ref: 3244f4738d16cfef982ebf94e70dadd95d4c47b8
dir: /vp8/encoder/boolhuff.h/
/* * 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. */ /**************************************************************************** * * Module Title : boolhuff.h * * Description : Bool Coder header file. * ****************************************************************************/ #ifndef VPX_VP8_ENCODER_BOOLHUFF_H_ #define VPX_VP8_ENCODER_BOOLHUFF_H_ #include "vpx_ports/mem.h" #include "vpx/internal/vpx_codec_internal.h" #ifdef __cplusplus extern "C" { #endif typedef struct { unsigned int lowvalue; unsigned int range; int count; unsigned int pos; unsigned char *buffer; unsigned char *buffer_end; struct vpx_internal_error_info *error; } BOOL_CODER; void vp8_start_encode(BOOL_CODER *bc, unsigned char *source, unsigned char *source_end); void vp8_encode_value(BOOL_CODER *bc, int data, int bits); void vp8_stop_encode(BOOL_CODER *bc); extern const unsigned int vp8_prob_cost[256]; DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]); static int validate_buffer(const unsigned char *start, size_t len, const unsigned char *end, struct vpx_internal_error_info *error) { if (start + len > start && start + len < end) { return 1; } else { vpx_internal_error(error, VPX_CODEC_CORRUPT_FRAME, "Truncated packet or corrupt partition "); } return 0; } static void vp8_encode_bool(BOOL_CODER *bc, int bit, int probability) { unsigned int split; int count = bc->count; unsigned int range = bc->range; unsigned int lowvalue = bc->lowvalue; int shift; split = 1 + (((range - 1) * probability) >> 8); range = split; if (bit) { lowvalue += split; range = bc->range - split; } shift = vp8_norm[range]; range <<= shift; count += shift; if (count >= 0) { int offset = shift - count; if ((lowvalue << (offset - 1)) & 0x80000000) { int x = bc->pos - 1; while (x >= 0 && bc->buffer[x] == 0xff) { bc->buffer[x] = (unsigned char)0; x--; } bc->buffer[x] += 1; } validate_buffer(bc->buffer + bc->pos, 1, bc->buffer_end, bc->error); bc->buffer[bc->pos++] = (lowvalue >> (24 - offset)); lowvalue <<= offset; shift = count; lowvalue &= 0xffffff; count -= 8; } lowvalue <<= shift; bc->count = count; bc->lowvalue = lowvalue; bc->range = range; } #ifdef __cplusplus } // extern "C" #endif #endif // VPX_VP8_ENCODER_BOOLHUFF_H_