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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 "aom_dsp/recenter.h"
#define read_primitive_quniform(r, n, ACCT_STR_NAME) \
read_primitive_quniform_(r, n ACCT_STR_ARG(ACCT_STR_NAME))
#define read_primitive_subexpfin(r, n, k, ACCT_STR_NAME) \
read_primitive_subexpfin_(r, n, k ACCT_STR_ARG(ACCT_STR_NAME))
static uint16_t read_primitive_quniform_(aom_reader *r,
uint16_t n ACCT_STR_PARAM) {
if (n <= 1) return 0;
const int l = get_msb(n) + 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);
}
// Decode finite subexponential code that for a symbol v in [0, n-1] with
// parameter k
static uint16_t 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 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;
}
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, read_primitive_subexpfin(r, n, k, ACCT_STR_NAME));
}
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