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