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author | Jean-Marc Valin <jmvalin@jmvalin.ca> | 2011-09-16 01:16:53 -0700 |
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committer | Jean-Marc Valin <jmvalin@jmvalin.ca> | 2011-09-16 01:16:53 -0700 |
commit | 1c2f5633d101c08b5ef8095a8682d3d52cbd952d (patch) | |
tree | 66f80e67f075db5fa5233759a89f475d8bedade2 /silk/log2lin.c | |
parent | fb3a437c9dabb4aafe4a3927158161590ed745ab (diff) | |
download | opus-1c2f5633d101c08b5ef8095a8682d3d52cbd952d.tar.gz |
Removed all the silk_ prefixes in source file names (not symbols)
Diffstat (limited to 'silk/log2lin.c')
-rw-r--r-- | silk/log2lin.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/silk/log2lin.c b/silk/log2lin.c new file mode 100644 index 00000000..b49dd0a2 --- /dev/null +++ b/silk/log2lin.c @@ -0,0 +1,54 @@ +/*********************************************************************** +Copyright (c) 2006-2011, Skype Limited. All rights reserved. +Redistribution and use in source and binary forms, with or without +modification, (subject to the limitations in the disclaimer below) +are permitted provided that the following conditions are met: +- Redistributions of source code must retain the above copyright notice, +this list of conditions and the following disclaimer. +- Redistributions in binary form must reproduce the above copyright +notice, this list of conditions and the following disclaimer in the +documentation and/or other materials provided with the distribution. +- Neither the name of Skype Limited, nor the names of specific +contributors, may be used to endorse or promote products derived from +this software without specific prior written permission. +NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED +BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND +CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, +BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND +FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE +COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, +INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF +USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON +ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +***********************************************************************/ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "SigProc_FIX.h" + +/* Approximation of 2^() (very close inverse of silk_lin2log()) */ +/* Convert input to a linear scale */ +opus_int32 silk_log2lin( const opus_int32 inLog_Q7 ) /* I: Input on log scale */ +{ + opus_int32 out, frac_Q7; + + if( inLog_Q7 < 0 ) { + return 0; + } + + out = silk_LSHIFT( 1, silk_RSHIFT( inLog_Q7, 7 ) ); + frac_Q7 = inLog_Q7 & 0x7F; + if( inLog_Q7 < 2048 ) { + /* Piece-wise parabolic approximation */ + out = silk_ADD_RSHIFT( out, silk_MUL( out, silk_SMLAWB( frac_Q7, silk_MUL( frac_Q7, 128 - frac_Q7 ), -174 ) ), 7 ); + } else { + /* Piece-wise parabolic approximation */ + out = silk_MLA( out, silk_RSHIFT( out, 7 ), silk_SMLAWB( frac_Q7, silk_MUL( frac_Q7, 128 - frac_Q7 ), -174 ) ); + } + return out; +} |