/libavcodec/mqcenc.c

  1/*
  2 * MQ-coder encoder
  3 * Copyright (c) 2007 Kamil Nowosad
  4 *
  5 * This file is part of FFmpeg.
  6 *
  7 * FFmpeg is free software; you can redistribute it and/or
  8 * modify it under the terms of the GNU Lesser General Public
  9 * License as published by the Free Software Foundation; either
 10 * version 2.1 of the License, or (at your option) any later version.
 11 *
 12 * FFmpeg is distributed in the hope that it will be useful,
 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 15 * Lesser General Public License for more details.
 16 *
 17 * You should have received a copy of the GNU Lesser General Public
 18 * License along with FFmpeg; if not, write to the Free Software
 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 20 */
 21
 22/**
 23 * MQ-coder encoder
 24 * @file
 25 * @author Kamil Nowosad
 26 */
 27
 28#include "libavutil/avassert.h"
 29#include "mqc.h"
 30
 31static void byteout(MqcState *mqc)
 32{
 33retry:
 34    if (*mqc->bp == 0xff){
 35        mqc->bp++;
 36        *mqc->bp = mqc->c >> 20;
 37        mqc->c &= 0xfffff;
 38        mqc->ct = 7;
 39    } else if ((mqc->c & 0x8000000)){
 40        (*mqc->bp)++;
 41        mqc->c &= 0x7ffffff;
 42        goto retry;
 43    } else{
 44        mqc->bp++;
 45        *mqc->bp = mqc->c >> 19;
 46        mqc->c &= 0x7ffff;
 47        mqc->ct = 8;
 48    }
 49}
 50
 51static void renorme(MqcState *mqc)
 52{
 53    do{
 54        mqc->a += mqc->a;
 55        mqc->c += mqc->c;
 56        if (!--mqc->ct)
 57            byteout(mqc);
 58    } while (!(mqc->a & 0x8000));
 59}
 60
 61static void setbits(MqcState *mqc)
 62{
 63    int tmp = mqc->c + mqc->a;
 64    mqc->c |= 0xffff;
 65    if (mqc->c >= tmp)
 66        mqc->c -= 0x8000;
 67}
 68
 69void ff_mqc_initenc(MqcState *mqc, uint8_t *bp)
 70{
 71    ff_mqc_init_contexts(mqc);
 72    mqc->a = 0x8000;
 73    mqc->c = 0;
 74    mqc->bp = bp-1;
 75    mqc->bpstart = bp;
 76    mqc->ct = 12 + (*mqc->bp == 0xff);
 77}
 78
 79void ff_mqc_encode(MqcState *mqc, uint8_t *cxstate, int d)
 80{
 81    int qe;
 82
 83    qe = ff_mqc_qe[*cxstate];
 84    mqc->a -= qe;
 85    if ((*cxstate & 1) == d){
 86        if (!(mqc->a & 0x8000)){
 87            if (mqc->a < qe)
 88                mqc->a = qe;
 89            else
 90                mqc->c += qe;
 91            *cxstate = ff_mqc_nmps[*cxstate];
 92            renorme(mqc);
 93        } else
 94            mqc->c += qe;
 95    } else{
 96        if (mqc->a < qe)
 97            mqc->c += qe;
 98        else
 99            mqc->a = qe;
100        *cxstate = ff_mqc_nlps[*cxstate];
101        renorme(mqc);
102    }
103}
104
105int ff_mqc_length(MqcState *mqc)
106{
107    return mqc->bp - mqc->bpstart;
108}
109
110int ff_mqc_flush(MqcState *mqc)
111{
112    setbits(mqc);
113    mqc->c = mqc->c << mqc->ct;
114    byteout(mqc);
115    mqc->c = mqc->c << mqc->ct;
116    byteout(mqc);
117    if (*mqc->bp != 0xff)
118        mqc->bp++;
119    return mqc->bp - mqc->bpstart;
120}
121
122int ff_mqc_flush_to(MqcState *mqc, uint8_t *dst, int *dst_len)
123{
124    MqcState mqc2 = *mqc;
125    mqc2.bpstart=
126    mqc2.bp = dst;
127    *mqc2.bp = *mqc->bp;
128    ff_mqc_flush(&mqc2);
129    *dst_len = mqc2.bp - dst;
130    if (mqc->bp < mqc->bpstart) {
131        av_assert1(mqc->bpstart - mqc->bp == 1);
132        av_assert1(*dst_len > 0);
133        av_assert1(mqc->bp[0] == 0 && dst[0] == 0);
134        (*dst_len) --;
135        memmove(dst, dst+1, *dst_len);
136        return mqc->bp - mqc->bpstart + 1 + *dst_len;
137    }
138    return mqc->bp - mqc->bpstart + *dst_len;
139}