2 * Copyright (c) 2010 The WebM project authors. All Rights Reserved.
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
12 #include "dboolhuff.h"
13 #include "vp8/common/common.h"
15 int vp8dx_start_decode(BOOL_DECODER *br,
16 const unsigned char *source,
17 unsigned int source_sz,
18 vpx_decrypt_cb decrypt_cb,
21 br->user_buffer_end = source+source_sz;
22 br->user_buffer = source;
26 br->decrypt_cb = decrypt_cb;
27 br->decrypt_state = decrypt_state;
29 if (source_sz && !source)
32 /* Populate the buffer */
33 vp8dx_bool_decoder_fill(br);
38 void vp8dx_bool_decoder_fill(BOOL_DECODER *br)
40 const unsigned char *bufptr = br->user_buffer;
41 VP8_BD_VALUE value = br->value;
42 int count = br->count;
43 int shift = VP8_BD_VALUE_SIZE - CHAR_BIT - (count + CHAR_BIT);
44 size_t bytes_left = br->user_buffer_end - bufptr;
45 size_t bits_left = bytes_left * CHAR_BIT;
46 int x = (int)(shift + CHAR_BIT - bits_left);
48 unsigned char decrypted[sizeof(VP8_BD_VALUE) + 1];
51 size_t n = MIN(sizeof(decrypted), bytes_left);
52 br->decrypt_cb(br->decrypt_state, bufptr, decrypted, (int)n);
58 count += VP8_LOTS_OF_BITS;
62 if (x < 0 || bits_left)
64 while(shift >= loop_end)
67 value |= (VP8_BD_VALUE)*bufptr << shift;