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/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#include <assert.h>
#include "config/aom_config.h"
#include "aom_dsp/bitreader_buffer.h"
#include "aom_dsp/recenter.h"
#include "aom_ports/bitops.h"
size_t aom_rb_bytes_read(const struct aom_read_bit_buffer *rb) {
return (rb->bit_offset + 7) >> 3;
}
int aom_rb_read_bit(struct aom_read_bit_buffer *rb) {
const uint32_t off = rb->bit_offset;
const uint32_t p = off >> 3;
const int q = 7 - (int)(off & 0x7);
if (rb->bit_buffer + p < rb->bit_buffer_end) {
const int bit = (rb->bit_buffer[p] >> q) & 1;
rb->bit_offset = off + 1;
return bit;
} else {
if (rb->error_handler) rb->error_handler(rb->error_handler_data);
return 0;
}
}
int aom_rb_read_literal(struct aom_read_bit_buffer *rb, int bits) {
assert(bits <= 31);
int value = 0, bit;
for (bit = bits - 1; bit >= 0; bit--) value |= aom_rb_read_bit(rb) << bit;
return value;
}
uint32_t aom_rb_read_unsigned_literal(struct aom_read_bit_buffer *rb,
int bits) {
assert(bits <= 32);
uint32_t value = 0;
int bit;
for (bit = bits - 1; bit >= 0; bit--)
value |= (uint32_t)aom_rb_read_bit(rb) << bit;
return value;
}
int aom_rb_read_inv_signed_literal(struct aom_read_bit_buffer *rb, int bits) {
const int nbits = sizeof(unsigned) * 8 - bits - 1;
const unsigned value = (unsigned)aom_rb_read_literal(rb, bits + 1) << nbits;
return ((int)value) >> nbits;
}
uint32_t aom_rb_read_uvlc(struct aom_read_bit_buffer *rb) {
int leading_zeros = 0;
while (leading_zeros < 32 && !aom_rb_read_bit(rb)) ++leading_zeros;
// Maximum 32 bits.
if (leading_zeros == 32) return UINT32_MAX;
const uint32_t base = (1u << leading_zeros) - 1;
const uint32_t value = aom_rb_read_literal(rb, leading_zeros);
return base + value;
}
static uint16_t aom_rb_read_primitive_quniform(struct aom_read_bit_buffer *rb,
uint16_t n) {
if (n <= 1) return 0;
const int l = get_msb(n) + 1;
const int m = (1 << l) - n;
const int v = aom_rb_read_literal(rb, l - 1);
return v < m ? v : (v << 1) - m + aom_rb_read_bit(rb);
}
static uint16_t aom_rb_read_primitive_subexpfin(struct aom_read_bit_buffer *rb,
uint16_t n, uint16_t k) {
int i = 0;
int mk = 0;
while (1) {
int b = (i ? k + i - 1 : k);
int a = (1 << b);
if (n <= mk + 3 * a) {
return aom_rb_read_primitive_quniform(rb, n - mk) + mk;
}
if (!aom_rb_read_bit(rb)) {
return aom_rb_read_literal(rb, b) + mk;
}
i = i + 1;
mk += a;
}
assert(0);
return 0;
}
static uint16_t aom_rb_read_primitive_refsubexpfin(
struct aom_read_bit_buffer *rb, uint16_t n, uint16_t k, uint16_t ref) {
return inv_recenter_finite_nonneg(n, ref,
aom_rb_read_primitive_subexpfin(rb, n, k));
}
int16_t aom_rb_read_signed_primitive_refsubexpfin(
struct aom_read_bit_buffer *rb, uint16_t n, uint16_t k, int16_t ref) {
ref += n - 1;
const uint16_t scaled_n = (n << 1) - 1;
return aom_rb_read_primitive_refsubexpfin(rb, scaled_n, k, ref) - n + 1;
}
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