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audio/mp3: Remove global variable 'theSideInfo'

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This commit is contained in:
Hajime Hoshi 2017-06-18 01:32:44 +09:00
parent 9890a530a2
commit 93c48e15c0
1 changed files with 34 additions and 34 deletions
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68
audio/mp3/sideinfo.go
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@ -60,40 +60,41 @@ func (f *frame) readAudioL3() error {
main_data_size -= 2 main_data_size -= 2
} }
/* Read sideinfo from bitstream into buffer used by getSideBits() */ /* Read sideinfo from bitstream into buffer used by getSideBits() */
if err := getSideinfo(sideinfo_size); err != nil { s, err := getSideinfo(sideinfo_size)
if err != nil {
return err return err
} }
/* Parse audio data */ /* Parse audio data */
/* Pointer to where we should start reading main data */ /* Pointer to where we should start reading main data */
f.sideInfo.main_data_begin = getSideBits(9) f.sideInfo.main_data_begin = s.getSideBits(9)
/* Get private bits. Not used for anything. */ /* Get private bits. Not used for anything. */
if f.header.mode == mpeg1ModeSingleChannel { if f.header.mode == mpeg1ModeSingleChannel {
f.sideInfo.private_bits = getSideBits(5) f.sideInfo.private_bits = s.getSideBits(5)
} else { } else {
f.sideInfo.private_bits = getSideBits(3) f.sideInfo.private_bits = s.getSideBits(3)
} }
/* Get scale factor selection information */ /* Get scale factor selection information */
for ch := 0; ch < nch; ch++ { for ch := 0; ch < nch; ch++ {
for scfsi_band := 0; scfsi_band < 4; scfsi_band++ { for scfsi_band := 0; scfsi_band < 4; scfsi_band++ {
f.sideInfo.scfsi[ch][scfsi_band] = getSideBits(1) f.sideInfo.scfsi[ch][scfsi_band] = s.getSideBits(1)
} }
} }
/* Get the rest of the side information */ /* Get the rest of the side information */
for gr := 0; gr < 2; gr++ { for gr := 0; gr < 2; gr++ {
for ch := 0; ch < nch; ch++ { for ch := 0; ch < nch; ch++ {
f.sideInfo.part2_3_length[gr][ch] = getSideBits(12) f.sideInfo.part2_3_length[gr][ch] = s.getSideBits(12)
f.sideInfo.big_values[gr][ch] = getSideBits(9) f.sideInfo.big_values[gr][ch] = s.getSideBits(9)
f.sideInfo.global_gain[gr][ch] = getSideBits(8) f.sideInfo.global_gain[gr][ch] = s.getSideBits(8)
f.sideInfo.scalefac_compress[gr][ch] = getSideBits(4) f.sideInfo.scalefac_compress[gr][ch] = s.getSideBits(4)
f.sideInfo.win_switch_flag[gr][ch] = getSideBits(1) f.sideInfo.win_switch_flag[gr][ch] = s.getSideBits(1)
if f.sideInfo.win_switch_flag[gr][ch] == 1 { if f.sideInfo.win_switch_flag[gr][ch] == 1 {
f.sideInfo.block_type[gr][ch] = getSideBits(2) f.sideInfo.block_type[gr][ch] = s.getSideBits(2)
f.sideInfo.mixed_block_flag[gr][ch] = getSideBits(1) f.sideInfo.mixed_block_flag[gr][ch] = s.getSideBits(1)
for region := 0; region < 2; region++ { for region := 0; region < 2; region++ {
f.sideInfo.table_select[gr][ch][region] = getSideBits(5) f.sideInfo.table_select[gr][ch][region] = s.getSideBits(5)
} }
for window := 0; window < 3; window++ { for window := 0; window < 3; window++ {
f.sideInfo.subblock_gain[gr][ch][window] = getSideBits(3) f.sideInfo.subblock_gain[gr][ch][window] = s.getSideBits(3)
} }
