Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -0400 | [diff] [blame] | 1 | /* Copyright (c) 2001-2011 Timothy B. Terriberry |
| 2 | Copyright (c) 2008-2009 Xiph.Org Foundation */ |
| 3 | /* |
| 4 | Redistribution and use in source and binary forms, with or without |
| 5 | modification, are permitted provided that the following conditions |
| 6 | are met: |
| 7 | |
| 8 | - Redistributions of source code must retain the above copyright |
| 9 | notice, this list of conditions and the following disclaimer. |
| 10 | |
| 11 | - Redistributions in binary form must reproduce the above copyright |
| 12 | notice, this list of conditions and the following disclaimer in the |
| 13 | documentation and/or other materials provided with the distribution. |
| 14 | |
| 15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 16 | ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 17 | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 18 | A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER |
| 19 | OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| 20 | EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| 21 | PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| 22 | PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| 23 | LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| 24 | NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| 25 | SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 26 | */ |
| 27 | |
| 28 | #include "opus_types.h" |
| 29 | |
| 30 | #if !defined(_entcode_H) |
| 31 | # define _entcode_H (1) |
| 32 | # include <limits.h> |
| 33 | # include <stddef.h> |
| 34 | # include "ecintrin.h" |
| 35 | |
| 36 | /*OPT: ec_window must be at least 32 bits, but if you have fast arithmetic on a |
| 37 | larger type, you can speed up the decoder by using it here.*/ |
| 38 | typedef opus_uint32 ec_window; |
| 39 | typedef struct ec_ctx ec_ctx; |
| 40 | typedef struct ec_ctx ec_enc; |
| 41 | typedef struct ec_ctx ec_dec; |
| 42 | |
| 43 | # define EC_WINDOW_SIZE ((int)sizeof(ec_window)*CHAR_BIT) |
| 44 | |
| 45 | /*The number of bits to use for the range-coded part of unsigned integers.*/ |
| 46 | # define EC_UINT_BITS (8) |
| 47 | |
| 48 | /*The resolution of fractional-precision bit usage measurements, i.e., |
| 49 | 3 => 1/8th bits.*/ |
| 50 | # define BITRES 3 |
| 51 | |
| 52 | /*The entropy encoder/decoder context. |
| 53 | We use the same structure for both, so that common functions like ec_tell() |
| 54 | can be used on either one.*/ |
| 55 | struct ec_ctx{ |
| 56 | /*Buffered input/output.*/ |
| 57 | unsigned char *buf; |
| 58 | /*The size of the buffer.*/ |
| 59 | opus_uint32 storage; |
| 60 | /*The offset at which the last byte containing raw bits was read/written.*/ |
| 61 | opus_uint32 end_offs; |
| 62 | /*Bits that will be read from/written at the end.*/ |
| 63 | ec_window end_window; |
| 64 | /*Number of valid bits in end_window.*/ |
| 65 | int nend_bits; |
| 66 | /*The total number of whole bits read/written. |
| 67 | This does not include partial bits currently in the range coder.*/ |
| 68 | int nbits_total; |
| 69 | /*The offset at which the next range coder byte will be read/written.*/ |
| 70 | opus_uint32 offs; |
| 71 | /*The number of values in the current range.*/ |
| 72 | opus_uint32 rng; |
| 73 | /*In the decoder: the difference between the top of the current range and |
| 74 | the input value, minus one. |
| 75 | In the encoder: the low end of the current range.*/ |
| 76 | opus_uint32 val; |
| 77 | /*In the decoder: the saved normalization factor from ec_decode(). |
| 78 | In the encoder: the number of oustanding carry propagating symbols.*/ |
| 79 | opus_uint32 ext; |
| 80 | /*A buffered input/output symbol, awaiting carry propagation.*/ |
| 81 | int rem; |
| 82 | /*Nonzero if an error occurred.*/ |
| 83 | int error; |
| 84 | }; |
| 85 | |
| 86 | static inline opus_uint32 ec_range_bytes(ec_ctx *_this){ |
| 87 | return _this->offs; |
| 88 | } |
| 89 | |
| 90 | static inline unsigned char *ec_get_buffer(ec_ctx *_this){ |
| 91 | return _this->buf; |
| 92 | } |
| 93 | |
| 94 | static inline int ec_get_error(ec_ctx *_this){ |
| 95 | return _this->error; |
| 96 | } |
| 97 | |
| 98 | /*Returns the number of bits "used" by the encoded or decoded symbols so far. |
| 99 | This same number can be computed in either the encoder or the decoder, and is |
| 100 | suitable for making coding decisions. |
| 101 | Return: The number of bits. |
| 102 | This will always be slightly larger than the exact value (e.g., all |
| 103 | rounding error is in the positive direction).*/ |
| 104 | static inline int ec_tell(ec_ctx *_this){ |
| 105 | return _this->nbits_total-EC_ILOG(_this->rng); |
| 106 | } |
| 107 | |
| 108 | /*Returns the number of bits "used" by the encoded or decoded symbols so far. |
| 109 | This same number can be computed in either the encoder or the decoder, and is |
| 110 | suitable for making coding decisions. |
| 111 | Return: The number of bits scaled by 2**BITRES. |
| 112 | This will always be slightly larger than the exact value (e.g., all |
| 113 | rounding error is in the positive direction).*/ |
| 114 | opus_uint32 ec_tell_frac(ec_ctx *_this); |
| 115 | |
| 116 | #endif |