diff --git a/libavcodec/mpc7.c b/libavcodec/mpc7.c index 28b51922ec..5d749106de 100644 --- a/libavcodec/mpc7.c +++ b/libavcodec/mpc7.c @@ -28,8 +28,9 @@ #include "libavutil/channel_layout.h" #include "libavutil/internal.h" #include "libavutil/lfg.h" + #include "avcodec.h" -#include "get_bits.h" +#include "bitstream.h" #include "internal.h" #include "mpegaudiodsp.h" @@ -53,7 +54,7 @@ static av_cold int mpc7_decode_init(AVCodecContext * avctx) { int i, j; MPCContext *c = avctx->priv_data; - GetBitContext gb; + BitstreamContext bc; LOCAL_ALIGNED_16(uint8_t, buf, [16]); static int vlc_initialized = 0; @@ -78,18 +79,18 @@ static av_cold int mpc7_decode_init(AVCodecContext * avctx) ff_mpadsp_init(&c->mpadsp); c->bdsp.bswap_buf((uint32_t *) buf, (const uint32_t *) avctx->extradata, 4); ff_mpc_init(); - init_get_bits(&gb, buf, 128); + bitstream_init(&bc, buf, 128); - c->IS = get_bits1(&gb); - c->MSS = get_bits1(&gb); - c->maxbands = get_bits(&gb, 6); + c->IS = bitstream_read_bit(&bc); + c->MSS = bitstream_read_bit(&bc); + c->maxbands = bitstream_read(&bc, 6); if(c->maxbands >= BANDS){ av_log(avctx, AV_LOG_ERROR, "Too many bands: %i\n", c->maxbands); return -1; } - skip_bits_long(&gb, 88); - c->gapless = get_bits1(&gb); - c->lastframelen = get_bits(&gb, 11); + bitstream_skip(&bc, 88); + c->gapless = bitstream_read_bit(&bc); + c->lastframelen = bitstream_read(&bc, 11); av_log(avctx, AV_LOG_DEBUG, "IS: %d, MSS: %d, TG: %d, LFL: %d, bands: %d\n", c->IS, c->MSS, c->gapless, c->lastframelen, c->maxbands); c->frames_to_skip = 0; @@ -143,7 +144,7 @@ static av_cold int mpc7_decode_init(AVCodecContext * avctx) /** * Fill samples for given subband */ -static inline void idx_to_quant(MPCContext *c, GetBitContext *gb, int idx, int *dst) +static inline void idx_to_quant(MPCContext *c, BitstreamContext *bc, int idx, int *dst) { int i, i1, t; switch(idx){ @@ -153,43 +154,43 @@ static inline void idx_to_quant(MPCContext *c, GetBitContext *gb, int idx, int * } break; case 1: - i1 = get_bits1(gb); + i1 = bitstream_read_bit(bc); for(i = 0; i < SAMPLES_PER_BAND/3; i++){ - t = get_vlc2(gb, quant_vlc[0][i1].table, 9, 2); + t = bitstream_read_vlc(bc, quant_vlc[0][i1].table, 9, 2); *dst++ = mpc7_idx30[t]; *dst++ = mpc7_idx31[t]; *dst++ = mpc7_idx32[t]; } break; case 2: - i1 = get_bits1(gb); + i1 = bitstream_read_bit(bc); for(i = 0; i < SAMPLES_PER_BAND/2; i++){ - t = get_vlc2(gb, quant_vlc[1][i1].table, 9, 2); + t = bitstream_read_vlc(bc, quant_vlc[1][i1].table, 9, 2); *dst++ = mpc7_idx50[t]; *dst++ = mpc7_idx51[t]; } break; case 3: case 4: case 5: case 6: case 7: - i1 = get_bits1(gb); + i1 = bitstream_read_bit(bc); for(i = 0; i < SAMPLES_PER_BAND; i++) - *dst++ = get_vlc2(gb, quant_vlc[idx-1][i1].table, 9, 2) - mpc7_quant_vlc_off[idx-1]; + *dst++ = bitstream_read_vlc(bc, quant_vlc[idx - 1][i1].table, 9, 2) - mpc7_quant_vlc_off[idx - 1]; break; case 8: case 9: case 10: case 11: case 12: case 13: case 14: case 15: case 16: case 17: t = (1 << (idx - 2)) - 1; for(i = 0; i < SAMPLES_PER_BAND; i++) - *dst++ = get_bits(gb, idx - 1) - t; + *dst++ = bitstream_read(bc, idx - 1) - t; break; default: // case 0 and -2..