xref: /aosp_15_r20/external/libopus/celt/laplace.c (revision a58d3d2adb790c104798cd88c8a3aff4fa8b82cc)
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. */
ec_laplace_get_freq1(unsigned fs0,int decay)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 
ec_laplace_encode(ec_enc * enc,int * value,unsigned fs,int decay)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 
ec_laplace_decode(ec_dec * dec,unsigned fs,int decay)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 }
135 
ec_laplace_encode_p0(ec_enc * enc,int value,opus_uint16 p0,opus_uint16 decay)136 void ec_laplace_encode_p0(ec_enc *enc, int value, opus_uint16 p0, opus_uint16 decay)
137 {
138    int s;
139    opus_uint16 sign_icdf[3];
140    sign_icdf[0] = 32768-p0;
141    sign_icdf[1] = sign_icdf[0]/2;
142    sign_icdf[2] = 0;
143    s = value == 0 ? 0 : (value > 0 ? 1 : 2);
144    ec_enc_icdf16(enc, s, sign_icdf, 15);
145    value = abs(value);
146    if (value)
147    {
148       int i;
149       opus_uint16 icdf[8];
150       icdf[0] = IMAX(7, decay);
151       for (i=1;i<7;i++)
152       {
153          icdf[i] = IMAX(7-i, (icdf[i-1] * (opus_int32)decay) >> 15);
154       }
155       icdf[7] = 0;
156       value--;
157       do {
158          ec_enc_icdf16(enc, IMIN(value, 7), icdf, 15);
159          value -= 7;
160       } while (value >= 0);
161    }
162 }
163 
ec_laplace_decode_p0(ec_dec * dec,opus_uint16 p0,opus_uint16 decay)164 int ec_laplace_decode_p0(ec_dec *dec, opus_uint16 p0, opus_uint16 decay)
165 {
166    int s;
167    int value;
168    opus_uint16 sign_icdf[3];
169    sign_icdf[0] = 32768-p0;
170    sign_icdf[1] = sign_icdf[0]/2;
171    sign_icdf[2] = 0;
172    s = ec_dec_icdf16(dec, sign_icdf, 15);
173    if (s==2) s = -1;
174    if (s != 0)
175    {
176       int i;
177       int v;
178       opus_uint16 icdf[8];
179       icdf[0] = IMAX(7, decay);
180       for (i=1;i<7;i++)
181       {
182          icdf[i] = IMAX(7-i, (icdf[i-1] * (opus_int32)decay) >> 15);
183       }
184       icdf[7] = 0;
185       value = 1;
186       do {
187          v = ec_dec_icdf16(dec, icdf, 15);
188          value += v;
189       } while (v == 7);
190       return s*value;
191    } else return 0;
192 }
193 
194 #if 0
195 
196 #include <stdio.h>
197 #define NB_VALS 10
198 #define DATA_SIZE 10000
199 int main() {
200    ec_enc enc;
201    ec_dec dec;
202    unsigned char *ptr;
203    int i;
204    int decay, p0;
205    int val[NB_VALS] = {6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
206    /*for (i=0;i<NB_VALS;i++) {
207       val[i] = -log(rand()/(float)RAND_MAX);
208       if (rand()%2) val[i] = -val[i];
209    }*/
210    p0 = 16000;
211    decay = 16000;
212    ptr = (unsigned char *)malloc(DATA_SIZE);
213    ec_enc_init(&enc,ptr,DATA_SIZE);
214    for (i=0;i<NB_VALS;i++) {
215       printf("%d ", val[i]);
216    }
217    printf("\n");
218    for (i=0;i<NB_VALS;i++) {
219       ec_laplace_encode_p0(&enc, val[i], p0, decay);
220    }
221 
222    ec_enc_done(&enc);
223 
224    ec_dec_init(&dec,ec_get_buffer(&enc),ec_range_bytes(&enc));
225 
226    for (i=0;i<NB_VALS;i++) {
227       val[i] = ec_laplace_decode_p0(&dec, p0, decay);
228    }
229    for (i=0;i<NB_VALS;i++) {
230       printf("%d ", val[i]);
231    }
232    printf("\n");
233 }
234 
235 #endif
236