Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -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 |
| 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. |
Alexandre Lision | 8538238 | 2014-01-27 15:54:16 -0500 | [diff] [blame] | 11 | - Neither the name of Internet Society, IETF or IETF Trust, nor the |
Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -0400 | [diff] [blame] | 12 | names of specific contributors, may be used to endorse or promote |
| 13 | products derived from this software without specific prior written |
| 14 | permission. |
Alexandre Lision | 8538238 | 2014-01-27 15:54:16 -0500 | [diff] [blame] | 15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -0400 | [diff] [blame] | 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 | |
| 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; |
Alexandre Lision | 8538238 | 2014-01-27 15:54:16 -0500 | [diff] [blame] | 44 | } else if ( inLog_Q7 >= 3967 ) { |
| 45 | return silk_int32_MAX; |
| 46 | } |
Alexandre Lision | 744f742 | 2013-09-25 11:39:37 -0400 | [diff] [blame] | 47 | |
| 48 | out = silk_LSHIFT( 1, silk_RSHIFT( inLog_Q7, 7 ) ); |
| 49 | frac_Q7 = inLog_Q7 & 0x7F; |
| 50 | if( inLog_Q7 < 2048 ) { |
| 51 | /* Piece-wise parabolic approximation */ |
| 52 | out = silk_ADD_RSHIFT32( out, silk_MUL( out, silk_SMLAWB( frac_Q7, silk_SMULBB( frac_Q7, 128 - frac_Q7 ), -174 ) ), 7 ); |
| 53 | } else { |
| 54 | /* Piece-wise parabolic approximation */ |
| 55 | out = silk_MLA( out, silk_RSHIFT( out, 7 ), silk_SMLAWB( frac_Q7, silk_SMULBB( frac_Q7, 128 - frac_Q7 ), -174 ) ); |
| 56 | } |
| 57 | return out; |
| 58 | } |