/
decode.go
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/
decode.go
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// Copyright 2017 drillbits
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package xcs
import (
"errors"
"fmt"
"github.com/drillbits/go-arib/arib/xcs/graphicset"
"golang.org/x/text/transform"
)
var errInvalidARIBXCS = errors.New("arib: invalid external character set encoding")
func newXCSDecoder() *xcsDecoder {
d := &xcsDecoder{}
d.init()
return d
}
type xcsDecoder struct {
buf []byte
G [4]graphicset.GraphicSet // G0, G1, G2, G3
gl int
gr int
SS graphicset.GraphicSet
isSmallSize bool
}
func (d *xcsDecoder) GL() graphicset.GraphicSet {
return d.G[d.gl]
}
func (d *xcsDecoder) GR() graphicset.GraphicSet {
return d.G[d.gr]
}
func (d *xcsDecoder) Reset() {
d.init()
}
func (d *xcsDecoder) init() {
d.buf = nil
d.G = [4]graphicset.GraphicSet{
graphicset.GSetMap[graphicset.Kanji],
graphicset.GSetMap[graphicset.Alphanumeric],
graphicset.GSetMap[graphicset.Hiragana],
graphicset.GSetMap[graphicset.Katakana], // TODO: Macro?
}
d.gl = 0
d.gr = 2
}
func (d *xcsDecoder) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
d.buf = src
size := 0
loop:
for ; nSrc < len(d.buf); nSrc += size {
var buf []byte
switch b := d.buf[nSrc]; {
case b <= SP:
buf, size, err = d.readC0(nSrc)
case b < DEL:
buf, size, err = d.readGL(nSrc)
case b <= CC1000:
buf, size, err = d.readC1(nSrc)
case b != CC1515:
buf, size, err = d.readGR(nSrc)
default:
err = errInvalidARIBXCS
}
if err != nil {
break loop
}
if nDst+len(buf) > len(dst) {
err = transform.ErrShortDst
break loop
}
nDst += copy(dst[nDst:], buf)
}
if atEOF && err == transform.ErrShortSrc {
err = errInvalidARIBXCS
}
return nDst, nSrc, err
}
func (d *xcsDecoder) readC0(pos int) ([]byte, int, error) {
return d.readControlSet(pos)
}
func (d *xcsDecoder) readC1(pos int) ([]byte, int, error) {
return d.readControlSet(pos)
}
func (d *xcsDecoder) readControlSet(pos int) ([]byte, int, error) {
buf, size, err := []byte{}, 1, error(nil)
switch d.buf[pos] {
case LS1:
d.gl = 1
case LS0:
d.gl = 0
case PAPF:
// skip with parameter
size++
case SS2:
d.SS = d.G[2]
case ESC:
buf, size, err = d.readESC(pos)
case APS:
// skip with parameter
size += 2
case SS3:
d.SS = d.G[3]
case SP:
if d.isSmallSize {
buf = []byte(" ")
}
buf = []byte(" ")
case SSZ, MSZ:
d.isSmallSize = true
case NSZ:
d.isSmallSize = false
case SZX:
p1 := d.paramOrNil(pos, 1)
size++
d.isSmallSize = p1 == 0x60
case COL:
// skip with parameter
p1 := d.paramOrNil(pos, 1)
size++
if p1 == 0x20 {
// more parameter
size++
}
case FLC, POL, WMM, HLC, RPC:
// skip with parameter
size++
case MACRO:
// TODO: test
for i := pos + 1; d.paramOrNil(pos, i) != 0x4F; i++ {
size++
}
case CSI:
// TODO
// return d.readCSI(src, n)
case TIME:
// TODO: test
p1 := d.paramOrNil(pos, 1)
size++
if p1 == 0x20 {
// skip with parameter
size++
} else {
for i := pos + 2; ; i++ {
p := d.paramOrNil(pos, i)
if p < 0x40 && p > 0x43 {
size++
} else {
break
}
}
}
default:
// skip
}
return buf, size, err
}
func (d *xcsDecoder) readESC(pos int) ([]byte, int, error) {
size, err := 1, error(nil)
p1 := d.paramOrNil(pos, 1)
size++
switch {
case p1 == 0x24 || (p1 >= 0x28 && p1 <= 0x2B):
var gi int
var gs graphicset.GraphicSet
size, gi, gs = d.designateGraphicSet(pos)
d.G[gi] = gs
case p1 == 0x6E:
d.gl = 2
case p1 == 0x6F:
d.gl = 3
case p1 == 0x7E:
d.gr = 1
case p1 == 0x7D:
d.gr = 2
case p1 == 0x7C:
d.gr = 3
default:
size = 1
err = fmt.Errorf("arib: ESC has invalid parameter 0x%02X", p1)
}
return nil, size, err
}
// designateGraphicSet reports size of code with parameters, the index of code
// element to be designated and the key of graphic set.
func (d *xcsDecoder) designateGraphicSet(pos int) (size, gi int, gs graphicset.GraphicSet) {
size = 1 // ESC
p1 := d.paramOrNil(pos, 1)
size++
switch p1 {
case 0x28, 0x29, 0x2A, 0x2B:
// 1 byte charset
gi = int(p1 - 0x28)
p2 := d.paramOrNil(pos, 2)
size++
switch p2 {
case 0x20:
// DRCS
p3 := d.paramOrNil(pos, 3)
gs = graphicset.DRCSMap[p3]
size++
default:
// G set
gs = graphicset.GSetMap[p2]
}
case 0x24:
// 2 byte charset
p2 := d.paramOrNil(pos, 2)
size++
switch p2 {
case 0x28, 0x29, 0x2A, 0x2B:
gi = int(p2 - 0x28)
p3 := d.paramOrNil(pos, 3)
size++
switch p3 {
case 0x20:
// DRCS
p4 := d.paramOrNil(pos, 4)
size++
gs = graphicset.DRCSMap[p4]
default:
// G set
if p2 == 0x28 {
gs = graphicset.GSetMap[p2]
size--
} else {
gs = graphicset.GSetMap[p3]
}
}
default:
// G set
gi = 0
gs = graphicset.GSetMap[p2]
}
}
return
}
func (d *xcsDecoder) readGL(n int) ([]byte, int, error) {
// SingleShift
var gs graphicset.GraphicSet
if d.SS != nil {
gs = d.SS
d.SS = nil
} else {
gs = d.GL()
}
b, size := gs.Get(d.byteOrNil(n), d.byteOrNil(n+1))
return b, size, nil
}
func (d *xcsDecoder) readGR(n int) ([]byte, int, error) {
b, size := d.GR().Get(d.byteOrNil(n)&0x7F, d.byteOrNil(n+1)&0x7F)
return b, size, nil
}
func (d *xcsDecoder) byteOrNil(pos int) byte {
if pos < len(d.buf) {
return d.buf[pos]
}
return 0x00
}
func (d *xcsDecoder) paramOrNil(pos, n int) byte {
if pos+n < len(d.buf) {
return d.buf[pos+n]
}
return 0x00
}