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 * 14 * Module Title : boolhuff.h 15 * 16 * Description : Bool Coder header file. 17 * 18 ****************************************************************************/ 19 #ifndef VP8_ENCODER_BOOLHUFF_H_ 20 #define VP8_ENCODER_BOOLHUFF_H_ 21 22 #include "vpx_ports/mem.h" 23 #include "vpx/internal/vpx_codec_internal.h" 24 25 #ifdef __cplusplus 26 extern "C" { 27 #endif 28 29 typedef struct 30 { 31 unsigned int lowvalue; 32 unsigned int range; 33 int count; 34 unsigned int pos; 35 unsigned char *buffer; 36 unsigned char *buffer_end; 37 struct vpx_internal_error_info *error; 38 39 /* Variables used to track bit costs without outputing to the bitstream */ 40 unsigned int measure_cost; 41 unsigned long bit_counter; 42 } BOOL_CODER; 43 44 extern void vp8_start_encode(BOOL_CODER *bc, unsigned char *buffer, unsigned char *buffer_end); 45 46 extern void vp8_encode_value(BOOL_CODER *br, int data, int bits); 47 extern void vp8_stop_encode(BOOL_CODER *bc); 48 extern const unsigned int vp8_prob_cost[256]; 49 50 51 DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]); 52 53 static int validate_buffer(const unsigned char *start, 54 size_t len, 55 const unsigned char *end, 56 struct vpx_internal_error_info *error) 57 { 58 if (start + len > start && start + len < end) 59 return 1; 60 else 61 vpx_internal_error(error, VPX_CODEC_CORRUPT_FRAME, 62 "Truncated packet or corrupt partition "); 63 64 return 0; 65 } 66 static void vp8_encode_bool(BOOL_CODER *br, int bit, int probability) 67 { 68 unsigned int split; 69 int count = br->count; 70 unsigned int range = br->range; 71 unsigned int lowvalue = br->lowvalue; 72 register unsigned int shift; 73 74 #ifdef VP8_ENTROPY_STATS 75 #if defined(SECTIONBITS_OUTPUT) 76 77 if (bit) 78 Sectionbits[active_section] += vp8_prob_cost[255-probability]; 79 else 80 Sectionbits[active_section] += vp8_prob_cost[probability]; 81 82 #endif 83 #endif 84 85 split = 1 + (((range - 1) * probability) >> 8); 86 87 range = split; 88 89 if (bit) 90 { 91 lowvalue += split; 92 range = br->range - split; 93 } 94 95 shift = vp8_norm[range]; 96 97 range <<= shift; 98 count += shift; 99 100 if (count >= 0) 101 { 102 int offset = shift - count; 103 104 if ((lowvalue << (offset - 1)) & 0x80000000) 105 { 106 int x = br->pos - 1; 107 108 while (x >= 0 && br->buffer[x] == 0xff) 109 { 110 br->buffer[x] = (unsigned char)0; 111 x--; 112 } 113 114 br->buffer[x] += 1; 115 } 116 117 validate_buffer(br->buffer + br->pos, 1, br->buffer_end, br->error); 118 br->buffer[br->pos++] = (lowvalue >> (24 - offset)); 119 120 lowvalue <<= offset; 121 shift = count; 122 lowvalue &= 0xffffff; 123 count -= 8 ; 124 } 125 126 lowvalue <<= shift; 127 br->count = count; 128 br->lowvalue = lowvalue; 129 br->range = range; 130 } 131 132 #ifdef __cplusplus 133 } // extern "C" 134 #endif 135 136 #endif // VP8_ENCODER_BOOLHUFF_H_ 137
