| /* |
| * Copyright (c) 2021, Alliance for Open Media. All rights reserved |
| * |
| * This source code is subject to the terms of the BSD 3-Clause Clear License |
| * and the Alliance for Open Media Patent License 1.0. If the BSD 3-Clause Clear |
| * License was not distributed with this source code in the LICENSE file, you |
| * can obtain it at aomedia.org/license/software-license/bsd-3-c-c/. If the |
| * Alliance for Open Media Patent License 1.0 was not distributed with this |
| * source code in the PATENTS file, you can obtain it at |
| * aomedia.org/license/patent-license/. |
| */ |
| |
| #ifndef AOM_AOM_DSP_ENTDEC_H_ |
| #define AOM_AOM_DSP_ENTDEC_H_ |
| #include <limits.h> |
| #include "aom_dsp/entcode.h" |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| typedef struct od_ec_dec od_ec_dec; |
| |
| #if defined(OD_ACCOUNTING) && OD_ACCOUNTING |
| #define OD_ACC_STR , char *acc_str |
| #define od_ec_dec_bits(dec, ftb, str) od_ec_dec_bits_(dec, ftb, str) |
| #else |
| #define OD_ACC_STR |
| #define od_ec_dec_bits(dec, ftb, str) od_ec_dec_bits_(dec, ftb) |
| #endif |
| |
| /*The entropy decoder context.*/ |
| struct od_ec_dec { |
| /*The start of the current input buffer.*/ |
| const unsigned char *buf; |
| /*An offset used to keep track of tell after reaching the end of the stream. |
| This is constant throughout most of the decoding process, but becomes |
| important once we hit the end of the buffer and stop incrementing bptr |
| (and instead pretend cnt has lots of bits).*/ |
| int32_t tell_offs; |
| /*The end of the current input buffer.*/ |
| const unsigned char *end; |
| /*The read pointer for the entropy-coded bits.*/ |
| const unsigned char *bptr; |
| /*The difference between the high end of the current range, (low + rng), and |
| the coded value, minus 1. |
| This stores up to OD_EC_WINDOW_SIZE bits of that difference, but the |
| decoder only uses the top 16 bits of the window to decode the next symbol. |
| As we shift up during renormalization, if we don't have enough bits left in |
| the window to fill the top 16, we'll read in more bits of the coded |
| value.*/ |
| od_ec_window dif; |
| /*The number of values in the current range.*/ |
| uint16_t rng; |
| /*The number of bits of data in the current value.*/ |
| int16_t cnt; |
| }; |
| |
| /*See entdec.c for further documentation.*/ |
| |
| void od_ec_dec_init(od_ec_dec *dec, const unsigned char *buf, uint32_t storage) |
| OD_ARG_NONNULL(1) OD_ARG_NONNULL(2); |
| |
| OD_WARN_UNUSED_RESULT int od_ec_decode_bool_q15(od_ec_dec *dec, unsigned f) |
| OD_ARG_NONNULL(1); |
| OD_WARN_UNUSED_RESULT int od_ec_decode_cdf_q15(od_ec_dec *dec, |
| const uint16_t *cdf, int nsyms) |
| OD_ARG_NONNULL(1) OD_ARG_NONNULL(2); |
| |
| OD_WARN_UNUSED_RESULT uint32_t od_ec_dec_bits_(od_ec_dec *dec, unsigned ftb) |
| OD_ARG_NONNULL(1); |
| |
| OD_WARN_UNUSED_RESULT int od_ec_dec_tell(const od_ec_dec *dec) |
| OD_ARG_NONNULL(1); |
| OD_WARN_UNUSED_RESULT uint32_t od_ec_dec_tell_frac(const od_ec_dec *dec) |
| OD_ARG_NONNULL(1); |
| |
| #ifdef __cplusplus |
| } // extern "C" |
| #endif |
| |
| #endif // AOM_AOM_DSP_ENTDEC_H_ |