1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/celt/laplace.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,134 @@
1.4 +/* Copyright (c) 2007 CSIRO
1.5 + Copyright (c) 2007-2009 Xiph.Org Foundation
1.6 + Written by Jean-Marc Valin */
1.7 +/*
1.8 + Redistribution and use in source and binary forms, with or without
1.9 + modification, are permitted provided that the following conditions
1.10 + are met:
1.11 +
1.12 + - Redistributions of source code must retain the above copyright
1.13 + notice, this list of conditions and the following disclaimer.
1.14 +
1.15 + - Redistributions in binary form must reproduce the above copyright
1.16 + notice, this list of conditions and the following disclaimer in the
1.17 + documentation and/or other materials provided with the distribution.
1.18 +
1.19 + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
1.20 + ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
1.21 + LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
1.22 + A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
1.23 + OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
1.24 + EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
1.25 + PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
1.26 + PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
1.27 + LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
1.28 + NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
1.29 + SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.30 +*/
1.31 +
1.32 +#ifdef HAVE_CONFIG_H
1.33 +#include "config.h"
1.34 +#endif
1.35 +
1.36 +#include "laplace.h"
1.37 +#include "mathops.h"
1.38 +
1.39 +/* The minimum probability of an energy delta (out of 32768). */
1.40 +#define LAPLACE_LOG_MINP (0)
1.41 +#define LAPLACE_MINP (1<<LAPLACE_LOG_MINP)
1.42 +/* The minimum number of guaranteed representable energy deltas (in one
1.43 + direction). */
1.44 +#define LAPLACE_NMIN (16)
1.45 +
1.46 +/* When called, decay is positive and at most 11456. */
1.47 +static unsigned ec_laplace_get_freq1(unsigned fs0, int decay)
1.48 +{
1.49 + unsigned ft;
1.50 + ft = 32768 - LAPLACE_MINP*(2*LAPLACE_NMIN) - fs0;
1.51 + return ft*(opus_int32)(16384-decay)>>15;
1.52 +}
1.53 +
1.54 +void ec_laplace_encode(ec_enc *enc, int *value, unsigned fs, int decay)
1.55 +{
1.56 + unsigned fl;
1.57 + int val = *value;
1.58 + fl = 0;
1.59 + if (val)
1.60 + {
1.61 + int s;
1.62 + int i;
1.63 + s = -(val<0);
1.64 + val = (val+s)^s;
1.65 + fl = fs;
1.66 + fs = ec_laplace_get_freq1(fs, decay);
1.67 + /* Search the decaying part of the PDF.*/
1.68 + for (i=1; fs > 0 && i < val; i++)
1.69 + {
1.70 + fs *= 2;
1.71 + fl += fs+2*LAPLACE_MINP;
1.72 + fs = (fs*(opus_int32)decay)>>15;
1.73 + }
1.74 + /* Everything beyond that has probability LAPLACE_MINP. */
1.75 + if (!fs)
1.76 + {
1.77 + int di;
1.78 + int ndi_max;
1.79 + ndi_max = (32768-fl+LAPLACE_MINP-1)>>LAPLACE_LOG_MINP;
1.80 + ndi_max = (ndi_max-s)>>1;
1.81 + di = IMIN(val - i, ndi_max - 1);
1.82 + fl += (2*di+1+s)*LAPLACE_MINP;
1.83 + fs = IMIN(LAPLACE_MINP, 32768-fl);
1.84 + *value = (i+di+s)^s;
1.85 + }
1.86 + else
1.87 + {
1.88 + fs += LAPLACE_MINP;
1.89 + fl += fs&~s;
1.90 + }
1.91 + celt_assert(fl+fs<=32768);
1.92 + celt_assert(fs>0);
1.93 + }
1.94 + ec_encode_bin(enc, fl, fl+fs, 15);
1.95 +}
1.96 +
1.97 +int ec_laplace_decode(ec_dec *dec, unsigned fs, int decay)
1.98 +{
1.99 + int val=0;
1.100 + unsigned fl;
1.101 + unsigned fm;
1.102 + fm = ec_decode_bin(dec, 15);
1.103 + fl = 0;
1.104 + if (fm >= fs)
1.105 + {
1.106 + val++;
1.107 + fl = fs;
1.108 + fs = ec_laplace_get_freq1(fs, decay)+LAPLACE_MINP;
1.109 + /* Search the decaying part of the PDF.*/
1.110 + while(fs > LAPLACE_MINP && fm >= fl+2*fs)
1.111 + {
1.112 + fs *= 2;
1.113 + fl += fs;
1.114 + fs = ((fs-2*LAPLACE_MINP)*(opus_int32)decay)>>15;
1.115 + fs += LAPLACE_MINP;
1.116 + val++;
1.117 + }
1.118 + /* Everything beyond that has probability LAPLACE_MINP. */
1.119 + if (fs <= LAPLACE_MINP)
1.120 + {
1.121 + int di;
1.122 + di = (fm-fl)>>(LAPLACE_LOG_MINP+1);
1.123 + val += di;
1.124 + fl += 2*di*LAPLACE_MINP;
1.125 + }
1.126 + if (fm < fl+fs)
1.127 + val = -val;
1.128 + else
1.129 + fl += fs;
1.130 + }
1.131 + celt_assert(fl<32768);
1.132 + celt_assert(fs>0);
1.133 + celt_assert(fl<=fm);
1.134 + celt_assert(fm<IMIN(fl+fs,32768));
1.135 + ec_dec_update(dec, fl, IMIN(fl+fs,32768), 32768);
1.136 + return val;
1.137 +}
