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
|
#include "bitstream.h"
#include <stdlib.h>
#include <string.h>
void bitstream_reader_init(struct bitstream_reader *r, uint8_t *data,
size_t len)
{
memset(r, 0, sizeof(struct bitstream_reader));
r->buf = data;
r->subPos = 0x80;
r->len = len;
}
uint8_t bitstream_reader_read_bit(struct bitstream_reader *r)
{
if (r->pos >= r->len)
return 0;
uint8_t bit = (*(r->buf + r->pos) & r->subPos) == r->subPos ? 1 : 0;
r->subPos >>= 0x1;
if (r->subPos == 0) {
r->subPos = 0x80;
r->pos++;
}
return bit;
}
uint8_t bitstream_reader_read_bits(struct bitstream_reader *r, int bits)
{
uint8_t res = 0;
for (int i = 1; i <= bits; i++) {
res <<= 1;
res |= bitstream_reader_read_bit(r);
}
return res;
}
uint8_t bitstream_reader_r8(struct bitstream_reader *r)
{
return bitstream_reader_read_bits(r, 8);
}
uint16_t bitstream_reader_r16(struct bitstream_reader *r)
{
uint8_t b = bitstream_reader_read_bits(r, 8);
return ((uint16_t)b << 8) | bitstream_reader_read_bits(r, 8);
}
|
