diff options
Diffstat (limited to 'lib/rbcodec/codecs/libopus/silk/log2lin.c')
-rw-r--r-- | lib/rbcodec/codecs/libopus/silk/log2lin.c | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/lib/rbcodec/codecs/libopus/silk/log2lin.c b/lib/rbcodec/codecs/libopus/silk/log2lin.c new file mode 100644 index 0000000000..d80472c69f --- /dev/null +++ b/lib/rbcodec/codecs/libopus/silk/log2lin.c | |||
@@ -0,0 +1,56 @@ | |||
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 "opus_config.h" | ||
30 | #endif | ||
31 | |||
32 | #include "SigProc_FIX.h" | ||
33 | |||
34 | /* Approximation of 2^() (very close inverse of silk_lin2log()) */ | ||
35 | /* Convert input to a linear scale */ | ||
36 | opus_int32 silk_log2lin( | ||
37 | const opus_int32 inLog_Q7 /* I input on log scale */ | ||
38 | ) | ||
39 | { | ||
40 | opus_int32 out, frac_Q7; | ||
41 | |||
42 | if( inLog_Q7 < 0 ) { | ||
43 | return 0; | ||
44 | } | ||
45 | |||
46 | out = silk_LSHIFT( 1, silk_RSHIFT( inLog_Q7, 7 ) ); | ||
47 | frac_Q7 = inLog_Q7 & 0x7F; | ||
48 | if( inLog_Q7 < 2048 ) { | ||
49 | /* Piece-wise parabolic approximation */ | ||
50 | out = silk_ADD_RSHIFT32( out, silk_MUL( out, silk_SMLAWB( frac_Q7, silk_SMULBB( frac_Q7, 128 - frac_Q7 ), -174 ) ), 7 ); | ||
51 | } else { | ||
52 | /* Piece-wise parabolic approximation */ | ||
53 | out = silk_MLA( out, silk_RSHIFT( out, 7 ), silk_SMLAWB( frac_Q7, silk_SMULBB( frac_Q7, 128 - frac_Q7 ), -174 ) ); | ||
54 | } | ||
55 | return out; | ||
56 | } | ||