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comparison: media/libopus/celt/laplace.c
media/libopus/celt/laplace.c
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:2afb5ecbf323 |
|---|---|
| 1 /* Copyright (c) 2007 CSIRO | |
| 2 Copyright (c) 2007-2009 Xiph.Org Foundation | |
| 3 Written by Jean-Marc Valin */ | |
| 4 /* | |
| 5 Redistribution and use in source and binary forms, with or without | |
| 6 modification, are permitted provided that the following conditions | |
| 7 are met: | |
| 8 | |
| 9 - Redistributions of source code must retain the above copyright | |
| 10 notice, this list of conditions and the following disclaimer. | |
| 11 | |
| 12 - Redistributions in binary form must reproduce the above copyright | |
| 13 notice, this list of conditions and the following disclaimer in the | |
| 14 documentation and/or other materials provided with the distribution. | |
| 15 | |
| 16 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 17 ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 18 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| 19 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER | |
| 20 OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, | |
| 21 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | |
| 22 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | |
| 23 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | |
| 24 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING | |
| 25 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | |
| 26 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 27 */ | |
| 28 | |
| 29 #ifdef HAVE_CONFIG_H | |
| 30 #include "config.h" | |
| 31 #endif | |
| 32 | |
| 33 #include "laplace.h" | |
| 34 #include "mathops.h" | |
| 35 | |
| 36 /* The minimum probability of an energy delta (out of 32768). */ | |
| 37 #define LAPLACE_LOG_MINP (0) | |
| 38 #define LAPLACE_MINP (1<<LAPLACE_LOG_MINP) | |
| 39 /* The minimum number of guaranteed representable energy deltas (in one | |
| 40 direction). */ | |
| 41 #define LAPLACE_NMIN (16) | |
| 42 | |
| 43 /* When called, decay is positive and at most 11456. */ | |
| 44 static unsigned ec_laplace_get_freq1(unsigned fs0, int decay) | |
| 45 { | |
| 46 unsigned ft; | |
| 47 ft = 32768 - LAPLACE_MINP*(2*LAPLACE_NMIN) - fs0; | |
| 48 return ft*(opus_int32)(16384-decay)>>15; | |
| 49 } | |
| 50 | |
| 51 void ec_laplace_encode(ec_enc *enc, int *value, unsigned fs, int decay) | |
| 52 { | |
| 53 unsigned fl; | |
| 54 int val = *value; | |
| 55 fl = 0; | |
| 56 if (val) | |
| 57 { | |
| 58 int s; | |
| 59 int i; | |
| 60 s = -(val<0); | |
| 61 val = (val+s)^s; | |
| 62 fl = fs; | |
| 63 fs = ec_laplace_get_freq1(fs, decay); | |
| 64 /* Search the decaying part of the PDF.*/ | |
| 65 for (i=1; fs > 0 && i < val; i++) | |
| 66 { | |
| 67 fs *= 2; | |
| 68 fl += fs+2*LAPLACE_MINP; | |
| 69 fs = (fs*(opus_int32)decay)>>15; | |
| 70 } | |
| 71 /* Everything beyond that has probability LAPLACE_MINP. */ | |
| 72 if (!fs) | |
| 73 { | |
| 74 int di; | |
| 75 int ndi_max; | |
| 76 ndi_max = (32768-fl+LAPLACE_MINP-1)>>LAPLACE_LOG_MINP; | |
| 77 ndi_max = (ndi_max-s)>>1; | |
| 78 di = IMIN(val - i, ndi_max - 1); | |
| 79 fl += (2*di+1+s)*LAPLACE_MINP; | |
| 80 fs = IMIN(LAPLACE_MINP, 32768-fl); | |
| 81 *value = (i+di+s)^s; | |
| 82 } | |
| 83 else | |
| 84 { | |
| 85 fs += LAPLACE_MINP; | |
| 86 fl += fs&~s; | |
| 87 } | |
| 88 celt_assert(fl+fs<=32768); | |
| 89 celt_assert(fs>0); | |
| 90 } | |
| 91 ec_encode_bin(enc, fl, fl+fs, 15); | |
| 92 } | |
| 93 | |
| 94 int ec_laplace_decode(ec_dec *dec, unsigned fs, int decay) | |
| 95 { | |
| 96 int val=0; | |
| 97 unsigned fl; | |
| 98 unsigned fm; | |
| 99 fm = ec_decode_bin(dec, 15); | |
| 100 fl = 0; | |
| 101 if (fm >= fs) | |
| 102 { | |
| 103 val++; | |
| 104 fl = fs; | |
| 105 fs = ec_laplace_get_freq1(fs, decay)+LAPLACE_MINP; | |
| 106 /* Search the decaying part of the PDF.*/ | |
| 107 while(fs > LAPLACE_MINP && fm >= fl+2*fs) | |
| 108 { | |
| 109 fs *= 2; | |
| 110 fl += fs; | |
| 111 fs = ((fs-2*LAPLACE_MINP)*(opus_int32)decay)>>15; | |
| 112 fs += LAPLACE_MINP; | |
| 113 val++; | |
| 114 } | |
| 115 /* Everything beyond that has probability LAPLACE_MINP. */ | |
| 116 if (fs <= LAPLACE_MINP) | |
| 117 { | |
| 118 int di; | |
| 119 di = (fm-fl)>>(LAPLACE_LOG_MINP+1); | |
| 120 val += di; | |
| 121 fl += 2*di*LAPLACE_MINP; | |
| 122 } | |
| 123 if (fm < fl+fs) | |
| 124 val = -val; | |
| 125 else | |
| 126 fl += fs; | |
| 127 } | |
| 128 celt_assert(fl<32768); | |
| 129 celt_assert(fs>0); | |
| 130 celt_assert(fl<=fm); | |
| 131 celt_assert(fm<IMIN(fl+fs,32768)); | |
| 132 ec_dec_update(dec, fl, IMIN(fl+fs,32768), 32768); | |
| 133 return val; | |
| 134 } |
