-
Dmitry Kovalev authored
Removing redundant code, lower case variable names, better indentation, better parameter names, adding const to readonly parameters. Change-Id: Ibfdee00f60316fdc5b3f024028c7aaa76a627483
180cd5fa
/* * Copyright (c) 2010 The WebM project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */#ifndef VP9_DECODER_VP9_DBOOLHUFF_H_#define VP9_DECODER_VP9_DBOOLHUFF_H_#include <stddef.h>#include <limits.h>#include "./vpx_config.h"#include "vpx_ports/mem.h"#include "vpx/vpx_integer.h"typedef size_t VP9_BD_VALUE;#define VP9_BD_VALUE_SIZE ((int)sizeof(VP9_BD_VALUE)*CHAR_BIT)/*This is meant to be a large, positive constant that can still be efficiently loaded as an immediate (on platforms like ARM, for example). Even relatively modest values like 100 would work fine.*/#define VP9_LOTS_OF_BITS (0x40000000)typedef struct { const unsigned char *user_buffer_end; const unsigned char *user_buffer; VP9_BD_VALUE value; int count; unsigned int range;} BOOL_DECODER;DECLARE_ALIGNED(16, extern const uint8_t, vp9_norm[256]);int vp9_start_decode(BOOL_DECODER *br, const unsigned char *source, unsigned int source_sz);void vp9_bool_decoder_fill(BOOL_DECODER *br);int vp9_decode_uniform(BOOL_DECODER *br, int n);int vp9_decode_term_subexp(BOOL_DECODER *br, int k, int num_syms);int vp9_inv_recenter_nonneg(int v, int m);static int decode_bool(BOOL_DECODER *br, int probability) { unsigned int bit = 0; VP9_BD_VALUE value; VP9_BD_VALUE bigsplit; int count; unsigned int range; unsigned int split = 1 + (((br->range - 1) * probability) >> 8); if (br->count < 0) vp9_bool_decoder_fill(br); value = br->value; count = br->count; bigsplit = (VP9_BD_VALUE)split << (VP9_BD_VALUE_SIZE - 8); range = split; if (value >= bigsplit) { range = br->range - split; value = value - bigsplit; bit = 1;7172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118
}
{
register unsigned int shift = vp9_norm[range];
range <<= shift;
value <<= shift;
count -= shift;
}
br->value = value;
br->count = count;
br->range = range;
return bit;
}
static int decode_value(BOOL_DECODER *br, int bits) {
int z = 0;
int bit;
for (bit = bits - 1; bit >= 0; bit--) {
z |= decode_bool(br, 0x80) << bit;
}
return z;
}
static int bool_error(BOOL_DECODER *br) {
// Check if we have reached the end of the buffer.
//
// Variable 'count' stores the number of bits in the 'value' buffer, minus
// 8. The top byte is part of the algorithm, and the remainder is buffered
// to be shifted into it. So if count == 8, the top 16 bits of 'value' are
// occupied, 8 for the algorithm and 8 in the buffer.
//
// When reading a byte from the user's buffer, count is filled with 8 and
// one byte is filled into the value buffer. When we reach the end of the
// data, count is additionally filled with VP9_LOTS_OF_BITS. So when
// count == VP9_LOTS_OF_BITS - 1, the user's data has been exhausted.
//
// 1 if we have tried to decode bits after the end of stream was encountered.
// 0 No error.
return br->count > VP9_BD_VALUE_SIZE && br->count < VP9_LOTS_OF_BITS;
}
int vp9_decode_unsigned_max(BOOL_DECODER *br, int max);
#endif // VP9_DECODER_VP9_DBOOLHUFF_H_