Libav
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 Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
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  if (buf_size == 0)
49  return 0;
50 
51  if (!bpc->pc.frame_start_found) {
52  for (; i < buf_size; i++) {
53  state = (state << 8) | buf[i];
54  if ((state >> 48) == (('B' << 8) | 'M')) {
55  bpc->fsize = av_bswap32(state >> 16);
56  bpc->pc.frame_start_found = 1;
57  if (bpc->fsize > buf_size - i + 7)
58  bpc->remaining_size = bpc->fsize - buf_size + i - 7;
59  else
60  next = bpc->fsize + i - 7;
61  break;
62  }
63  }
64  bpc->pc.state64 = state;
65  } else {
66  if (bpc->remaining_size) {
67  i = FFMIN(bpc->remaining_size, buf_size);
68  bpc->remaining_size -= i;
69  if (bpc->remaining_size)
70  goto flush;
71  next = i;
72  }
73  }
74 
75 flush:
76  if (ff_combine_frame(&bpc->pc, next, &buf, &buf_size) < 0)
77  return buf_size;
78 
79  bpc->pc.frame_start_found = 0;
80 
81  *poutbuf = buf;
82  *poutbuf_size = buf_size;
83  return next;
84 }
85 
88  .priv_data_size = sizeof(BMPParseContext),
89  .parser_parse = bmp_parse,
90  .parser_close = ff_parse_close,
91 };
uint32_t fsize
Definition: bmp_parser.c:34
AVCodecParser ff_bmp_parser
Definition: bmp_parser.c:86
ParseContext pc
Definition: bmp_parser.c:33
int codec_ids[5]
Definition: avcodec.h:3838
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:217
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:287
#define FFMIN(a, b)
Definition: common.h:57
#define av_bswap32
Definition: bswap.h:33
main external API structure.
Definition: avcodec.h:1050
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
static uint32_t state
Definition: trasher.c:27
common internal and external API header
static av_cold void flush(AVCodecContext *avctx)
Flush (reset) the frame ID after seeking.
Definition: alsdec.c:1797
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