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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 <limits.h>
#include <stdlib.h>
#include "config/aom_config.h"
#include "aom_dsp/bitwriter_buffer.h"
#include "aom_dsp/recenter.h"
#include "aom_ports/bitops.h"
int aom_wb_is_byte_aligned(const struct aom_write_bit_buffer *wb) {
return (wb->bit_offset % CHAR_BIT == 0);
}
uint32_t aom_wb_bytes_written(const struct aom_write_bit_buffer *wb) {
return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
}
void aom_wb_write_bit(struct aom_write_bit_buffer *wb, int bit) {
const int off = (int)wb->bit_offset;
const int p = off / CHAR_BIT;
const int q = CHAR_BIT - 1 - off % CHAR_BIT;
if (q == CHAR_BIT - 1) {
// Zero next char and write bit
wb->bit_buffer[p] = bit << q;
} else {
wb->bit_buffer[p] &= ~(1 << q);
wb->bit_buffer[p] |= bit << q;
}
wb->bit_offset = off + 1;
}
static void overwrite_bit(struct aom_write_bit_buffer *wb, int bit) {
// Do not zero bytes but overwrite exisiting values
const int off = (int)wb->bit_offset;
const int p = off / CHAR_BIT;
const int q = CHAR_BIT - 1 - off % CHAR_BIT;
wb->bit_buffer[p] &= ~(1 << q);
wb->bit_buffer[p] |= bit << q;
wb->bit_offset = off + 1;
}
void aom_wb_write_literal(struct aom_write_bit_buffer *wb, int data, int bits) {
assert(bits <= 31);
int bit;
for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
}
void aom_wb_write_unsigned_literal(struct aom_write_bit_buffer *wb,
uint32_t data, int bits) {
assert(bits <= 32);
int bit;
for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
}
void aom_wb_overwrite_literal(struct aom_write_bit_buffer *wb, int data,
int bits) {
int bit;
for (bit = bits - 1; bit >= 0; bit--) overwrite_bit(wb, (data >> bit) & 1);
}
void aom_wb_write_inv_signed_literal(struct aom_write_bit_buffer *wb, int data,
int bits) {
aom_wb_write_literal(wb, data, bits + 1);
}
void aom_wb_write_uvlc(struct aom_write_bit_buffer *wb, uint32_t v) {
assert(v != UINT32_MAX);
++v;
const int leading_zeroes = get_msb(v);
aom_wb_write_literal(wb, 0, leading_zeroes);
aom_wb_write_unsigned_literal(wb, v, leading_zeroes + 1);
}
static void wb_write_primitive_quniform(struct aom_write_bit_buffer *wb,
uint16_t n, uint16_t v) {
if (n <= 1) return;
const int l = get_msb(n) + 1;
const int m = (1 << l) - n;
if (v < m) {
aom_wb_write_literal(wb, v, l - 1);
} else {
aom_wb_write_literal(wb, m + ((v - m) >> 1), l - 1);
aom_wb_write_bit(wb, (v - m) & 1);
}
}
static void wb_write_primitive_subexpfin(struct aom_write_bit_buffer *wb,
uint16_t n, uint16_t k, uint16_t v) {
int i = 0;
int mk = 0;
while (1) {
int b = (i ? k + i - 1 : k);
int a = (1 << b);
if (n <= mk + 3 * a) {
wb_write_primitive_quniform(wb, n - mk, v - mk);
break;
} else {
int t = (v >= mk + a);
aom_wb_write_bit(wb, t);
if (t) {
i = i + 1;
mk += a;
} else {
aom_wb_write_literal(wb, v - mk, b);
break;
}
}
}
}
static void wb_write_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
uint16_t n, uint16_t k,
uint16_t ref, uint16_t v) {
wb_write_primitive_subexpfin(wb, n, k, recenter_finite_nonneg(n, ref, v));
}
void aom_wb_write_signed_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
uint16_t n, uint16_t k,
int16_t ref, int16_t v) {
ref += n - 1;
v += n - 1;
const uint16_t scaled_n = (n << 1) - 1;
wb_write_primitive_refsubexpfin(wb, scaled_n, k, ref, v);
}
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