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/*
* Copyright (c) 2017, 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 "aom_dsp/binary_codes_reader.h"
#include "av1/common/common.h"
// Inverse recenters a non-negative literal v around a reference r
static uint16_t inv_recenter_nonneg(uint16_t r, uint16_t v) {
if (v > (r << 1))
return v;
else if ((v & 1) == 0)
return (v >> 1) + r;
else
return r - ((v + 1) >> 1);
}
// Inverse recenters a non-negative literal v in [0, n-1] around a
// reference r also in [0, n-1]
static uint16_t inv_recenter_finite_nonneg(uint16_t n, uint16_t r, uint16_t v) {
if ((r << 1) <= n) {
return inv_recenter_nonneg(r, v);
} else {
return n - 1 - inv_recenter_nonneg(n - 1 - r, v);
}
}
uint16_t aom_read_primitive_quniform_(aom_reader *r,
uint16_t n ACCT_STR_PARAM) {
if (n <= 1) return 0;
const int l = get_msb(n - 1) + 1;
const int m = (1 << l) - n;
const int v = aom_read_literal(r, l - 1, ACCT_STR_NAME);
return v < m ? v : (v << 1) - m + aom_read_bit(r, ACCT_STR_NAME);
}
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) + 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);
}
// Decode finite subexponential code that for a symbol v in [0, n-1] with
// parameter k
uint16_t aom_read_primitive_subexpfin_(aom_reader *r, uint16_t n,
uint16_t k ACCT_STR_PARAM) {
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_read_primitive_quniform(r, n - mk, ACCT_STR_NAME) + mk;
}
if (!aom_read_bit(r, ACCT_STR_NAME)) {
return aom_read_literal(r, b, ACCT_STR_NAME) + mk;
}
i = i + 1;
mk += a;
}
assert(0);
return 0;
}
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;
}
uint16_t aom_read_primitive_refsubexpfin_(aom_reader *r, uint16_t n, uint16_t k,
uint16_t ref ACCT_STR_PARAM) {
return inv_recenter_finite_nonneg(
n, ref, aom_read_primitive_subexpfin(r, n, k, ACCT_STR_NAME));
}
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;
}
uint32_t aom_rb_read_uvlc(struct aom_read_bit_buffer *rb) {
int leading_zeros = 0;
while (!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;
}
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