media/libopus/celt/laplace.c@b8a032363ba2 (annotated)
media/libopus/celt/laplace.c
Thu, 22 Jan 2015 13:21:57 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 22 Jan 2015 13:21:57 +0100
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
- permissions
- -rw-r--r--
Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6
| michael@0 | 1 | /* Copyright (c) 2007 CSIRO |
| michael@0 | 2 | Copyright (c) 2007-2009 Xiph.Org Foundation |
| michael@0 | 3 | Written by Jean-Marc Valin */ |
| michael@0 | 4 | /* |
| michael@0 | 5 | Redistribution and use in source and binary forms, with or without |
| michael@0 | 6 | modification, are permitted provided that the following conditions |
| michael@0 | 7 | are met: |
| michael@0 | 8 | |
| michael@0 | 9 | - Redistributions of source code must retain the above copyright |
| michael@0 | 10 | notice, this list of conditions and the following disclaimer. |
| michael@0 | 11 | |
| michael@0 | 12 | - Redistributions in binary form must reproduce the above copyright |
| michael@0 | 13 | notice, this list of conditions and the following disclaimer in the |
| michael@0 | 14 | documentation and/or other materials provided with the distribution. |
| michael@0 | 15 | |
| michael@0 | 16 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| michael@0 | 17 | ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| michael@0 | 18 | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| michael@0 | 19 | A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER |
| michael@0 | 20 | OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| michael@0 | 21 | EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| michael@0 | 22 | PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| michael@0 | 23 | PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| michael@0 | 24 | LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| michael@0 | 25 | NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| michael@0 | 26 | SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| michael@0 | 27 | */ |
| michael@0 | 28 | |
| michael@0 | 29 | #ifdef HAVE_CONFIG_H |
| michael@0 | 30 | #include "config.h" |
| michael@0 | 31 | #endif |
| michael@0 | 32 | |
| michael@0 | 33 | #include "laplace.h" |
| michael@0 | 34 | #include "mathops.h" |
| michael@0 | 35 | |
| michael@0 | 36 | /* The minimum probability of an energy delta (out of 32768). */ |
| michael@0 | 37 | #define LAPLACE_LOG_MINP (0) |
| michael@0 | 38 | #define LAPLACE_MINP (1<<LAPLACE_LOG_MINP) |
| michael@0 | 39 | /* The minimum number of guaranteed representable energy deltas (in one |
| michael@0 | 40 | direction). */ |
| michael@0 | 41 | #define LAPLACE_NMIN (16) |
| michael@0 | 42 | |
| michael@0 | 43 | /* When called, decay is positive and at most 11456. */ |
| michael@0 | 44 | static unsigned ec_laplace_get_freq1(unsigned fs0, int decay) |
| michael@0 | 45 | { |
| michael@0 | 46 | unsigned ft; |
| michael@0 | 47 | ft = 32768 - LAPLACE_MINP*(2*LAPLACE_NMIN) - fs0; |
| michael@0 | 48 | return ft*(opus_int32)(16384-decay)>>15; |
| michael@0 | 49 | } |
| michael@0 | 50 | |
| michael@0 | 51 | void ec_laplace_encode(ec_enc *enc, int *value, unsigned fs, int decay) |
| michael@0 | 52 | { |
| michael@0 | 53 | unsigned fl; |
