77 lines
3.1 KiB
C
77 lines
3.1 KiB
C
/***********************************************************************
|
|
Copyright (c) 2006-2011, Skype Limited. All rights reserved.
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, are permitted provided that the following conditions
|
|
are met:
|
|
- Redistributions of source code must retain the above copyright notice,
|
|
this list of conditions and the following disclaimer.
|
|
- Redistributions in binary form must reproduce the above copyright
|
|
notice, this list of conditions and the following disclaimer in the
|
|
documentation and/or other materials provided with the distribution.
|
|
- Neither the name of Internet Society, IETF or IETF Trust, nor the
|
|
names of specific contributors, may be used to endorse or promote
|
|
products derived from this software without specific prior written
|
|
permission.
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
POSSIBILITY OF SUCH DAMAGE.
|
|
***********************************************************************/
|
|
|
|
#ifdef OPUS_ENABLED
|
|
#include "opus/opus_config.h"
|
|
#endif
|
|
|
|
/* Approximate sigmoid function */
|
|
|
|
#include "opus/silk/SigProc_FIX.h"
|
|
|
|
/* fprintf(1, '%d, ', round(1024 * ([1 ./ (1 + exp(-(1:5))), 1] - 1 ./ (1 + exp(-(0:5)))))); */
|
|
static const opus_int32 sigm_LUT_slope_Q10[ 6 ] = {
|
|
237, 153, 73, 30, 12, 7
|
|
};
|
|
/* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp(-(0:5))))); */
|
|
static const opus_int32 sigm_LUT_pos_Q15[ 6 ] = {
|
|
16384, 23955, 28861, 31213, 32178, 32548
|
|
};
|
|
/* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp((0:5))))); */
|
|
static const opus_int32 sigm_LUT_neg_Q15[ 6 ] = {
|
|
16384, 8812, 3906, 1554, 589, 219
|
|
};
|
|
|
|
opus_int silk_sigm_Q15(
|
|
opus_int in_Q5 /* I */
|
|
)
|
|
{
|
|
opus_int ind;
|
|
|
|
if( in_Q5 < 0 ) {
|
|
/* Negative input */
|
|
in_Q5 = -in_Q5;
|
|
if( in_Q5 >= 6 * 32 ) {
|
|
return 0; /* Clip */
|
|
} else {
|
|
/* Linear interpolation of look up table */
|
|
ind = silk_RSHIFT( in_Q5, 5 );
|
|
return( sigm_LUT_neg_Q15[ ind ] - silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) );
|
|
}
|
|
} else {
|
|
/* Positive input */
|
|
if( in_Q5 >= 6 * 32 ) {
|
|
return 32767; /* clip */
|
|
} else {
|
|
/* Linear interpolation of look up table */
|
|
ind = silk_RSHIFT( in_Q5, 5 );
|
|
return( sigm_LUT_pos_Q15[ ind ] + silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) );
|
|
}
|
|
}
|
|
}
|
|
|