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bmp_parser.c
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1 /*
2  * BMP parser
3  * Copyright (c) 2012 Paul B Mahol
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  * @file
24  * BMP parser
25  */
26 
27 #include "libavutil/bswap.h"
28 #include "libavutil/common.h"
29 
30 #include "parser.h"
31 
32 typedef struct BMPParseContext {
34  uint32_t fsize;
35  uint32_t remaining_size;
37 
39  const uint8_t **poutbuf, int *poutbuf_size,
40  const uint8_t *buf, int buf_size)
41 {
42  BMPParseContext *bpc = s->priv_data;
43  uint64_t state = bpc->pc.state64;
44  int next = END_NOT_FOUND;
45  int i = 0;
46 
47  *poutbuf_size = 0;
48 
49 restart:
50  if (bpc->pc.frame_start_found <= 2+4+4) {
51  for (; i < buf_size; i++) {
52  state = (state << 8) | buf[i];
53  if (bpc->pc.frame_start_found == 0) {
54  if ((state >> 48) == (('B' << 8) | 'M')) {
55  bpc->fsize = av_bswap32(state >> 16);
56  if (bpc->fsize > 17)
57  bpc->pc.frame_start_found = 1;
58  }
59  } else if (bpc->pc.frame_start_found == 2+4+4) {
60 // unsigned hsize = av_bswap32(state>>32);
61  unsigned ihsize = av_bswap32(state);
62  if (ihsize < 12 || ihsize > 200) {
63  bpc->pc.frame_start_found = 0;
64  continue;
65  }
66  bpc->pc.frame_start_found++;
67  bpc->remaining_size = bpc->fsize + i - 17;
68 
69  if (bpc->pc.index + i > 17) {
70  next = i - 17;
71  state = 0;
72  break;
73  } else {
74  bpc->pc.state64 = 0;
75  goto restart;
76  }
77  } else if (bpc->pc.frame_start_found)
78  bpc->pc.frame_start_found++;
79  }
80  bpc->pc.state64 = state;
81  } else {
82  if (bpc->remaining_size) {
83  i = FFMIN(bpc->remaining_size, buf_size);
84  bpc->remaining_size -= i;
85  if (bpc->remaining_size)
86  goto flush;
87 
88  bpc->pc.frame_start_found = 0;
89  goto restart;
90  }
91  }
92 
93 flush:
94  if (ff_combine_frame(&bpc->pc, next, &buf, &buf_size) < 0)
95  return buf_size;
96 
97  if (next != END_NOT_FOUND && next < 0)
98  bpc->pc.frame_start_found = FFMAX(bpc->pc.frame_start_found - i - 1, 0);
99  else
100  bpc->pc.frame_start_found = 0;
101 
102  *poutbuf = buf;
103  *poutbuf_size = buf_size;
104  return next;
105 }
106 
108  .codec_ids = { AV_CODEC_ID_BMP },
109  .priv_data_size = sizeof(BMPParseContext),
110  .parser_parse = bmp_parse,
111  .parser_close = ff_parse_close,
112 };
uint32_t fsize
Definition: bmp_parser.c:34
const char * s
Definition: avisynth_c.h:768
AVCodecParser ff_bmp_parser
Definition: bmp_parser.c:107
ParseContext pc
Definition: bmp_parser.c:33
static void flush(AVCodecContext *avctx)
int codec_ids[5]
Definition: avcodec.h:5150
int frame_start_found
Definition: parser.h:34
uint8_t
uint32_t remaining_size
Definition: bmp_parser.c:35
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
Combine the (truncated) bitstream to a complete frame.
Definition: parser.c:250
#define FFMAX(a, b)
Definition: common.h:94
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:326
#define FFMIN(a, b)
Definition: common.h:96
#define av_bswap32
Definition: bswap.h:33
main external API structure.
Definition: avcodec.h:1676
static struct @246 state
void * buf
Definition: avisynth_c.h:690
uint64_t state64
contains the last 8 bytes in MSB order
Definition: parser.h:37
byte swapping routines
#define END_NOT_FOUND
Definition: parser.h:40
common internal and external API header
int index
Definition: parser.h:30
static int bmp_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: bmp_parser.c:38