| michael@0 | 54 | int val = *value; |
| michael@0 | 55 | fl = 0; |
| michael@0 | 56 | if (val) |
| michael@0 | 57 | { |
| michael@0 | 58 | int s; |
| michael@0 | 59 | int i; |
| michael@0 | 60 | s = -(val<0); |
| michael@0 | 61 | val = (val+s)^s; |
| michael@0 | 62 | fl = fs; |
| michael@0 | 63 | fs = ec_laplace_get_freq1(fs, decay); |
| michael@0 | 64 | /* Search the decaying part of the PDF.*/ |
| michael@0 | 65 | for (i=1; fs > 0 && i < val; i++) |
| michael@0 | 66 | { |
| michael@0 | 67 | fs *= 2; |
| michael@0 | 68 | fl += fs+2*LAPLACE_MINP; |
| michael@0 | 69 | fs = (fs*(opus_int32)decay)>>15; |
| michael@0 | 70 | } |
| michael@0 | 71 | /* Everything beyond that has probability LAPLACE_MINP. */ |
| michael@0 | 72 | if (!fs) |
| michael@0 | 73 | { |
| michael@0 | 74 | int di; |
| michael@0 | 75 | int ndi_max; |
| michael@0 | 76 | ndi_max = (32768-fl+LAPLACE_MINP-1)>>LAPLACE_LOG_MINP; |
| michael@0 | 77 | ndi_max = (ndi_max-s)>>1; |
| michael@0 | 78 | di = IMIN(val - i, ndi_max - 1); |
| michael@0 | 79 | fl += (2*di+1+s)*LAPLACE_MINP; |
| michael@0 | 80 | fs = IMIN(LAPLACE_MINP, 32768-fl); |
| michael@0 | 81 | *value = (i+di+s)^s; |
| michael@0 | 82 | } |
| michael@0 | 83 | else |
| michael@0 | 84 | { |
| michael@0 | 85 | fs += LAPLACE_MINP; |
| michael@0 | 86 | fl += fs&~s; |
| michael@0 | 87 | } |
| michael@0 | 88 | celt_assert(fl+fs<=32768); |
| michael@0 | 89 | celt_assert(fs>0); |
| michael@0 | 90 | } |
| michael@0 | 91 | ec_encode_bin(enc, fl, fl+fs, 15); |
| michael@0 | 92 | } |
| michael@0 | 93 | |
| michael@0 | 94 | int ec_laplace_decode(ec_dec *dec, unsigned fs, int decay) |
| michael@0 | 95 | { |
| michael@0 | 96 | int val=0; |
| michael@0 | 97 | unsigned fl; |
| michael@0 | 98 | unsigned fm; |
| michael@0 | 99 | fm = ec_decode_bin(dec, 15); |
| michael@0 | 100 | fl = 0; |
| michael@0 | 101 | if (fm >= fs) |
| michael@0 | 102 | { |
| michael@0 | 103 | val++; |
| michael@0 | 104 | fl = fs; |
| michael@0 | 105 | fs = ec_laplace_get_freq1(fs, decay)+LAPLACE_MINP; |
| michael@0 | 106 | /* Search the decaying part of the PDF.*/ |
| michael@0 | 107 | while(fs > LAPLACE_MINP && fm >= fl+2*fs) |
| michael@0 | 108 | { |
| michael@0 | 109 | fs *= 2; |
| michael@0 | 110 | fl += fs; |
| michael@0 | 111 | fs = ((fs-2*LAPLACE_MINP)*(opus_int32)decay)>>15; |
| michael@0 | 112 | fs += LAPLACE_MINP; |
| michael@0 | 113 | val++; |
| michael@0 | 114 | } |
| michael@0 | 115 | /* Everything beyond that has probability LAPLACE_MINP. */ |
| michael@0 | 116 | if (fs <= LAPLACE_MINP) |
| michael@0 | 117 | { |
| michael@0 | 118 | int di; |
| michael@0 | 119 | di = (fm-fl)>>(LAPLACE_LOG_MINP+1); |
| michael@0 | 120 | val += di; |
| michael@0 | 121 | fl += 2*di*LAPLACE_MINP; |
| michael@0 | 122 | } |
| michael@0 | 123 | if (fm < fl+fs) |
| michael@0 | 124 | val = -val; |
| michael@0 | 125 | else |
| michael@0 | 126 | fl += fs; |
| michael@0 | 127 | } |
| michael@0 | 128 | celt_assert(fl<32768); |
| michael@0 | 129 | celt_assert(fs>0); |
| michael@0 | 130 | celt_assert(fl<=fm); |
| michael@0 | 131 | celt_assert(fm<IMIN(fl+fs,32768)); |
| michael@0 | 132 | ec_dec_update(dec, fl, IMIN(fl+fs,32768), 32768); |
| michael@0 | 133 | return val; |
| michael@0 | 134 | } |
