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/*
* 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.
*/
/****************************************************************************
*
* Module Title : boolhuff.h
*
* Description : Bool Coder header file.
*
****************************************************************************/
#ifndef VP8_ENCODER_BOOLHUFF_H_
#define VP8_ENCODER_BOOLHUFF_H_
#include "vpx_ports/mem.h"
#include "vpx/internal/vpx_codec_internal.h"
#ifdef __cplusplus
extern "C" {
#endif
typedef struct
{
unsigned int lowvalue;
unsigned int range;
int count;
unsigned int pos;
unsigned char *buffer;
unsigned char *buffer_end;
struct vpx_internal_error_info *error;
} BOOL_CODER;
extern void vp8_start_encode(BOOL_CODER *bc, unsigned char *buffer, unsigned char *buffer_end);
extern void vp8_encode_value(BOOL_CODER *br, int data, int bits);
extern void vp8_stop_encode(BOOL_CODER *bc);
extern const unsigned int vp8_prob_cost[256];
DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);
static int validate_buffer(const unsigned char *start,
size_t len,
const unsigned char *end,
struct vpx_internal_error_info *error)
{
if (start + len > start && start + len < end)
return 1;
else
vpx_internal_error(error, VPX_CODEC_CORRUPT_FRAME,
"Truncated packet or corrupt partition ");
return 0;
}
static void vp8_encode_bool(BOOL_CODER *br, int bit, int probability)
{
unsigned int split;
int count = br->count;
unsigned int range = br->range;
unsigned int lowvalue = br->lowvalue;
register unsigned int shift;
#ifdef VP8_ENTROPY_STATS
#if defined(SECTIONBITS_OUTPUT)
if (bit)
Sectionbits[active_section] += vp8_prob_cost[255-probability];
else
Sectionbits[active_section] += vp8_prob_cost[probability];
#endif
#endif
split = 1 + (((range - 1) * probability) >> 8);
range = split;
if (bit)
{
lowvalue += split;
range = br->range - split;
}
shift = vp8_norm[range];
range <<= shift;
count += shift;
if (count >= 0)
{
int offset = shift - count;
if ((lowvalue << (offset - 1)) & 0x80000000)
{
int x = br->pos - 1;
while (x >= 0 && br->buffer[x] == 0xff)
{
br->buffer[x] = (unsigned char)0;
x--;
}
br->buffer[x] += 1;
}
validate_buffer(br->buffer + br->pos, 1, br->buffer_end, br->error);
br->buffer[br->pos++] = (lowvalue >> (24 - offset));
lowvalue <<= offset;
shift = count;
lowvalue &= 0xffffff;
count -= 8 ;
}
lowvalue <<= shift;
br->count = count;
br->lowvalue = lowvalue;
br->range = range;
}
#ifdef __cplusplus
} // extern "C"
#endif
#endif // VP8_ENCODER_BOOLHUFF_H_
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