media/libvpx/libvpx/vp8/decoder/dboolhuff.h
author Johann <johannkoenig@google.com>
Mon, 16 Jan 2017 11:51:27 -0800
changeset 376885 70a5310085fa0c77bfcf88c4180c3e3af438a44d
parent 376446 b1c31c4a0a678194931779e0f13fba7b508eb109
child 377112 58764883978d7959d480b9d2722c16f40f63bf96
permissions -rw-r--r--
Bug 1223692: Update libvpx to v1.6.0. r=rillian This includes the following patches: <patch file> <upstream review commit> <upstream hash> 1237848-check-lookahead-ctx.patch https://chromium-review.googlesource.com/324510 4f780e94a1fa54f22256e0f4d42a77c340a38fa1 block_error_fp.patch https://chromium-review.googlesource.com/282611 ff8505a54d0b3dda220f5c0695519c353c82b933 cast-char-to-uint-before-shift.patch https://chromium-review.googlesource.com/345470 2240d83d7882ce2d5d0826b9ce33b86321d7a724 clamp_abs_lvl_seg.patch https://chromium-review.googlesource.com/315754 2e693eb80e705ea68e23eed19616d22b4778b45a clamp-abs-QIndex.patch https://chromium-review.googlesource.com/315802 ff3674a15e5b1a006546e1edc64c3e778eb34ab1 rename_duplicate_files.patch https://chromium-review.googlesource.com/281967 6a82f0d7fb9ee908c389e8d55444bbaed3d54e9c https://chromium-review.googlesource.com/317880 d36659cec7fab96cedc67db4d511ed7135637d0e vp9_filter_restore_aligment.patch https://chromium-review.googlesource.com/276889 33b3953c548a20c0aee705657df0440a740c28b7 vpx_once.patch https://chromium-review.googlesource.com/312467 2635573a7f2e4bbd259379acf91efb97d983359f MozReview-Commit-ID: R7qB6egl3Z

/*
 *  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 VP8_DECODER_DBOOLHUFF_H_
#define VP8_DECODER_DBOOLHUFF_H_

#include <stddef.h>
#include <limits.h>

#include "./vpx_config.h"
#include "vpx_ports/mem.h"
#include "vpx/vp8dx.h"
#include "vpx/vpx_integer.h"

#ifdef __cplusplus
extern "C" {
#endif

typedef size_t VP8_BD_VALUE;

#define VP8_BD_VALUE_SIZE ((int)sizeof(VP8_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 VP8_LOTS_OF_BITS (0x40000000)

typedef struct
{
    const unsigned char *user_buffer_end;
    const unsigned char *user_buffer;
    VP8_BD_VALUE         value;
    int                  count;
    unsigned int         range;
    vpx_decrypt_cb       decrypt_cb;
    void                *decrypt_state;
} BOOL_DECODER;

DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);

int vp8dx_start_decode(BOOL_DECODER *br,
                       const unsigned char *source,
                       unsigned int source_sz,
                       vpx_decrypt_cb decrypt_cb,
                       void *decrypt_state);

void vp8dx_bool_decoder_fill(BOOL_DECODER *br);


static int vp8dx_decode_bool(BOOL_DECODER *br, int probability) {
    unsigned int bit = 0;
    VP8_BD_VALUE value;
    unsigned int split;
    VP8_BD_VALUE bigsplit;
    int count;
    unsigned int range;

    split = 1 + (((br->range - 1) * probability) >> 8);

    if(br->count < 0)
        vp8dx_bool_decoder_fill(br);

    value = br->value;
    count = br->count;

    bigsplit = (VP8_BD_VALUE)split << (VP8_BD_VALUE_SIZE - 8);

    range = split;

    if (value >= bigsplit)
    {
        range = br->range - split;
        value = value - bigsplit;
        bit = 1;
    }

    {
        register int shift = vp8_norm[range];
        range <<= shift;
        value <<= shift;
        count -= shift;
    }
    br->value = value;
    br->count = count;
    br->range = range;

    return bit;
}

static INLINE int vp8_decode_value(BOOL_DECODER *br, int bits)
{
    int z = 0;
    int bit;

    for (bit = bits - 1; bit >= 0; bit--)
    {
        z |= (vp8dx_decode_bool(br, 0x80) << bit);
    }

    return z;
}

static INLINE int vp8dx_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 VP8_LOTS_OF_BITS. So when
     * count == VP8_LOTS_OF_BITS - 1, the user's data has been exhausted.
     */
    if ((br->count > VP8_BD_VALUE_SIZE) && (br->count < VP8_LOTS_OF_BITS))
    {
       /* We have tried to decode bits after the end of
        * stream was encountered.
        */
        return 1;
    }

    /* No error. */
    return 0;
}

#ifdef __cplusplus
}  // extern "C"
#endif

#endif  // VP8_DECODER_DBOOLHUFF_H_