1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/sigm_Q15.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,76 @@
1.4 +/***********************************************************************
1.5 +Copyright (c) 2006-2011, Skype Limited. All rights reserved.
1.6 +Redistribution and use in source and binary forms, with or without
1.7 +modification, are permitted provided that the following conditions
1.8 +are met:
1.9 +- Redistributions of source code must retain the above copyright notice,
1.10 +this list of conditions and the following disclaimer.
1.11 +- Redistributions in binary form must reproduce the above copyright
1.12 +notice, this list of conditions and the following disclaimer in the
1.13 +documentation and/or other materials provided with the distribution.
1.14 +- Neither the name of Internet Society, IETF or IETF Trust, nor the
1.15 +names of specific contributors, may be used to endorse or promote
1.16 +products derived from this software without specific prior written
1.17 +permission.
1.18 +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.19 +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.20 +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.21 +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
1.22 +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.23 +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.24 +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.25 +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.26 +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.27 +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.28 +POSSIBILITY OF SUCH DAMAGE.
1.29 +***********************************************************************/
1.30 +
1.31 +#ifdef HAVE_CONFIG_H
1.32 +#include "config.h"
1.33 +#endif
1.34 +
1.35 +/* Approximate sigmoid function */
1.36 +
1.37 +#include "SigProc_FIX.h"
1.38 +
1.39 +/* fprintf(1, '%d, ', round(1024 * ([1 ./ (1 + exp(-(1:5))), 1] - 1 ./ (1 + exp(-(0:5)))))); */
1.40 +static const opus_int32 sigm_LUT_slope_Q10[ 6 ] = {
1.41 + 237, 153, 73, 30, 12, 7
1.42 +};
1.43 +/* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp(-(0:5))))); */
1.44 +static const opus_int32 sigm_LUT_pos_Q15[ 6 ] = {
1.45 + 16384, 23955, 28861, 31213, 32178, 32548
1.46 +};
1.47 +/* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp((0:5))))); */
1.48 +static const opus_int32 sigm_LUT_neg_Q15[ 6 ] = {
1.49 + 16384, 8812, 3906, 1554, 589, 219
1.50 +};
1.51 +
1.52 +opus_int silk_sigm_Q15(
1.53 + opus_int in_Q5 /* I */
1.54 +)
1.55 +{
1.56 + opus_int ind;
1.57 +
1.58 + if( in_Q5 < 0 ) {
1.59 + /* Negative input */
1.60 + in_Q5 = -in_Q5;
1.61 + if( in_Q5 >= 6 * 32 ) {
1.62 + return 0; /* Clip */
1.63 + } else {
1.64 + /* Linear interpolation of look up table */
1.65 + ind = silk_RSHIFT( in_Q5, 5 );
1.66 + return( sigm_LUT_neg_Q15[ ind ] - silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) );
1.67 + }
1.68 + } else {
1.69 + /* Positive input */
1.70 + if( in_Q5 >= 6 * 32 ) {
1.71 + return 32767; /* clip */
1.72 + } else {
1.73 + /* Linear interpolation of look up table */
1.74 + ind = silk_RSHIFT( in_Q5, 5 );
1.75 + return( sigm_LUT_pos_Q15[ ind ] + silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) );
1.76 + }
1.77 + }
1.78 +}
1.79 +
