Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
       3             :  *
       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.
       9             :  */
      10             : 
      11             : /****************************************************************************
      12             : *
      13             : *   Module Title :     boolhuff.h
      14             : *
      15             : *   Description  :     Bool Coder header file.
      16             : *
      17             : ****************************************************************************/
      18             : #ifndef VP8_ENCODER_BOOLHUFF_H_
      19             : #define VP8_ENCODER_BOOLHUFF_H_
      20             : 
      21             : #include "vpx_ports/mem.h"
      22             : #include "vpx/internal/vpx_codec_internal.h"
      23             : 
      24             : #ifdef __cplusplus
      25             : extern "C" {
      26             : #endif
      27             : 
      28             : typedef struct {
      29             :   unsigned int lowvalue;
      30             :   unsigned int range;
      31             :   int count;
      32             :   unsigned int pos;
      33             :   unsigned char *buffer;
      34             :   unsigned char *buffer_end;
      35             :   struct vpx_internal_error_info *error;
      36             : } BOOL_CODER;
      37             : 
      38             : extern void vp8_start_encode(BOOL_CODER *bc, unsigned char *buffer,
      39             :                              unsigned char *buffer_end);
      40             : 
      41             : extern void vp8_encode_value(BOOL_CODER *br, int data, int bits);
      42             : extern void vp8_stop_encode(BOOL_CODER *bc);
      43             : extern const unsigned int vp8_prob_cost[256];
      44             : 
      45             : DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);
      46             : 
      47           0 : static int validate_buffer(const unsigned char *start, size_t len,
      48             :                            const unsigned char *end,
      49             :                            struct vpx_internal_error_info *error) {
      50           0 :   if (start + len > start && start + len < end) {
      51           0 :     return 1;
      52             :   } else {
      53           0 :     vpx_internal_error(error, VPX_CODEC_CORRUPT_FRAME,
      54             :                        "Truncated packet or corrupt partition ");
      55             :   }
      56             : 
      57           0 :   return 0;
      58             : }
      59           0 : static void vp8_encode_bool(BOOL_CODER *br, int bit, int probability) {
      60             :   unsigned int split;
      61           0 :   int count = br->count;
      62           0 :   unsigned int range = br->range;
      63           0 :   unsigned int lowvalue = br->lowvalue;
      64             :   register int shift;
      65             : 
      66             : #ifdef VP8_ENTROPY_STATS
      67             : #if defined(SECTIONBITS_OUTPUT)
      68             : 
      69             :   if (bit)
      70             :     Sectionbits[active_section] += vp8_prob_cost[255 - probability];
      71             :   else
      72             :     Sectionbits[active_section] += vp8_prob_cost[probability];
      73             : 
      74             : #endif
      75             : #endif
      76             : 
      77           0 :   split = 1 + (((range - 1) * probability) >> 8);
      78             : 
      79           0 :   range = split;
      80             : 
      81           0 :   if (bit) {
      82           0 :     lowvalue += split;
      83           0 :     range = br->range - split;
      84             :   }
      85             : 
      86           0 :   shift = vp8_norm[range];
      87             : 
      88           0 :   range <<= shift;
      89           0 :   count += shift;
      90             : 
      91           0 :   if (count >= 0) {
      92           0 :     int offset = shift - count;
      93             : 
      94           0 :     if ((lowvalue << (offset - 1)) & 0x80000000) {
      95           0 :       int x = br->pos - 1;
      96             : 
      97           0 :       while (x >= 0 && br->buffer[x] == 0xff) {
      98           0 :         br->buffer[x] = (unsigned char)0;
      99           0 :         x--;
     100             :       }
     101             : 
     102           0 :       br->buffer[x] += 1;
     103             :     }
     104             : 
     105           0 :     validate_buffer(br->buffer + br->pos, 1, br->buffer_end, br->error);
     106           0 :     br->buffer[br->pos++] = (lowvalue >> (24 - offset));
     107             : 
     108           0 :     lowvalue <<= offset;
     109           0 :     shift = count;
     110           0 :     lowvalue &= 0xffffff;
     111           0 :     count -= 8;
     112             :   }
     113             : 
     114           0 :   lowvalue <<= shift;
     115           0 :   br->count = count;
     116           0 :   br->lowvalue = lowvalue;
     117           0 :   br->range = range;
     118           0 : }
     119             : 
     120             : #ifdef __cplusplus
     121             : }  // extern "C"
     122             : #endif
     123             : 
     124             : #endif  // VP8_ENCODER_BOOLHUFF_H_