media/libvpx/vp8/decoder/dboolhuff.c@6474c204b198 (annotated)
media/libvpx/vp8/decoder/dboolhuff.c
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | /* |
| michael@0 | 2 | * Copyright (c) 2010 The WebM project authors. All Rights Reserved. |
| michael@0 | 3 | * |
| michael@0 | 4 | * Use of this source code is governed by a BSD-style license |
| michael@0 | 5 | * that can be found in the LICENSE file in the root of the source |
| michael@0 | 6 | * tree. An additional intellectual property rights grant can be found |
| michael@0 | 7 | * in the file PATENTS. All contributing project authors may |
| michael@0 | 8 | * be found in the AUTHORS file in the root of the source tree. |
| michael@0 | 9 | */ |
| michael@0 | 10 | |
| michael@0 | 11 | |
| michael@0 | 12 | #include "dboolhuff.h" |
| michael@0 | 13 | |
| michael@0 | 14 | int vp8dx_start_decode(BOOL_DECODER *br, |
| michael@0 | 15 | const unsigned char *source, |
| michael@0 | 16 | unsigned int source_sz, |
| michael@0 | 17 | vp8_decrypt_cb *decrypt_cb, |
| michael@0 | 18 | void *decrypt_state) |
| michael@0 | 19 | { |
| michael@0 | 20 | br->user_buffer_end = source+source_sz; |
| michael@0 | 21 | br->user_buffer = source; |
| michael@0 | 22 | br->value = 0; |
| michael@0 | 23 | br->count = -8; |
| michael@0 | 24 | br->range = 255; |
| michael@0 | 25 | br->decrypt_cb = decrypt_cb; |
| michael@0 | 26 | br->decrypt_state = decrypt_state; |
| michael@0 | 27 | |
| michael@0 | 28 | if (source_sz && !source) |
| michael@0 | 29 | return 1; |
| michael@0 | 30 | |
| michael@0 | 31 | /* Populate the buffer */ |
| michael@0 | 32 | vp8dx_bool_decoder_fill(br); |
| michael@0 | 33 | |
| michael@0 | 34 | return 0; |
| michael@0 | 35 | } |
| michael@0 | 36 | |
| michael@0 | 37 | void vp8dx_bool_decoder_fill(BOOL_DECODER *br) |
| michael@0 | 38 | { |
| michael@0 | 39 | const unsigned char *bufptr = br->user_buffer; |
| michael@0 | 40 | VP8_BD_VALUE value = br->value; |
| michael@0 | 41 | int count = br->count; |
| michael@0 | 42 | int shift = VP8_BD_VALUE_SIZE - 8 - (count + 8); |
| michael@0 | 43 | size_t bytes_left = br->user_buffer_end - bufptr; |
| michael@0 | 44 | size_t bits_left = bytes_left * CHAR_BIT; |
| michael@0 | 45 | int x = (int)(shift + CHAR_BIT - bits_left); |
| michael@0 | 46 | int loop_end = 0; |
| michael@0 | 47 | unsigned char decrypted[sizeof(VP8_BD_VALUE) + 1]; |
| michael@0 | 48 | |
| michael@0 | 49 | if (br->decrypt_cb) { |
| michael@0 | 50 | size_t n = bytes_left > sizeof(decrypted) ? sizeof(decrypted) : bytes_left; |
| michael@0 | 51 | br->decrypt_cb(br->decrypt_state, bufptr, decrypted, (int)n); |
| michael@0 | 52 | bufptr = decrypted; |
| michael@0 | 53 | } |
| michael@0 | 54 | |
| michael@0 | 55 | if(x >= 0) |
| michael@0 | 56 | { |
| michael@0 | 57 | count += VP8_LOTS_OF_BITS; |
| michael@0 | 58 | loop_end = x; |
| michael@0 | 59 | } |
| michael@0 | 60 | |
| michael@0 | 61 | if (x < 0 || bits_left) |
| michael@0 | 62 | { |
| michael@0 | 63 | while(shift >= loop_end) |
| michael@0 | 64 | { |
| michael@0 | 65 | count += CHAR_BIT; |
| michael@0 | 66 | value |= (VP8_BD_VALUE)*bufptr << shift; |
| michael@0 | 67 | ++bufptr; |
| michael@0 | 68 | ++br->user_buffer; |
| michael@0 | 69 | shift -= CHAR_BIT; |
| michael@0 | 70 | } |
| michael@0 | 71 | } |
| michael@0 | 72 | |
| michael@0 | 73 | br->value = value; |
| michael@0 | 74 | br->count = count; |
| michael@0 | 75 | } |