-17 return; } } -static int get_scale_idx(GetBitContext *gb, int ref) +static int get_scale_idx(BitstreamContext *bc, int ref) { - int t = get_vlc2(gb, dscf_vlc.table, MPC7_DSCF_BITS, 1) - 7; + int t = bitstream_read_vlc(bc, dscf_vlc.table, MPC7_DSCF_BITS, 1) - 7; if (t == 8) - return get_bits(gb, 6); + return bitstream_read(bc, 6); return av_clip_uintp2(ref + t, 7); } @@ -200,7 +201,7 @@ static int mpc7_decode_frame(AVCodecContext * avctx, void *data, const uint8_t *buf = avpkt->data; int buf_size; MPCContext *c = avctx->priv_data; - GetBitContext gb; + BitstreamContext bc; int i, ch; int mb = -1; Band *bands = c->bands; @@ -237,45 +238,49 @@ static int mpc7_decode_frame(AVCodecContext * avctx, void *data, return AVERROR(ENOMEM); c->bdsp.bswap_buf((uint32_t *) c->bits, (const uint32_t *) buf, buf_size >> 2); - init_get_bits(&gb, c->bits, buf_size * 8); - skip_bits_long(&gb, skip); + bitstream_init(&bc, c->bits, buf_size * 8); + bitstream_skip(&bc, skip); /* read subband indexes */ for(i = 0; i <= c->maxbands; i++){ for(ch = 0; ch < 2; ch++){ int t = 4; - if(i) t = get_vlc2(&gb, hdr_vlc.table, MPC7_HDR_BITS, 1) - 5; - if(t == 4) bands[i].res[ch] = get_bits(&gb, 4); + if (i) + t = bitstream_read_vlc(&bc, hdr_vlc.table, MPC7_HDR_BITS, 1) - 5; + if (t == 4) + bands[i].res[ch] = bitstream_read(&bc, 4); else bands[i].res[ch] = av_clip(bands[i-1].res[ch] + t, 0, 17); } if(bands[i].res[0] || bands[i].res[1]){ mb = i; - if(c->MSS) bands[i].msf = get_bits1(&gb); + if (c->MSS) + bands[i].msf = bitstream_read_bit(&bc); } } /* get scale indexes coding method */ for(i = 0; i <= mb; i++) for(ch = 0; ch < 2; ch++) - if(bands[i].res[ch]) bands[i].scfi[ch] = get_vlc2(&gb, scfi_vlc.table, MPC7_SCFI_BITS, 1); + if (bands[i].res[ch]) + bands[i].scfi[ch] = bitstream_read_vlc(&bc, scfi_vlc.table, MPC7_SCFI_BITS, 1); /* get scale indexes */ for(i = 0; i <= mb; i++){ for(ch = 0; ch < 2; ch++){ if(bands[i].res[ch]){ bands[i].scf_idx[ch][2] = c->oldDSCF[ch][i]; - bands[i].scf_idx[ch][0] = get_scale_idx(&gb, bands[i].scf_idx[ch][2]); + bands[i].scf_idx[ch][0] = get_scale_idx(&bc, bands[i].scf_idx[ch][2]); switch(bands[i].scfi[ch]){ case 0: - bands[i].scf_idx[ch][1] = get_scale_idx(&gb, bands[i].scf_idx[ch][0]); - bands[i].scf_idx[ch][2] = get_scale_idx(&gb, bands[i].scf_idx[ch][1]); + bands[i].scf_idx[ch][1] = get_scale_idx(&bc, bands[i].scf_idx[ch][0]); + bands[i].scf_idx[ch][2] = get_scale_idx(&bc, bands[i].scf_idx[ch][1]); break; case 1: - bands[i].scf_idx[ch][1] = get_scale_idx(&gb, bands[i].scf_idx[ch][0]); + bands[i].scf_idx[ch][1] = get_scale_idx(&bc, bands[i].scf_idx[ch][0]); bands[i].scf_idx[ch][2] = bands[i].scf_idx[ch][1]; break; case 2: