/* *  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. */  #include "dboolhuff.h" int vp8dx_start_decode(BOOL_DECODER *br,                       const unsigned char *source,                       unsigned int source_sz,                       vp8_decrypt_cb *decrypt_cb,                       void *decrypt_state){    br->user_buffer_end = source+source_sz;    br->user_buffer     = source;    br->value    = 0;    br->count    = -8;    br->range    = 255;    br->decrypt_cb = decrypt_cb;    br->decrypt_state = decrypt_state;     if (source_sz && !source)        return 1;     /* Populate the buffer */    vp8dx_bool_decoder_fill(br);     return 0;} void vp8dx_bool_decoder_fill(BOOL_DECODER *br){    const unsigned char *bufptr = br->user_buffer;    VP8_BD_VALUE value = br->value;    int count = br->count;    int shift = VP8_BD_VALUE_SIZE - 8 - (count + 8);    size_t bytes_left = br->user_buffer_end - bufptr;    size_t bits_left = bytes_left * CHAR_BIT;    int x = (int)(shift + CHAR_BIT - bits_left);    int loop_end = 0;    unsigned char decrypted[sizeof(VP8_BD_VALUE) + 1];     if (br->decrypt_cb) {        size_t n = bytes_left > sizeof(decrypted) ? sizeof(decrypted) : bytes_left;        br->decrypt_cb(br->decrypt_state, bufptr, decrypted, (int)n);        bufptr = decrypted;    }     if(x >= 0)    {        count += VP8_LOTS_OF_BITS;        loop_end = x;    }     if (x < 0 || bits_left)    {        while(shift >= loop_end)        {            count += CHAR_BIT;            value |= (VP8_BD_VALUE)*bufptr << shift;            ++bufptr;            ++br->user_buffer;            shift -= CHAR_BIT;        }    }     br->value = value;    br->count = count;}