Gregory Maxwell | ae23114 | 2011-07-30 08:18:48 -0400 | [diff] [blame] | 1 | /*********************************************************************** |
| 2 | Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
| 3 | Redistribution and use in source and binary forms, with or without |
Jean-Marc Valin | ae00e60 | 2012-04-20 16:31:04 -0400 | [diff] [blame] | 4 | modification, are permitted provided that the following conditions |
| 5 | are met: |
Gregory Maxwell | ae23114 | 2011-07-30 08:18:48 -0400 | [diff] [blame] | 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. |
Jean-Marc Valin | ae00e60 | 2012-04-20 16:31:04 -0400 | [diff] [blame] | 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 |
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| 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 |
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| 25 | POSSIBILITY OF SUCH DAMAGE. |
Gregory Maxwell | ae23114 | 2011-07-30 08:18:48 -0400 | [diff] [blame] | 26 | ***********************************************************************/ |
| 27 | |
Jean-Marc Valin | 5a48412 | 2011-08-15 10:49:53 -0400 | [diff] [blame] | 28 | #ifdef HAVE_CONFIG_H |
| 29 | #include "config.h" |
| 30 | #endif |
| 31 | |
Jean-Marc Valin | 1c2f563 | 2011-09-16 01:16:53 -0700 | [diff] [blame] | 32 | #include "SigProc_FIX.h" |
Gregory Maxwell | ae23114 | 2011-07-30 08:18:48 -0400 | [diff] [blame] | 33 | /* Approximation of 128 * log2() (very close inverse of silk_log2lin()) */ |
| 34 | /* Convert input to a log scale */ |
Ralph Giles | 5f6e472 | 2012-03-19 17:10:13 -0700 | [diff] [blame] | 35 | opus_int32 silk_lin2log( |
Koen Vos | acc7a6c | 2011-10-28 19:44:26 -0400 | [diff] [blame] | 36 | const opus_int32 inLin /* I input in linear scale */ |
| 37 | ) |
Gregory Maxwell | ae23114 | 2011-07-30 08:18:48 -0400 | [diff] [blame] | 38 | { |
| 39 | opus_int32 lz, frac_Q7; |
| 40 | |
| 41 | silk_CLZ_FRAC( inLin, &lz, &frac_Q7 ); |
| 42 | |
| 43 | /* Piece-wise parabolic approximation */ |
Jean-Marc Valin | fb3a437 | 2011-09-16 00:58:26 -0700 | [diff] [blame] | 44 | return silk_LSHIFT( 31 - lz, 7 ) + silk_SMLAWB( frac_Q7, silk_MUL( frac_Q7, 128 - frac_Q7 ), 179 ); |
Gregory Maxwell | ae23114 | 2011-07-30 08:18:48 -0400 | [diff] [blame] | 45 | } |
| 46 | |