diff options
Diffstat (limited to 'lib/rbcodec/codecs/libopus/silk/sigm_Q15.c')
-rw-r--r-- | lib/rbcodec/codecs/libopus/silk/sigm_Q15.c | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/lib/rbcodec/codecs/libopus/silk/sigm_Q15.c b/lib/rbcodec/codecs/libopus/silk/sigm_Q15.c new file mode 100644 index 0000000000..3c507d255b --- /dev/null +++ b/lib/rbcodec/codecs/libopus/silk/sigm_Q15.c | |||
@@ -0,0 +1,76 @@ | |||
1 | /*********************************************************************** | ||
2 | Copyright (c) 2006-2011, Skype Limited. All rights reserved. | ||
3 | Redistribution and use in source and binary forms, with or without | ||
4 | modification, are permitted provided that the following conditions | ||
5 | are met: | ||
6 | - Redistributions of source code must retain the above copyright notice, | ||
7 | this list of conditions and the following disclaimer. | ||
8 | - Redistributions in binary form must reproduce the above copyright | ||
9 | notice, this list of conditions and the following disclaimer in the | ||
10 | documentation and/or other materials provided with the distribution. | ||
11 | - Neither the name of Internet Society, IETF or IETF Trust, nor the | ||
12 | names of specific contributors, may be used to endorse or promote | ||
13 | products derived from this software without specific prior written | ||
14 | permission. | ||
15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | ||
16 | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | ||
17 | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | ||
18 | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE | ||
19 | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | ||
20 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | ||
21 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | ||
22 | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | ||
23 | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | ||
24 | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | ||
25 | POSSIBILITY OF SUCH DAMAGE. | ||
26 | ***********************************************************************/ | ||
27 | |||
28 | #ifdef HAVE_CONFIG_H | ||
29 | #include "config.h" | ||
30 | #endif | ||
31 | |||
32 | /* Approximate sigmoid function */ | ||
33 | |||
34 | #include "SigProc_FIX.h" | ||
35 | |||
36 | /* fprintf(1, '%d, ', round(1024 * ([1 ./ (1 + exp(-(1:5))), 1] - 1 ./ (1 + exp(-(0:5)))))); */ | ||
37 | static const opus_int32 sigm_LUT_slope_Q10[ 6 ] = { | ||
38 | 237, 153, 73, 30, 12, 7 | ||
39 | }; | ||
40 | /* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp(-(0:5))))); */ | ||
41 | static const opus_int32 sigm_LUT_pos_Q15[ 6 ] = { | ||
42 | 16384, 23955, 28861, 31213, 32178, 32548 | ||
43 | }; | ||
44 | /* fprintf(1, '%d, ', round(32767 * 1 ./ (1 + exp((0:5))))); */ | ||
45 | static const opus_int32 sigm_LUT_neg_Q15[ 6 ] = { | ||
46 | 16384, 8812, 3906, 1554, 589, 219 | ||
47 | }; | ||
48 | |||
49 | opus_int silk_sigm_Q15( | ||
50 | opus_int in_Q5 /* I */ | ||
51 | ) | ||
52 | { | ||
53 | opus_int ind; | ||
54 | |||
55 | if( in_Q5 < 0 ) { | ||
56 | /* Negative input */ | ||
57 | in_Q5 = -in_Q5; | ||
58 | if( in_Q5 >= 6 * 32 ) { | ||
59 | return 0; /* Clip */ | ||
60 | } else { | ||
61 | /* Linear interpolation of look up table */ | ||
62 | ind = silk_RSHIFT( in_Q5, 5 ); | ||
63 | return( sigm_LUT_neg_Q15[ ind ] - silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) ); | ||
64 | } | ||
65 | } else { | ||
66 | /* Positive input */ | ||
67 | if( in_Q5 >= 6 * 32 ) { | ||
68 | return 32767; /* clip */ | ||
69 | } else { | ||
70 | /* Linear interpolation of look up table */ | ||
71 | ind = silk_RSHIFT( in_Q5, 5 ); | ||
72 | return( sigm_LUT_pos_Q15[ ind ] + silk_SMULBB( sigm_LUT_slope_Q10[ ind ], in_Q5 & 0x1F ) ); | ||
73 | } | ||
74 | } | ||
75 | } | ||
76 | |||