1*a58d3d2aSXin Li /***********************************************************************
2*a58d3d2aSXin Li Copyright (c) 2006-2011, Skype Limited. All rights reserved.
3*a58d3d2aSXin Li Redistribution and use in source and binary forms, with or without
4*a58d3d2aSXin Li modification, are permitted provided that the following conditions
5*a58d3d2aSXin Li are met:
6*a58d3d2aSXin Li - Redistributions of source code must retain the above copyright notice,
7*a58d3d2aSXin Li this list of conditions and the following disclaimer.
8*a58d3d2aSXin Li - Redistributions in binary form must reproduce the above copyright
9*a58d3d2aSXin Li notice, this list of conditions and the following disclaimer in the
10*a58d3d2aSXin Li documentation and/or other materials provided with the distribution.
11*a58d3d2aSXin Li - Neither the name of Internet Society, IETF or IETF Trust, nor the
12*a58d3d2aSXin Li names of specific contributors, may be used to endorse or promote
13*a58d3d2aSXin Li products derived from this software without specific prior written
14*a58d3d2aSXin Li permission.
15*a58d3d2aSXin Li THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16*a58d3d2aSXin Li AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17*a58d3d2aSXin Li IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18*a58d3d2aSXin Li ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
19*a58d3d2aSXin Li LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
20*a58d3d2aSXin Li CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
21*a58d3d2aSXin Li SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22*a58d3d2aSXin Li INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23*a58d3d2aSXin Li CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
24*a58d3d2aSXin Li ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
25*a58d3d2aSXin Li POSSIBILITY OF SUCH DAMAGE.
26*a58d3d2aSXin Li ***********************************************************************/
27*a58d3d2aSXin Li
28*a58d3d2aSXin Li #ifdef HAVE_CONFIG_H
29*a58d3d2aSXin Li #include "config.h"
30*a58d3d2aSXin Li #endif
31*a58d3d2aSXin Li
32*a58d3d2aSXin Li /* Approximate sigmoid function */
33*a58d3d2aSXin Li
34*a58d3d2aSXin Li #include "SigProc_FIX.h"
35*a58d3d2aSXin Li
36*a58d3d2aSXin Li /* fprintf(1, '%d, ', round(1024 * ([1 ./ (1 + exp(-(1:5))), 1] - 1 ./ (1 + exp(-(0:5)))))); */
37*a58d3d2aSXin Li static const opus_int32 sigm_LUT_slope_Q10[ 6 ] = {
38*a58d3d2aSXin Li 237, 153, 73, 30, 12, 7
39*a58d3d2aSXin Li };
40*a58d3d2aSXin Li /* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp(-(0:5))))); */
41*a58d3d2aSXin Li static const opus_int32 sigm_LUT_pos_Q15[ 6 ] = {
42*a58d3d2aSXin Li 16384, 23955, 28861, 31213, 32178, 32548
43*a58d3d2aSXin Li };
44*a58d3d2aSXin Li /* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp((0:5))))); */
45*a58d3d2aSXin Li static const opus_int32 sigm_LUT_neg_Q15[ 6 ] = {
46*a58d3d2aSXin Li 16384, 8812, 3906, 1554, 589, 219
47*a58d3d2aSXin Li };
48*a58d3d2aSXin Li
silk_sigm_Q15(opus_int in_Q5)49*a58d3d2aSXin Li opus_int silk_sigm_Q15(
50*a58d3d2aSXin Li opus_int in_Q5 /* I */
51*a58d3d2aSXin Li )
52*a58d3d2aSXin Li {
53*a58d3d2aSXin Li opus_int ind;
54*a58d3d2aSXin Li
55*a58d3d2aSXin Li if( in_Q5 < 0 ) {
56*a58d3d2aSXin Li /* Negative input */
57*a58d3d2aSXin Li in_Q5 = -in_Q5;
58*a58d3d2aSXin Li if( in_Q5 >= 6 * 32 ) {
59*a58d3d2aSXin Li return 0; /* Clip */
60*a58d3d2aSXin Li } else {
61*a58d3d2aSXin Li /* Linear interpolation of look up table */
62*a58d3d2aSXin Li ind = silk_RSHIFT( in_Q5, 5 );
63*a58d3d2aSXin Li return( sigm_LUT_neg_Q15[ ind ] - silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) );
64*a58d3d2aSXin Li }
65*a58d3d2aSXin Li } else {
66*a58d3d2aSXin Li /* Positive input */
67*a58d3d2aSXin Li if( in_Q5 >= 6 * 32 ) {
68*a58d3d2aSXin Li return 32767; /* clip */
69*a58d3d2aSXin Li } else {
70*a58d3d2aSXin Li /* Linear interpolation of look up table */
71*a58d3d2aSXin Li ind = silk_RSHIFT( in_Q5, 5 );
72*a58d3d2aSXin Li return( sigm_LUT_pos_Q15[ ind ] + silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) );
73*a58d3d2aSXin Li }
74*a58d3d2aSXin Li }
75*a58d3d2aSXin Li }
76*a58d3d2aSXin Li
77