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annotate src/opus-1.3/celt/laplace.c @ 69:7aeed7906520

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Add Opus sources and macOS builds
author Chris Cannam
date Wed, 23 Jan 2019 13:48:08 +0000
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Chris@69 1 /* Copyright (c) 2007 CSIRO
Chris@69 2 Copyright (c) 2007-2009 Xiph.Org Foundation
Chris@69 3 Written by Jean-Marc Valin */
Chris@69 4 /*
Chris@69 5 Redistribution and use in source and binary forms, with or without
Chris@69 6 modification, are permitted provided that the following conditions
Chris@69 7 are met:
Chris@69 8
Chris@69 9 - Redistributions of source code must retain the above copyright
Chris@69 10 notice, this list of conditions and the following disclaimer.
Chris@69 11
Chris@69 12 - Redistributions in binary form must reproduce the above copyright
Chris@69 13 notice, this list of conditions and the following disclaimer in the
Chris@69 14 documentation and/or other materials provided with the distribution.
Chris@69 15
Chris@69 16 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
Chris@69 17 ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
Chris@69 18 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
Chris@69 19 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
Chris@69 20 OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
Chris@69 21 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
Chris@69 22 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
Chris@69 23 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
Chris@69 24 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
Chris@69 25 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
Chris@69 26 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Chris@69 27 */
Chris@69 28
Chris@69 29 #ifdef HAVE_CONFIG_H
Chris@69 30 #include "config.h"
Chris@69 31 #endif
Chris@69 32
Chris@69 33 #include "laplace.h"
Chris@69 34 #include "mathops.h"
Chris@69 35
Chris@69 36 /* The minimum probability of an energy delta (out of 32768). */
Chris@69 37 #define LAPLACE_LOG_MINP (0)
Chris@69 38 #define LAPLACE_MINP (1<<LAPLACE_LOG_MINP)
Chris@69 39 /* The minimum number of guaranteed representable energy deltas (in one
Chris@69 40 direction). */
Chris@69 41 #define LAPLACE_NMIN (16)
Chris@69 42
Chris@69 43 /* When called, decay is positive and at most 11456. */
Chris@69 44 static unsigned ec_laplace_get_freq1(unsigned fs0, int decay)
Chris@69 45 {
Chris@69 46 unsigned ft;
Chris@69 47 ft = 32768 - LAPLACE_MINP*(2*LAPLACE_NMIN) - fs0;
Chris@69 48 return ft*(opus_int32)(16384-decay)>>15;
Chris@69 49 }
Chris@69 50
Chris@69 51 void ec_laplace_encode(ec_enc *enc, int *value, unsigned fs, int decay)
Chris@69 52 {
Chris@69 53 unsigned fl;
Chris@69 54 int val = *value;
Chris@69 55 fl = 0;
Chris@69 56 if (val)
Chris@69 57 {
Chris@69 58 int s;
Chris@69 59 int i;
Chris@69 60 s = -(val<0);
Chris@69 61 val = (val+s)^s;
Chris@69 62 fl = fs;
Chris@69 63 fs = ec_laplace_get_freq1(fs, decay);
Chris@69 64 /* Search the decaying part of the PDF.*/
Chris@69 65 for (i=1; fs > 0 && i < val; i++)
Chris@69 66 {
Chris@69 67 fs *= 2;
Chris@69 68 fl += fs+2*LAPLACE_MINP;
Chris@69 69 fs = (fs*(opus_int32)decay)>>15;
Chris@69 70 }
Chris@69 71 /* Everything beyond that has probability LAPLACE_MINP. */
Chris@69 72 if (!fs)
Chris@69 73 {
Chris@69 74 int di;
Chris@69 75 int ndi_max;
Chris@69 76 ndi_max = (32768-fl+LAPLACE_MINP-1)>>LAPLACE_LOG_MINP;
Chris@69 77 ndi_max = (ndi_max-s)>>1;
Chris@69 78 di = IMIN(val - i, ndi_max - 1);
Chris@69 79 fl += (2*di+1+s)*LAPLACE_MINP;
Chris@69 80 fs = IMIN(LAPLACE_MINP, 32768-fl);
Chris@69 81 *value = (i+di+s)^s;
Chris@69 82 }
Chris@69 83 else
Chris@69 84 {
Chris@69 85 fs += LAPLACE_MINP;
Chris@69 86 fl += fs&~s;
Chris@69 87 }
Chris@69 88 celt_assert(fl+fs<=32768);
Chris@69 89 celt_assert(fs>0);
Chris@69 90 }
Chris@69 91 ec_encode_bin(enc, fl, fl+fs, 15);
Chris@69 92 }
Chris@69 93
Chris@69 94 int ec_laplace_decode(ec_dec *dec, unsigned fs, int decay)
Chris@69 95 {
Chris@69 96 int val=0;
Chris@69 97 unsigned fl;
Chris@69 98 unsigned fm;
Chris@69 99 fm = ec_decode_bin(dec, 15);
Chris@69 100 fl = 0;
Chris@69 101 if (fm >= fs)
Chris@69 102 {
Chris@69 103 val++;
Chris@69 104 fl = fs;
Chris@69 105 fs = ec_laplace_get_freq1(fs, decay)+LAPLACE_MINP;
Chris@69 106 /* Search the decaying part of the PDF.*/
Chris@69 107 while(fs > LAPLACE_MINP && fm >= fl+2*fs)
Chris@69 108 {
Chris@69 109 fs *= 2;
Chris@69 110 fl += fs;
Chris@69 111 fs = ((fs-2*LAPLACE_MINP)*(opus_int32)decay)>>15;
Chris@69 112 fs += LAPLACE_MINP;
Chris@69 113 val++;
Chris@69 114 }
Chris@69 115 /* Everything beyond that has probability LAPLACE_MINP. */
Chris@69 116 if (fs <= LAPLACE_MINP)
Chris@69 117 {
Chris@69 118 int di;
Chris@69 119 di = (fm-fl)>>(LAPLACE_LOG_MINP+1);
Chris@69 120 val += di;
Chris@69 121 fl += 2*di*LAPLACE_MINP;
Chris@69 122 }
Chris@69 123 if (fm < fl+fs)
Chris@69 124 val = -val;
Chris@69 125 else
Chris@69 126 fl += fs;
Chris@69 127 }
Chris@69 128 celt_assert(fl<32768);
Chris@69 129 celt_assert(fs>0);
Chris@69 130 celt_assert(fl<=fm);
Chris@69 131 celt_assert(fm<IMIN(fl+fs,32768));
Chris@69 132 ec_dec_update(dec, fl, IMIN(fl+fs,32768), 32768);
Chris@69 133 return val;
Chris@69 134 }