bands[i].scf_idx[ch][1] = bands[i].scf_idx[ch][0]; - bands[i].scf_idx[ch][2] = get_scale_idx(&gb, bands[i].scf_idx[ch][1]); + bands[i].scf_idx[ch][2] = get_scale_idx(&bc, bands[i].scf_idx[ch][1]); break; case 3: bands[i].scf_idx[ch][2] = bands[i].scf_idx[ch][1] = bands[i].scf_idx[ch][0]; @@ -290,11 +295,11 @@ static int mpc7_decode_frame(AVCodecContext * avctx, void *data, off = 0; for(i = 0; i < BANDS; i++, off += SAMPLES_PER_BAND) for(ch = 0; ch < 2; ch++) - idx_to_quant(c, &gb, bands[i].res[ch], c->Q[ch] + off); + idx_to_quant(c, &bc, bands[i].res[ch], c->Q[ch] + off); ff_mpc_dequantize_and_synth(c, mb, (int16_t **)frame->extended_data, 2); - bits_used = get_bits_count(&gb); + bits_used = bitstream_tell(&bc); bits_avail = buf_size * 8; if (!last_frame && ((bits_avail < bits_used) || (bits_used + 32 <= bits_avail))) { av_log(avctx, AV_LOG_ERROR, "Error decoding frame: used %i of %i bits\n", bits_used, bits_avail); diff --git a/libavcodec/mpc8.c b/libavcodec/mpc8.c index 84dbb61f7d..cf621afb12 100644 --- a/libavcodec/mpc8.c +++ b/libavcodec/mpc8.c @@ -27,8 +27,9 @@ #include "libavutil/channel_layout.h" #include "libavutil/lfg.h" + #include "avcodec.h" -#include "get_bits.h" +#include "bitstream.h" #include "internal.h" #include "mpegaudiodsp.h" @@ -42,22 +43,22 @@ static VLC q1_vlc, q2_vlc[2], q3_vlc[2], quant_vlc[4][2], q9up_vlc; static const int q3_offsets[2] = { MPC8_Q3_OFFSET, MPC8_Q4_OFFSET }; static const int quant_offsets[6] = { MPC8_Q5_OFFSET, MPC8_Q6_OFFSET, MPC8_Q7_OFFSET, MPC8_Q8_OFFSET }; -static inline int mpc8_dec_base(GetBitContext *gb, int k, int n) +static inline int mpc8_dec_base(BitstreamContext *bc, int k, int n) { int len = mpc8_cnk_len[k-1][n-1] - 1; - int code = len ? get_bits_long(gb, len) : 0; + int code = len ? bitstream_read(bc, len) : 0; if (code >= mpc8_cnk_lost[k-1][n-1]) - code = ((code << 1) | get_bits1(gb)) - mpc8_cnk_lost[k-1][n-1]; + code = ((code << 1) | bitstream_read_bit(bc)) - mpc8_cnk_lost[k - 1][n - 1]; return code; } -static inline int mpc8_dec_enum(GetBitContext *gb, int k, int n) +static inline int mpc8_dec_enum(BitstreamContext *bc, int k, int n) { int bits = 0; const uint32_t * C = mpc8_cnk[k-1]; - int code = mpc8_dec_base(gb, k, n); + int code = mpc8_dec_base(bc, k, n); do { n--; @@ -72,18 +73,18 @@ static inline int mpc8_dec_enum(GetBitContext *gb, int k, int n) return bits; } -static inline int mpc8_get_mod_golomb(GetBitContext *gb, int m) +static inline int mpc8_get_mod_golomb(BitstreamContext *bc, int m) { if(mpc8_cnk_len[0][m] < 1) return 0; - return mpc8_dec_base(gb, 1, m+1); + return mpc8_dec_base(bc, 1, m + 1); } -static int mpc8_get_mask(GetBitContext *gb, int size, int t) +static int mpc8_get_mask(BitstreamContext *bc, int size, int t) { int mask = 0; if(t && t != size) - mask = mpc8_dec_enum(gb, FFMIN(t, size - t), size); + mask = mpc8_dec_enum(bc, FFMIN(t, size - t), size); if((t << 1) > size) mask = ~mask; return mask; @@ -97,7 +98,7 @@ static av_cold int mpc8_decode_init(AVCodecContext * avctx) { int i; MPCContext *c = avctx->priv_data; - GetBitContext gb; + BitstreamContext bc; static int vlc_initialized = 0; int channels; @@ -122,17 +123,17 @@ static av_cold int mpc8_decode_init(AVCodecContext * avctx) ff_mpc_init(); - init_get_bits(&gb, avctx->extradata, 16); + bitstream_init(&bc, avctx->extradata, 16); - skip_bits(&gb, 3);//sample rate - c->maxbands = get_bits(&gb, 5) + 1; - channels = get_bits(&gb, 4) + 1; + bitstream_skip(&bc, 3); // sample rate + c->maxbands = bitstream_read(&bc, 5) + 1; + channels = bitstream_read(&bc, 4) + 1; if (channels > 2) { avpriv_request_sample(avctx, "Multichannel MPC SV8"); return AVERROR_PATCHWELCOME; } - c->MSS = get_bits1(&gb); - c->frames = 1 << (get_bits(&gb, 3) * 2); + c->MSS = bitstream_read_bit(&bc); + c->frames = 1 << (bitstream_read(&bc, 3) * 2); avctx->sample_fmt = AV_SAMPLE_FMT_S16P; avctx->channel_layout = (avctx->channels==2) ? AV_CH_LAYOUT_STEREO : AV_CH_LAYOUT_MONO; @@ -238,7 +239,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, const uint8_t *buf = avpkt->data; int buf_size = avpkt->size; MPCContext *c = avctx->priv_data; - GetBitContext gb2, *gb = &gb2; + BitstreamContext bc2, *bc = &bc2; int i, j, k, ch, cnt, res, t; Band *bands = c->bands; int off; @@ -258,13 +259,13 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, memset(c->Q, 0, sizeof(c->Q)); c->last_bits_used = 0; } - init_get_bits(gb, buf, buf_size * 8); - skip_bits(gb, c->last_bits_used & 7); + bitstream_init(bc, buf, buf_size * 8); + bitstream_skip(bc, c->last_bits_used & 7); if(keyframe) - maxband = mpc8_get_mod_golomb(gb, c->maxbands + 1); + maxband = mpc8_get_mod_golomb(bc, c->maxbands + 1); else{ - maxband = c->last_max_band + get_vlc2(gb, band_vlc.table, MPC8_BANDS_BITS, 2); + maxband = c->last_max_band + bitstream_read_vlc(bc, band_vlc.table, MPC8_BANDS_BITS, 2); if(maxband > 32) maxband -= 33; } if(maxband > c->maxbands + 1) @@ -276,7 +277,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, last[0] = last[1] = 0; for(i = maxband - 1; i >= 0; i--){ for(ch = 0; ch < 2; ch++){ - last[ch] = get_vlc2(gb, res_vlc[last[ch] > 2].table, MPC8_RES_BITS, 2) + last[ch]; + last[ch] = bitstream_read_vlc(bc, res_vlc[last[ch] > 2].table, MPC8_RES_BITS, 2) + last[ch]; if(last[ch] > 15) last[ch] -= 17; bands[i].res[ch] = last[ch]; } @@ -288,8 +289,8 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, for(i = 0; i < maxband; i++) if(bands[i].res[0] || bands[i].res[1]) cnt++; - t = mpc8_get_mod_golomb(gb, cnt); - mask = mpc8_get_mask(gb, cnt, t); + t = mpc8_get_mod_golomb(bc, cnt); + mask = mpc8_get_mask(bc, cnt, t); for(i = maxband - 1; i >= 0; i--) if(bands[i].res[0] || bands[i].res[1]){ bands[i].msf = mask & 1; @@ -309,7 +310,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, if(bands[i].res[0] || bands[i].res[1]){ cnt = !!bands[i].res[0] + !!bands[i].res[1] - 1; if(cnt >= 0){ - t = get_vlc2(gb, scfi_vlc[cnt].table, scfi_vlc[cnt].bits, 1); + t = bitstream_read_vlc(bc, scfi_vlc[cnt].table, scfi_vlc[cnt].bits, 1); if(bands[i].res[0]) bands[i].scfi[0] = t >> (2 * cnt); if(bands[i].res[1]) bands[i].scfi[1] = t & 3; } @@ -321,21 +322,21 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, if(!bands[i].res[ch]) continue; if(c->oldDSCF[ch][i]){ - bands[i].scf_idx[ch][0] = get_bits(gb, 7) - 6; + bands[i].scf_idx[ch][0] = bitstream_read(bc, 7) - 6; c->oldDSCF[ch][i] = 0; }else{ - t = get_vlc2(gb, dscf_vlc[1].table, MPC8_DSCF1_BITS, 2); + t = bitstream_read_vlc(bc, dscf_vlc[1].table, MPC8_DSCF1_BITS, 2); if(t == 64) - t += get_bits(gb, 6); + t += bitstream_read(bc, 6); bands[i].scf_idx[ch][0] = ((bands[i].scf_idx[ch][2] + t - 25) & 0x7F) - 6; } for(j = 0; j < 2; j++){ if((bands[i].scfi[ch] << j) & 2) bands[i].scf_idx[ch][j + 1] = bands[i].scf_idx[ch][j]; else{ - t = get_vlc2(gb, dscf_vlc[0].table, MPC8_DSCF0_BITS, 2); + t = bitstream_read_vlc(bc, dscf_vlc[0].table, MPC8_DSCF0_BITS, 2); if(t == 31) - t = 64 + get_bits(gb, 6); + t = 64 + bitstream_read(bc, 6); bands[i].scf_idx[ch][j + 1] = ((bands[i].scf_idx[ch][j] + t - 25) & 0x7F) - 6; } } @@ -354,16 +355,16 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, break; case 1: for(j = 0; j < SAMPLES_PER_BAND; j += SAMPLES_PER_BAND / 2){ - cnt = get_vlc2(gb, q1_vlc.table, MPC8_Q1_BITS, 2); - t = mpc8_get_mask(gb, 18, cnt); + cnt = bitstream_read_vlc(bc, q1_vlc.table, MPC8_Q1_BITS, 2); + t = mpc8_get_mask(bc, 18, cnt); for(k = 0; k < SAMPLES_PER_BAND / 2; k++, t <<= 1) - c->Q[ch][off + j + k] = (t & 0x20000) ? (get_bits1(gb) << 1) - 1 : 0; + c->Q[ch][off + j + k] = (t & 0x20000) ? (bitstream_read_bit(bc) << 1) - 1 : 0; } break; case 2: cnt = 6;//2*mpc8_thres[res] for(j = 0; j < SAMPLES_PER_BAND; j += 3){ - t = get_vlc2(gb, q2_vlc[cnt > 3].table, MPC8_Q2_BITS, 2); + t = bitstream_read_vlc(bc, q2_vlc[cnt > 3].table, MPC8_Q2_BITS, 2); c->Q[ch][off + j + 0] = mpc8_idx50[t]; c->Q[ch][off + j + 1] = mpc8_idx51[t]; c->Q[ch][off + j + 2] = mpc8_idx52[t]; @@ -373,7 +374,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, case 3: case 4: for(j = 0; j < SAMPLES_PER_BAND; j += 2){ - t = get_vlc2(gb, q3_vlc[res - 3].table, MPC8_Q3_BITS, 2) + q3_offsets[res - 3]; + t = bitstream_read_vlc(bc, q3_vlc[res - 3].table, MPC8_Q3_BITS, 2) + q3_offsets[res - 3]; c->Q[ch][off + j + 1] = t >> 4; c->Q[ch][off + j + 0] = (t & 8) ? (t & 0xF) - 16 : (t & 0xF); } @@ -384,17 +385,17 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, case 8: cnt = 2 * mpc8_thres[res]; for(j = 0; j < SAMPLES_PER_BAND; j++){ - t = get_vlc2(gb, quant_vlc[res - 5][cnt > mpc8_thres[res]].table, quant_vlc[res - 5][cnt > mpc8_thres[res]].bits, 2) + quant_offsets[res - 5]; + t = bitstream_read_vlc(bc, quant_vlc[res - 5][cnt > mpc8_thres[res]].table, quant_vlc[res - 