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Diffstat (limited to 'lib/rbcodec/codecs/libopus/silk/lin2log.c')
-rw-r--r-- | lib/rbcodec/codecs/libopus/silk/lin2log.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/lib/rbcodec/codecs/libopus/silk/lin2log.c b/lib/rbcodec/codecs/libopus/silk/lin2log.c new file mode 100644 index 0000000000..0d5155aa86 --- /dev/null +++ b/lib/rbcodec/codecs/libopus/silk/lin2log.c | |||
@@ -0,0 +1,46 @@ | |||
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 | #include "SigProc_FIX.h" | ||
33 | /* Approximation of 128 * log2() (very close inverse of silk_log2lin()) */ | ||
34 | /* Convert input to a log scale */ | ||
35 | opus_int32 silk_lin2log( | ||
36 | const opus_int32 inLin /* I input in linear scale */ | ||
37 | ) | ||
38 | { | ||
39 | opus_int32 lz, frac_Q7; | ||
40 | |||
41 | silk_CLZ_FRAC( inLin, &lz, &frac_Q7 ); | ||
42 | |||
43 | /* Piece-wise parabolic approximation */ | ||
44 | return silk_ADD_LSHIFT32( silk_SMLAWB( frac_Q7, silk_MUL( frac_Q7, 128 - frac_Q7 ), 179 ), 31 - lz, 7 ); | ||
45 | } | ||
46 | |||