media/libopus/silk/sigm_Q15.c@b8a032363ba2 (annotated)
media/libopus/silk/sigm_Q15.c
Thu, 22 Jan 2015 13:21:57 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 22 Jan 2015 13:21:57 +0100
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
- permissions
- -rw-r--r--
Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6
| michael@0 | 1 | /*********************************************************************** |
| michael@0 | 2 | Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
| michael@0 | 3 | Redistribution and use in source and binary forms, with or without |
| michael@0 | 4 | modification, are permitted provided that the following conditions |
| michael@0 | 5 | are met: |
| michael@0 | 6 | - Redistributions of source code must retain the above copyright notice, |
| michael@0 | 7 | this list of conditions and the following disclaimer. |
| michael@0 | 8 | - Redistributions in binary form must reproduce the above copyright |
| michael@0 | 9 | notice, this list of conditions and the following disclaimer in the |
| michael@0 | 10 | documentation and/or other materials provided with the distribution. |
| michael@0 | 11 | - Neither the name of Internet Society, IETF or IETF Trust, nor the |
| michael@0 | 12 | names of specific contributors, may be used to endorse or promote |
| michael@0 | 13 | products derived from this software without specific prior written |
| michael@0 | 14 | permission. |
| michael@0 | 15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| michael@0 | 16 | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| michael@0 | 17 | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| michael@0 | 18 | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
| michael@0 | 19 | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| michael@0 | 20 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| michael@0 | 21 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| michael@0 | 22 | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| michael@0 | 23 | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| michael@0 | 24 | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| michael@0 | 25 | POSSIBILITY OF SUCH DAMAGE. |
| michael@0 | 26 | ***********************************************************************/ |
| michael@0 | 27 | |
| michael@0 | 28 | #ifdef HAVE_CONFIG_H |
| michael@0 | 29 | #include "config.h" |
| michael@0 | 30 | #endif |
| michael@0 | 31 | |
| michael@0 | 32 | /* Approximate sigmoid function */ |
| michael@0 | 33 | |
| michael@0 | 34 | #include "SigProc_FIX.h" |
| michael@0 | 35 | |
| michael@0 | 36 | /* fprintf(1, '%d, ', round(1024 * ([1 ./ (1 + exp(-(1:5))), 1] - 1 ./ (1 + exp(-(0:5)))))); */ |
| michael@0 | 37 | static const opus_int32 sigm_LUT_slope_Q10[ 6 ] = { |
| michael@0 | 38 | 237, 153, 73, 30, 12, 7 |
| michael@0 | 39 | }; |
| michael@0 | 40 | /* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp(-(0:5))))); */ |
| michael@0 | 41 | static const opus_int32 sigm_LUT_pos_Q15[ 6 ] = { |
| michael@0 | 42 | 16384, 23955, 28861, 31213, 32178, 32548 |
| michael@0 | 43 | }; |
| michael@0 | 44 | /* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp((0:5))))); */ |
| michael@0 | 45 | static const opus_int32 sigm_LUT_neg_Q15[ 6 ] = { |
| michael@0 | 46 | 16384, 8812, 3906, 1554, 589, 219 |
| michael@0 | 47 | }; |
| michael@0 | 48 | |
| michael@0 | 49 | opus_int silk_sigm_Q15( |
| michael@0 | 50 | opus_int in_Q5 /* I */ |
| michael@0 | 51 | ) |
| michael@0 | 52 | { |
| michael@0 | 53 | opus_int ind; |
| michael@0 | 54 | |
| michael@0 | 55 | if( in_Q5 < 0 ) { |
| michael@0 | 56 | /* Negative input */ |
| michael@0 | 57 | in_Q5 = -in_Q5; |
| michael@0 | 58 | if( in_Q5 >= 6 * 32 ) { |
| michael@0 | 59 | return 0; /* Clip */ |
| michael@0 | 60 | } else { |
| michael@0 | 61 | /* Linear interpolation of look up table */ |
| michael@0 | 62 | ind = silk_RSHIFT( in_Q5, 5 ); |
| michael@0 | 63 | return( sigm_LUT_neg_Q15[ ind ] - silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) ); |
| michael@0 | 64 | } |
| michael@0 | 65 | } else { |
| michael@0 | 66 | /* Positive input */ |
| michael@0 | 67 | if( in_Q5 >= 6 * 32 ) { |
| michael@0 | 68 | return 32767; /* clip */ |
| michael@0 | 69 | } else { |
| michael@0 | 70 | /* Linear interpolation of look up table */ |
| michael@0 | 71 | ind = silk_RSHIFT( in_Q5, 5 ); |
| michael@0 | 72 | return( sigm_LUT_pos_Q15[ ind ] + silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) ); |
| michael@0 | 73 | } |
| michael@0 | 74 | } |
| michael@0 | 75 | } |
| michael@0 | 76 |
