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