67d060067e
This is the first CL with vp9_reader changes. All another macro definitions will be replaced after. Change-Id: I1c6bd9c9a612ec1663d484d6adb4fb720af54063
121 lines
2.7 KiB
C
121 lines
2.7 KiB
C
/*
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* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "vpx_ports/mem.h"
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#include "vpx_mem/vpx_mem.h"
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#include "vp9/decoder/vp9_dboolhuff.h"
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int vp9_start_decode(BOOL_DECODER *br, const uint8_t *buffer, size_t size) {
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br->buffer_end = buffer + size;
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br->buffer = buffer;
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br->value = 0;
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br->count = -8;
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br->range = 255;
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if (size && !buffer)
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return 1;
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vp9_reader_fill(br);
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return 0;
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}
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void vp9_reader_fill(BOOL_DECODER *br) {
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const uint8_t *const buffer_end = br->buffer_end;
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const uint8_t *buffer = br->buffer;
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VP9_BD_VALUE value = br->value;
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int count = br->count;
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int shift = VP9_BD_VALUE_SIZE - 8 - (count + 8);
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int loop_end = 0;
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const int bits_left = (int)((buffer_end - buffer)*CHAR_BIT);
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const int x = shift + CHAR_BIT - bits_left;
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if (x >= 0) {
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count += VP9_LOTS_OF_BITS;
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loop_end = x;
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}
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if (x < 0 || bits_left) {
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while (shift >= loop_end) {
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count += CHAR_BIT;
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value |= (VP9_BD_VALUE)*buffer++ << shift;
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shift -= CHAR_BIT;
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}
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}
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br->buffer = buffer;
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br->value = value;
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br->count = count;
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}
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static int get_unsigned_bits(unsigned int num_values) {
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int cat = 0;
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if (num_values <= 1)
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return 0;
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num_values--;
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while (num_values > 0) {
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cat++;
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num_values >>= 1;
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}
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return cat;
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}
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int vp9_inv_recenter_nonneg(int v, int m) {
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if (v > (m << 1))
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return v;
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else if ((v & 1) == 0)
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return (v >> 1) + m;
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else
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return m - ((v + 1) >> 1);
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}
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int vp9_decode_uniform(BOOL_DECODER *br, int n) {
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int v;
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const int l = get_unsigned_bits(n);
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const int m = (1 << l) - n;
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if (!l)
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return 0;
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v = vp9_read_literal(br, l - 1);
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return v < m ? v : (v << 1) - m + vp9_read_bit(br);
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}
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int vp9_decode_term_subexp(BOOL_DECODER *br, int k, int num_syms) {
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int i = 0, mk = 0, word;
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while (1) {
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const int b = i ? k + i - 1 : k;
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const int a = 1 << b;
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if (num_syms <= mk + 3 * a) {
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word = vp9_decode_uniform(br, num_syms - mk) + mk;
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break;
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} else {
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if (vp9_read_bit(br)) {
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i++;
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mk += a;
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} else {
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word = vp9_read_literal(br, b) + mk;
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break;
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}
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}
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}
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return word;
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}
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int vp9_decode_unsigned_max(BOOL_DECODER *br, int max) {
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int data = 0, bit = 0, lmax = max;
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while (lmax) {
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data |= vp9_read_bit(br) << bit++;
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lmax >>= 1;
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}
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return data > max ? max : data;
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}
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