140 lines
4.4 KiB
C
140 lines
4.4 KiB
C
/*
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* Copyright (c) 2016, Alliance for Open Media. All rights reserved.
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*
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* This source code is subject to the terms of the BSD 2 Clause License and
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* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
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* was not distributed with this source code in the LICENSE file, you can
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* obtain it at www.aomedia.org/license/software. If the Alliance for Open
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* Media Patent License 1.0 was not distributed with this source code in the
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* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
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*/
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#include <assert.h>
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#include <limits.h>
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#include <stdlib.h>
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#include "config/aom_config.h"
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#include "aom_dsp/bitwriter_buffer.h"
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#include "aom_dsp/recenter.h"
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#include "aom_ports/bitops.h"
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int aom_wb_is_byte_aligned(const struct aom_write_bit_buffer *wb) {
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return (wb->bit_offset % CHAR_BIT == 0);
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}
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uint32_t aom_wb_bytes_written(const struct aom_write_bit_buffer *wb) {
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return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
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}
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void aom_wb_write_bit(struct aom_write_bit_buffer *wb, int bit) {
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const int off = (int)wb->bit_offset;
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const int p = off / CHAR_BIT;
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const int q = CHAR_BIT - 1 - off % CHAR_BIT;
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if (q == CHAR_BIT - 1) {
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// Zero next char and write bit
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wb->bit_buffer[p] = bit << q;
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} else {
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wb->bit_buffer[p] &= ~(1 << q);
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wb->bit_buffer[p] |= bit << q;
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}
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wb->bit_offset = off + 1;
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}
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static void overwrite_bit(struct aom_write_bit_buffer *wb, int bit) {
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// Do not zero bytes but overwrite exisiting values
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const int off = (int)wb->bit_offset;
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const int p = off / CHAR_BIT;
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const int q = CHAR_BIT - 1 - off % CHAR_BIT;
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wb->bit_buffer[p] &= ~(1 << q);
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wb->bit_buffer[p] |= bit << q;
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wb->bit_offset = off + 1;
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}
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void aom_wb_write_literal(struct aom_write_bit_buffer *wb, int data, int bits) {
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assert(bits <= 31);
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int bit;
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for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
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}
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void aom_wb_write_unsigned_literal(struct aom_write_bit_buffer *wb,
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uint32_t data, int bits) {
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assert(bits <= 32);
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int bit;
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for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
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}
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void aom_wb_overwrite_literal(struct aom_write_bit_buffer *wb, int data,
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int bits) {
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int bit;
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for (bit = bits - 1; bit >= 0; bit--) overwrite_bit(wb, (data >> bit) & 1);
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}
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void aom_wb_write_inv_signed_literal(struct aom_write_bit_buffer *wb, int data,
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int bits) {
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aom_wb_write_literal(wb, data, bits + 1);
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}
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void aom_wb_write_uvlc(struct aom_write_bit_buffer *wb, uint32_t v) {
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int64_t shift_val = ++v;
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int leading_zeroes = 1;
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assert(shift_val > 0);
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while (shift_val >>= 1) leading_zeroes += 2;
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aom_wb_write_literal(wb, 0, leading_zeroes >> 1);
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aom_wb_write_unsigned_literal(wb, v, (leading_zeroes + 1) >> 1);
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}
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static void wb_write_primitive_quniform(struct aom_write_bit_buffer *wb,
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uint16_t n, uint16_t v) {
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if (n <= 1) return;
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const int l = get_msb(n) + 1;
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const int m = (1 << l) - n;
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if (v < m) {
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aom_wb_write_literal(wb, v, l - 1);
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} else {
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aom_wb_write_literal(wb, m + ((v - m) >> 1), l - 1);
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aom_wb_write_bit(wb, (v - m) & 1);
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}
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}
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static void wb_write_primitive_subexpfin(struct aom_write_bit_buffer *wb,
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uint16_t n, uint16_t k, uint16_t v) {
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int i = 0;
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int mk = 0;
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while (1) {
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int b = (i ? k + i - 1 : k);
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int a = (1 << b);
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if (n <= mk + 3 * a) {
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wb_write_primitive_quniform(wb, n - mk, v - mk);
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break;
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} else {
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int t = (v >= mk + a);
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aom_wb_write_bit(wb, t);
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if (t) {
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i = i + 1;
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mk += a;
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} else {
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aom_wb_write_literal(wb, v - mk, b);
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break;
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}
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}
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}
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}
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static void wb_write_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
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uint16_t n, uint16_t k,
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uint16_t ref, uint16_t v) {
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wb_write_primitive_subexpfin(wb, n, k, recenter_finite_nonneg(n, ref, v));
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}
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void aom_wb_write_signed_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
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uint16_t n, uint16_t k,
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int16_t ref, int16_t v) {
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ref += n - 1;
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v += n - 1;
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const uint16_t scaled_n = (n << 1) - 1;
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wb_write_primitive_refsubexpfin(wb, scaled_n, k, ref, v);
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}
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