media/libopus/celt/entcode.h

   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 #include "opus_defines.h"
  30
  31 #if !defined(_entcode_H)
  32 # define _entcode_H (1)
  33 # include <limits.h>
  34 # include <stddef.h>
  35 # include "ecintrin.h"
  36
  37 extern const opus_uint32 SMALL_DIV_TABLE[129];
  38
  39 #ifdef OPUS_ARM_ASM
  40 #define USE_SMALL_DIV_TABLE
  41 #endif
  42
  43 /*OPT: ec_window must be at least 32 bits, but if you have fast arithmetic on a
  44    larger type, you can speed up the decoder by using it here.*/
  45 typedef opus_uint32           ec_window;
  46 typedef struct ec_ctx         ec_ctx;
  47 typedef struct ec_ctx         ec_enc;
  48 typedef struct ec_ctx         ec_dec;
  49
  50 # define EC_WINDOW_SIZE ((int)sizeof(ec_window)*CHAR_BIT)
  51
  52 /*The number of bits to use for the range-coded part of unsigned integers.*/
  53 # define EC_UINT_BITS   (8)
  54
  55 /*The resolution of fractional-precision bit usage measurements, i.e.,
  56    3 => 1/8th bits.*/
  57 # define BITRES 3
  58
  59 /*The entropy encoder/decoder context.
  60   We use the same structure for both, so that common functions like ec_tell()
  61    can be used on either one.*/
  62 struct ec_ctx{
  63    /*Buffered input/output.*/
  64    unsigned char *buf;
  65    /*The size of the buffer.*/
  66    opus_uint32    storage;
  67    /*The offset at which the last byte containing raw bits was read/written.*/
  68    opus_uint32    end_offs;
  69    /*Bits that will be read from/written at the end.*/
  70    ec_window      end_window;
  71    /*Number of valid bits in end_window.*/
  72    int            nend_bits;
  73    /*The total number of whole bits read/written.
  74      This does not include partial bits currently in the range coder.*/
  75    int            nbits_total;
  76    /*The offset at which the next range coder byte will be read/written.*/
  77    opus_uint32    offs;
  78    /*The number of values in the current range.*/
  79    opus_uint32    rng;
  80    /*In the decoder: the difference between the top of the current range and
  81       the input value, minus one.
  82      In the encoder: the low end of the current range.*/
  83    opus_uint32    val;
  84    /*In the decoder: the saved normalization factor from ec_decode().
  85      In the encoder: the number of oustanding carry propagating symbols.*/
  86    opus_uint32    ext;
  87    /*A buffered input/output symbol, awaiting carry propagation.*/
  88    int            rem;
  89    /*Nonzero if an error occurred.*/
  90    int            error;
  91 };
  92
  93 static OPUS_INLINE opus_uint32 ec_range_bytes(ec_ctx *_this){
  94   return _this->offs;
  95 }
  96
  97 static OPUS_INLINE unsigned char *ec_get_buffer(ec_ctx *_this){
  98   return _this->buf;
  99 }
 100
 101 static OPUS_INLINE int ec_get_error(ec_ctx *_this){
 102   return _this->error;
 103 }
 104
 105 /*Returns the number of bits "used" by the encoded or decoded symbols so far.
 106   This same number can be computed in either the encoder or the decoder, and is
 107    suitable for making coding decisions.
 108   Return: The number of bits.
 109           This will always be slightly larger than the exact value (e.g., all
 110            rounding error is in the positive direction).*/
 111 static OPUS_INLINE int ec_tell(ec_ctx *_this){
 112   return _this->nbits_total-EC_ILOG(_this->rng);
 113 }
 114
 115 /*Returns the number of bits "used" by the encoded or decoded symbols so far.
 116   This same number can be computed in either the encoder or the decoder, and is
 117    suitable for making coding decisions.
 118   Return: The number of bits scaled by 2**BITRES.
 119           This will always be slightly larger than the exact value (e.g., all
 120            rounding error is in the positive direction).*/
 121 opus_uint32 ec_tell_frac(ec_ctx *_this);
 122
 123 /* Tested exhaustively for all n and for 1<=d<=256 */
 124 static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) {
 125    celt_sig_assert(d>0);
 126 #ifdef USE_SMALL_DIV_TABLE
 127    if (d>256)
 128       return n/d;
 129    else {
 130       opus_uint32 t, q;
 131       t = EC_ILOG(d&-d);
 132       q = (opus_uint64)SMALL_DIV_TABLE[d>>t]*(n>>(t-1))>>32;
 133       return q+(n-q*d >= d);
 134    }
 135 #else
 136    return n/d;
 137 #endif
 138 }
 139
 140 static OPUS_INLINE opus_int32 celt_sudiv(opus_int32 n, opus_int32 d) {
 141    celt_sig_assert(d>0);
 142 #ifdef USE_SMALL_DIV_TABLE
 143    if (n<0)
 144       return -(opus_int32)celt_udiv(-n, d);
 145    else
 146       return celt_udiv(n, d);
 147 #else
 148    return n/d;
 149 #endif
 150 }
 151
 152 #endif