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/* |
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* Discworld II BMV video decoder |
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* Copyright (c) 2011 Konstantin Shishkov |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "libavutil/avassert.h" |
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#include "libavutil/common.h" |
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#include "avcodec.h" |
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#include "bytestream.h" |
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#include "internal.h" |
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enum BMVFlags{ |
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BMV_NOP = 0, |
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BMV_END, |
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BMV_DELTA, |
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BMV_INTRA, |
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BMV_SCROLL = 0x04, |
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BMV_PALETTE = 0x08, |
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BMV_COMMAND = 0x10, |
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BMV_AUDIO = 0x20, |
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BMV_EXT = 0x40, |
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BMV_PRINT = 0x80 |
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}; |
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#define SCREEN_WIDE 640 |
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#define SCREEN_HIGH 429 |
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typedef struct BMVDecContext { |
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AVCodecContext *avctx; |
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uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)]; |
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uint32_t pal[256]; |
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const uint8_t *stream; |
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} BMVDecContext; |
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#define NEXT_BYTE(v) (v) = forward ? (v) + 1 : (v) - 1; |
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static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off) |
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{ |
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unsigned val, saved_val = 0; |
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int tmplen = src_len; |
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const uint8_t *src, *source_end = source + src_len; |
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uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH; |
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uint8_t *dst, *dst_end; |
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int len, mask; |
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✓✓✓✗
|
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int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0); |
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int read_two_nibbles, flag; |
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int advance_mode; |
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int mode = 0; |
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int i; |
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✗✓ |
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if (src_len <= 0) |
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return AVERROR_INVALIDDATA; |
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✓✗ |
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if (forward) { |
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src = source; |
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dst = frame; |
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dst_end = frame_end; |
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} else { |
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src = source + src_len - 1; |
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dst = frame_end - 1; |
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dst_end = frame - 1; |
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} |
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for (;;) { |
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int shift = 0; |
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flag = 0; |
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/* The mode/len decoding is a bit strange: |
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* values are coded as variable-length codes with nibble units, |
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* code end is signalled by two top bits in the nibble being nonzero. |
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* And since data is bytepacked and we read two nibbles at a time, |
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* we may get a nibble belonging to the next code. |
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* Hence this convoluted loop. |
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*/ |
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✓✓✓✓
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if (!mode || (tmplen == 4)) { |
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✓✗✗✓
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if (src < source || src >= source_end) |
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return AVERROR_INVALIDDATA; |
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val = *src; |
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read_two_nibbles = 1; |
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} else { |
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val = saved_val; |
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read_two_nibbles = 0; |
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} |
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✓✓ |
783673 |
if (!(val & 0xC)) { |
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for (;;) { |
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✗✓ |
73874 |
if(shift>22) |
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return -1; |
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✓✓ |
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if (!read_two_nibbles) { |
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✓✗✗✓
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if (src < source || src >= source_end) |
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return AVERROR_INVALIDDATA; |
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shift += 2; |
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val |= (unsigned)*src << shift; |
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✓✓ |
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if (*src & 0xC) |
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break; |
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} |
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// two upper bits of the nibble is zero, |
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// so shift top nibble value down into their place |
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read_two_nibbles = 0; |
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shift += 2; |
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mask = (1 << shift) - 1; |
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val = ((val >> 2) & ~mask) | (val & mask); |
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✓✗ |
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NEXT_BYTE(src); |
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✓✓ |
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if ((val & (0xC << shift))) { |
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flag = 1; |
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break; |
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} |
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} |
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✓✓ |
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} else if (mode) { |
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flag = tmplen != 4; |
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} |
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✓✓ |
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if (flag) { |
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tmplen = 4; |
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} else { |
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saved_val = val >> (4 + shift); |
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tmplen = 0; |
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val &= (1 << (shift + 4)) - 1; |
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✓✗ |
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NEXT_BYTE(src); |
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} |
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advance_mode = val & 1; |
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len = (val >> 1) - 1; |
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✗✓ |
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av_assert0(len>0); |
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mode += 1 + advance_mode; |
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✓✓ |
783673 |
if (mode >= 4) |
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mode -= 3; |
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✓✗✓✗ ✗✓ |
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if (len <= 0 || FFABS(dst_end - dst) < len) |
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return AVERROR_INVALIDDATA; |
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✓✓✓✗
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switch (mode) { |
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case 1: |
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✓✗ |
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if (forward) { |
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✓✗ |
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if (dst - frame + SCREEN_WIDE < frame_off || |
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✓✗ |
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dst - frame + SCREEN_WIDE + frame_off < 0 || |
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✓✗ |
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frame_end - dst < frame_off + len || |
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✗✓ |
207200 |
frame_end - dst < len) |
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return AVERROR_INVALIDDATA; |
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✓✓ |
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for (i = 0; i < len; i++) |
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dst[i] = dst[frame_off + i]; |
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dst += len; |
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} else { |
