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|---|---|---|---|
| 1 | /* | ||
| 2 | * MQ-coder decoder | ||
| 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 decoder | ||
| 24 | * @file | ||
| 25 | * @author Kamil Nowosad | ||
| 26 | */ | ||
| 27 | |||
| 28 | #include "mqc.h" | ||
| 29 | |||
| 30 | 83189369 | static void bytein(MqcState *mqc) | |
| 31 | { | ||
| 32 |
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83189369 | if (*mqc->bp == 0xff) { |
| 33 |
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1207192 | if (*(mqc->bp + 1) > 0x8f) |
| 34 | 845751 | mqc->c++; | |
| 35 | else { | ||
| 36 | 361441 | mqc->bp++; | |
| 37 | 361441 | mqc->c += 2 + 0xfe00 - (*mqc->bp << 9); | |
| 38 | } | ||
| 39 | } else { | ||
| 40 | 81982177 | mqc->bp++; | |
| 41 | 81982177 | mqc->c += 1 + 0xff00 - (*mqc->bp << 8); | |
| 42 | } | ||
| 43 | 83189369 | } | |
| 44 | |||
| 45 | 493782045 | static int exchange(MqcState *mqc, uint8_t *cxstate, int lps) | |
| 46 | { | ||
| 47 | int d; | ||
| 48 |
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493782045 | if ((mqc->a < ff_mqc_qe[*cxstate]) ^ (!lps)) { |
| 49 |
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244249122 | if (lps) |
| 50 | 59928636 | mqc->a = ff_mqc_qe[*cxstate]; | |
| 51 | 244249122 | d = *cxstate & 1; | |
| 52 | 244249122 | *cxstate = ff_mqc_nmps[*cxstate]; | |
| 53 | } else { | ||
| 54 |
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249532923 | if (lps) |
| 55 | 196746009 | mqc->a = ff_mqc_qe[*cxstate]; | |
| 56 | 249532923 | d = 1 - (*cxstate & 1); | |
| 57 | 249532923 | *cxstate = ff_mqc_nlps[*cxstate]; | |
| 58 | } | ||
| 59 | // do RENORMD: see ISO/IEC 15444-1:2002 §C.3.3 | ||
| 60 | do { | ||
| 61 |
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656495505 | if (!(mqc->c & 0xff)) { |
| 62 | 82374248 | mqc->c -= 0x100; | |
| 63 | 82374248 | bytein(mqc); | |
| 64 | } | ||
| 65 | 656495505 | mqc->a += mqc->a; | |
| 66 | 656495505 | mqc->c += mqc->c; | |
| 67 |
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656495505 | } while (!(mqc->a & 0x8000)); |
| 68 | 493782045 | return d; | |
| 69 | } | ||
| 70 | |||
| 71 | 815121 | void ff_mqc_initdec(MqcState *mqc, uint8_t *bp, int raw, int reset) | |
| 72 | { | ||
| 73 | 815121 | mqc->raw = raw; | |
| 74 |
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815121 | if (reset) |
| 75 | 811260 | ff_mqc_init_contexts(mqc); | |
| 76 | 815121 | mqc->bp = bp; | |
| 77 | 815121 | mqc->c = (*mqc->bp ^ 0xff) << 16; | |
| 78 | 815121 | bytein(mqc); | |
| 79 | 815121 | mqc->c = mqc->c << 7; | |
| 80 | 815121 | mqc->a = 0x8000; | |
| 81 | 815121 | } | |
| 82 | |||
| 83 | ✗ | static int mqc_decode_bypass(MqcState *mqc) { | |
| 84 | ✗ | int bit = !(mqc->c & 0x40000000); | |
| 85 | ✗ | if (!(mqc->c & 0xff)) { | |
| 86 | ✗ | mqc->c -= 0x100; | |
| 87 | ✗ | bytein(mqc); | |
| 88 | } | ||
| 89 | ✗ | mqc->c += mqc->c; | |
| 90 | ✗ | return bit; | |
| 91 | } | ||
| 92 | |||
| 93 | 882905814 | int ff_mqc_decode(MqcState *mqc, uint8_t *cxstate) | |
| 94 | { | ||
| 95 |
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882905814 | if (mqc->raw) |
| 96 | ✗ | return mqc_decode_bypass(mqc); | |
| 97 | 882905814 | mqc->a -= ff_mqc_qe[*cxstate]; | |
| 98 |
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882905814 | if ((mqc->c >> 16) < mqc->a) { |
| 99 |
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626231169 | if (mqc->a & 0x8000) |
| 100 | 389123769 | return *cxstate & 1; | |
| 101 | else | ||
| 102 | 237107400 | return exchange(mqc, cxstate, 0); | |
| 103 | } else { | ||
| 104 | 256674645 | mqc->c -= mqc->a << 16; | |
| 105 | 256674645 | return exchange(mqc, cxstate, 1); | |
| 106 | } | ||
| 107 | } | ||
| 108 |