if (f.sideInfo.block_type[gr][ch] == 2) && (f.sideInfo.mixed_block_flag[gr][ch] == 0) { if (f.sideInfo.block_type[gr][ch] == 2) && (f.sideInfo.mixed_block_flag[gr][ch] == 0) {
f.sideInfo.region0_count[gr][ch] = 8 /* Implicit */ f.sideInfo.region0_count[gr][ch] = 8 /* Implicit */
@ -104,15 +105,15 @@ func (f *frame) readAudioL3() error {
f.sideInfo.region1_count[gr][ch] = 20 - f.sideInfo.region0_count[gr][ch] f.sideInfo.region1_count[gr][ch] = 20 - f.sideInfo.region0_count[gr][ch]
} else { } else {
for region := 0; region < 3; region++ { for region := 0; region < 3; region++ {
f.sideInfo.table_select[gr][ch][region] = getSideBits(5) f.sideInfo.table_select[gr][ch][region] = s.getSideBits(5)
} }
f.sideInfo.region0_count[gr][ch] = getSideBits(4) f.sideInfo.region0_count[gr][ch] = s.getSideBits(4)
f.sideInfo.region1_count[gr][ch] = getSideBits(3) f.sideInfo.region1_count[gr][ch] = s.getSideBits(3)
f.sideInfo.block_type[gr][ch] = 0 /* Implicit */ f.sideInfo.block_type[gr][ch] = 0 /* Implicit */
} }
f.sideInfo.preflag[gr][ch] = getSideBits(1) f.sideInfo.preflag[gr][ch] = s.getSideBits(1)
f.sideInfo.scalefac_scale[gr][ch] = getSideBits(1) f.sideInfo.scalefac_scale[gr][ch] = s.getSideBits(1)
f.sideInfo.count1table_select[gr][ch] = getSideBits(1) f.sideInfo.count1table_select[gr][ch] = s.getSideBits(1)
} }
} }
return nil return nil
@ -124,9 +125,7 @@ type sideInfo struct {
idx int // Index into the current byte(0-7) idx int // Index into the current byte(0-7)
} }
var theSideInfo sideInfo func getSideinfo(size int) (*sideInfo, error) {
func getSideinfo(size int) error {
buf := make([]int, size) buf := make([]int, size)
n := 0 n := 0
var err error var err error
@ -137,32 +136,33 @@ func getSideinfo(size int) error {
} }
if n < size { if n < size {
if err == io.EOF { if err == io.EOF {
return fmt.Errorf("mp3: unexpected EOF at getSideinfo") return nil, fmt.Errorf("mp3: unexpected EOF at getSideinfo")
} }
return fmt.Errorf("mp3: couldn't read sideinfo %d bytes at pos %d: %v", return nil, fmt.Errorf("mp3: couldn't read sideinfo %d bytes at pos %d: %v",
size, getFilepos(), err) size, getFilepos(), err)
} }
theSideInfo.vec = buf[:n] s := &sideInfo{
theSideInfo.idx = 0 vec: buf[:n],
return nil }
return s, nil
} }
func getSideBits(num int) int { func (s *sideInfo) getSideBits(num int) int {
// Form a word of the next four bytes // Form a word of the next four bytes
// TODO: endianness? // TODO: endianness?
b := make([]int, 4) b := make([]int, 4)
for i := range b { for i := range b {
if len(theSideInfo.vec) > i { if len(s.vec) > i {
b[i] = theSideInfo.vec[i] b[i] = s.vec[i]
} }
} }
tmp := (uint32(b[0]) << 24) | (uint32(b[1]) << 16) | (uint32(b[2]) << 8) | (uint32(b[3]) << 0) tmp := (uint32(b[0]) << 24) | (uint32(b[1]) << 16) | (uint32(b[2]) << 8) | (uint32(b[3]) << 0)
// Remove bits already used // Remove bits already used
tmp = tmp << uint(theSideInfo.idx) tmp = tmp << uint(s.idx)
// Remove bits after the desired bits // Remove bits after the desired bits
tmp = tmp >> (32 - uint(num)) tmp = tmp >> (32 - uint(num))
// Update pointers // Update pointers
theSideInfo.vec = theSideInfo.vec[(theSideInfo.idx+int(num))>>3:] s.vec = s.vec[(s.idx+int(num))>>3:]
theSideInfo.idx = (theSideInfo.idx + int(num)) & 0x07 s.idx = (s.idx + int(num)) & 0x07
return int(tmp) return int(tmp)
} }