5][cnt > mpc8_thres[res]].bits, 2) + quant_offsets[res - 5]; c->Q[ch][off + j] = t; cnt = (cnt >> 1) + FFABS(c->Q[ch][off + j]); } break; default: for(j = 0; j < SAMPLES_PER_BAND; j++){ - c->Q[ch][off + j] = get_vlc2(gb, q9up_vlc.table, MPC8_Q9UP_BITS, 2); + c->Q[ch][off + j] = bitstream_read_vlc(bc, q9up_vlc.table, MPC8_Q9UP_BITS, 2); if(res != 9){ c->Q[ch][off + j] <<= res - 9; - c->Q[ch][off + j] |= get_bits(gb, res - 9); + c->Q[ch][off + j] |= bitstream_read(bc, res - 9); } c->Q[ch][off + j] -= (1 << (res - 2)) - 1; } @@ -408,8 +409,8 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, c->cur_frame++; - c->last_bits_used = get_bits_count(gb); - if(get_bits_left(gb) < 8) // we have only padding left + c->last_bits_used = bitstream_tell(bc); + if (bitstream_bits_left(bc) < 8) // we have only padding left c->last_bits_used = buf_size << 3; if(c->cur_frame >= c->frames) c->cur_frame = 0; diff --git a/libavformat/mpc8.c b/libavformat/mpc8.c index 132e3cd907..c4027e5d88 100644 --- a/libavformat/mpc8.c +++ b/libavformat/mpc8.c @@ -19,8 +19,8 @@ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ -#include "libavcodec/get_bits.h" -#include "libavcodec/unary_legacy.h" +#include "libavcodec/bitstream.h" +#include "libavcodec/unary.h" #include "apetag.h" #include "avformat.h" @@ -107,17 +107,17 @@ static int mpc8_probe(AVProbeData *p) return 0; } -static inline int64_t gb_get_v(GetBitContext *gb) +static inline int64_t gb_get_v(BitstreamContext *bc) { int64_t v = 0; int bits = 0; - while(get_bits1(gb) && bits < 64-7){ + while (bitstream_read_bit(bc) && bits < 64 - 7) { v <<= 7; - v |= get_bits(gb, 7); + v |= bitstream_read(bc, 7); bits += 7; } v <<= 7; - v |= get_bits(gb, 7); + v |= bitstream_read(bc, 7); return v; } @@ -138,7 +138,7 @@ static void mpc8_parse_seektable(AVFormatContext *s, int64_t off) int64_t size, pos, ppos[2]; uint8_t *buf; int i, t, seekd; - GetBitContext gb; + BitstreamContext bc; if (s->nb_streams == 0) { av_log(s, AV_LOG_ERROR, "No stream added before parsing seek table\n"); @@ -158,21 +158,21 @@ static void mpc8_parse_seektable(AVFormatContext *s, int64_t off) if(!(buf = av_malloc(size + AV_INPUT_BUFFER_PADDING_SIZE))) return; avio_read(s->pb, buf, size); - init_get_bits(&gb, buf, size * 8); - size = gb_get_v(&gb); + bitstream_init8(&bc, buf, size); + size = gb_get_v(&bc); if(size > UINT_MAX/4 || size > c->samples/1152){ av_log(s, AV_LOG_ERROR, "Seek table is too big\n"); return; } - seekd = get_bits(&gb, 4); + seekd = bitstream_read(&bc, 4); for(i = 0; i < 2; i++){ - pos = gb_get_v(&gb) + c->header_pos; + pos = gb_get_v(&bc) + c->header_pos; ppos[1 - i] = pos; av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME); } for(; i < size; i++){ - t = get_unary(&gb, 1, 33) << 12; - t += get_bits(&gb, 12); + t = get_unary(&bc, 1, 33) << 12; + t += bitstream_read(&bc, 12); if(t & 1) t = -(t & ~1); pos = (t >> 1) + ppos[0]*2 - ppos[1];