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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 VPX_VP8_ENCODER_BOOLHUFF_H_
#define VPX_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;
void vp8_start_encode(BOOL_CODER *bc, unsigned char *source,
unsigned char *source_end);
void vp8_encode_value(BOOL_CODER *bc, int data, int bits);
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 *bc, int bit, int probability) {
unsigned int split;
int count = bc->count;
unsigned int range = bc->range;
unsigned int lowvalue = bc->lowvalue;
int shift;
split = 1 + (((range - 1) * probability) >> 8);
range = split;
if (bit) {
lowvalue += split;
range = bc->range - split;
}
shift = vp8_norm[range];
range <<= shift;
count += shift;
if (count >= 0) {
int offset = shift - count;
if ((lowvalue << (offset - 1)) & 0x80000000) {
int x = bc->pos - 1;
while (x >= 0 && bc->buffer[x] == 0xff) {
bc->buffer[x] = (unsigned char)0;
x--;
}
bc->buffer[x] += 1;
}
validate_buffer(bc->buffer + bc->pos, 1, bc->buffer_end, bc->error);
bc->buffer[bc->pos++] = (lowvalue >> (24 - offset) & 0xff);
shift = count;
lowvalue = (int)(((uint64_t)lowvalue << offset) & 0xffffff);
count -= 8;
}
lowvalue <<= shift;
bc->count = count;
bc->lowvalue = lowvalue;
bc->range = range;
}
#ifdef __cplusplus
} // extern "C"
#endif
#endif // VPX_VP8_ENCODER_BOOLHUFF_H_
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