1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
#include "read.h"
/* helper macro to do a read, check error code and number of bytes read, and return from the function if necessary
has to be a macro because of the return */
#define NSAVI_READ(reader, buffer, size, bytes_read) { int ret = reader->Read(buffer, size, &bytes_read); if (ret) return ret; if (bytes_read != size) return READ_EOF; }
int nsavi::read_riff_chunk(nsavi::avi_reader *reader, nsavi::riff_chunk *chunk, uint32_t *out_bytes_read)
{
uint32_t total_bytes_read=0;
uint32_t bytes_read;
NSAVI_READ(reader, chunk, 8, bytes_read); // read id and size
total_bytes_read += bytes_read;
if (chunk->id == 'FFIR' || chunk->id == 'TSIL')
{
if (chunk->size < 4)
return READ_INVALID_DATA;
NSAVI_READ(reader, &chunk->type, 4, bytes_read);
total_bytes_read += bytes_read;
chunk->size -= 4;
}
else
chunk->type = 0;
if (out_bytes_read)
*out_bytes_read = total_bytes_read;
return READ_OK;
}
// we pass riff_chunk instead of size
// to avoid any confusion about who is responsible for adding the padding byte
// (this function is responsible)
int nsavi::skip_chunk(nsavi::avi_reader *reader, const nsavi::riff_chunk *chunk, uint32_t *out_bytes_read)
{
uint32_t chunk_size = chunk->size;
if (chunk_size & 1)
{
chunk_size ++; // odd chunk sizes must be padded by one
if (chunk_size == 0) // check for overflow
return READ_INVALID_DATA;
}
int ret = reader->Skip(chunk_size);
if (ret)
return ret;
if (out_bytes_read)
*out_bytes_read = chunk_size;
return READ_OK;
}
|
