(10 * time.Millisecond)
+ } else if err != nil {
+ return nil, err
+ } else if n < 32 {
+ return nil, errors.New("invalid read")
+ } else {
+ return status, nil
+ }
+ if time.Now().Sub(start) > time.Second {
+ return nil, errors.New("timeout")
+ }
+ }
+}
+
+// Close closes the underlying file.
+func (p *Printer) Close() error {
+ return p.File.Close()
+}
+
+// -----------------------------------------------------------------------------
+
+type Status struct {
+ errors []string
+}
+
+func decodeBitfieldErrors(b byte, errors [8]string) []string {
+ var result []string
+ for i := uint(0); i < 8; i++ {
+ if b&(1<<i) != 0 {
+ result = append(result, errors[i])
+ }
+ }
+ return result
+}
+
+// TODO: What exactly do we need? Probably extend as needed.
+func decodeStatusInformation(d []byte) Status {
+ var status Status
+ status.errors = append(status.errors, decodeBitfieldErrors(d[8], [8]string{
+ "no media", "end of media", "cutter jam", "?", "printer in use",
+ "printer turned off", "high-voltage adapter", "fan motor error"})...)
+ status.errors = append(status.errors, decodeBitfieldErrors(d[9], [8]string{
+ "replace media", "expansion buffer full", "communication error",
+ "communication buffer full", "cover open", "cancel key",
+ "media cannot be fed", "system error"})...)
+ return status
+}