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dst -= len; |
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if (dst - frame + SCREEN_WIDE < frame_off || |
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dst - frame + SCREEN_WIDE + frame_off < 0 || |
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frame_end - dst < frame_off + len || |
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frame_end - dst < len) |
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return AVERROR_INVALIDDATA; |
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for (i = len - 1; i >= 0; i--) |
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dst[i] = dst[frame_off + i]; |
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} |
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break; |
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case 2: |
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✓✗ |
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if (forward) { |
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✗✓ |
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if (source + src_len - src < len) |
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return AVERROR_INVALIDDATA; |
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memcpy(dst, src, len); |
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dst += len; |
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src += len; |
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} else { |
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if (src - source < len) |
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return AVERROR_INVALIDDATA; |
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dst -= len; |
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src -= len; |
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memcpy(dst, src, len); |
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} |
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break; |
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case 3: |
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✓✗ |
263848 |
val = forward ? dst[-1] : dst[1]; |
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✓✗ |
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if (forward) { |
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memset(dst, val, len); |
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dst += len; |
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} else { |
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dst -= len; |
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memset(dst, val, len); |
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} |
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263848 |
break; |
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} |
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✓✓ |
783673 |
if (dst == dst_end) |
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return 0; |
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} |
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} |
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static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, |
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AVPacket *pkt) |
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{ |
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BMVDecContext * const c = avctx->priv_data; |
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AVFrame *frame = data; |
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int type, scr_off; |
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int i, ret; |
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uint8_t *srcptr, *outptr; |
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c->stream = pkt->data; |
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type = bytestream_get_byte(&c->stream); |
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✓✗ |
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if (type & BMV_AUDIO) { |
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int blobs = bytestream_get_byte(&c->stream); |
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✗✓ |
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if (pkt->size < blobs * 65 + 2) { |
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av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n"); |
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return AVERROR_INVALIDDATA; |
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} |
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c->stream += blobs * 65; |
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} |
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✗✓ |
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if (type & BMV_COMMAND) { |
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int command_size = (type & BMV_PRINT) ? 8 : 10; |
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if (c->stream - pkt->data + command_size > pkt->size) { |
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av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n"); |
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return AVERROR_INVALIDDATA; |
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} |
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c->stream += command_size; |
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} |
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✓✓ |
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if (type & BMV_PALETTE) { |
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✗✓ |
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if (c->stream - pkt->data > pkt->size - 768) { |
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av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n"); |
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return AVERROR_INVALIDDATA; |
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} |
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✓✓ |
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for (i = 0; i < 256; i++) |
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c->pal[i] = 0xFFU << 24 | bytestream_get_be24(&c->stream); |
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} |
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✗✓ |
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if (type & BMV_SCROLL) { |
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if (c->stream - pkt->data > pkt->size - 2) { |
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av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n"); |
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return AVERROR_INVALIDDATA; |
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} |
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scr_off = (int16_t)bytestream_get_le16(&c->stream); |
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✓✓ |
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} else if ((type & BMV_INTRA) == BMV_INTRA) { |
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scr_off = -640; |
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} else { |
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scr_off = 0; |
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} |
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✗✓ |
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if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) |
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return ret; |
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✗✓ |
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if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) { |
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av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n"); |
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return AVERROR_INVALIDDATA; |
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} |
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memcpy(frame->data[1], c->pal, AVPALETTE_SIZE); |
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frame->palette_has_changed = type & BMV_PALETTE; |
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outptr = frame->data[0]; |
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srcptr = c->frame; |
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✓✓ |
9030 |
for (i = 0; i < avctx->height; i++) { |
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memcpy(outptr, srcptr, avctx->width); |
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|
9009 |
srcptr += avctx->width; |
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|
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outptr += frame->linesize[0]; |
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} |
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*got_frame = 1; |
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/* always report that the buffer was completely consumed */ |
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return pkt->size; |
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} |
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|
3 |
static av_cold int decode_init(AVCodecContext *avctx) |
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{ |
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BMVDecContext * const c = avctx->priv_data; |
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|
3 |
c->avctx = avctx; |
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avctx->pix_fmt = AV_PIX_FMT_PAL8; |
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✓✗✗✓
|
3 |
if (avctx->width != SCREEN_WIDE || avctx->height != SCREEN_HIGH) { |
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av_log(avctx, AV_LOG_ERROR, "Invalid dimension %dx%d\n", avctx->width, avctx->height); |
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return AVERROR_INVALIDDATA; |
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} |
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|
3 |
c->frame = c->frame_base + 640; |
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|
3 |
return 0; |
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} |
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AVCodec ff_bmv_video_decoder = { |
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.name = "bmv_video", |
290 |
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.long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV video"), |
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.type = AVMEDIA_TYPE_VIDEO, |
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.id = AV_CODEC_ID_BMV_VIDEO, |
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.priv_data_size = sizeof(BMVDecContext), |
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.init = decode_init, |
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.decode = decode_frame, |
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.capabilities = AV_CODEC_CAP_DR1, |
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.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE, |
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}; |