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. |
| 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 | |
| 34 | /* Faster than schur64(), but much less accurate. */ |
| 35 | /* uses SMLAWB(), requiring armv5E and higher. */ |
| 36 | opus_int32 silk_schur( /* O Returns residual energy */ |
| 37 | opus_int16 *rc_Q15, /* O reflection coefficients [order] Q15 */ |
| 38 | const opus_int32 *c, /* I correlations [order+1] */ |
| 39 | const opus_int32 order /* I prediction order */ |
| 40 | ) |
| 41 | { |
| 42 | opus_int k, n, lz; |
| 43 | opus_int32 C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ]; |
| 44 | opus_int32 Ctmp1, Ctmp2, rc_tmp_Q15; |
| 45 | |
| 46 | silk_assert( order==6||order==8||order==10||order==12||order==14||order==16 ); |
| 47 | |
| 48 | /* Get number of leading zeros */ |
| 49 | lz = silk_CLZ32( c[ 0 ] ); |
| 50 | |
| 51 | /* Copy correlations and adjust level to Q30 */ |
| 52 | if( lz < 2 ) { |
| 53 | /* lz must be 1, so shift one to the right */ |
| 54 | for( k = 0; k < order + 1; k++ ) { |
| 55 | C[ k ][ 0 ] = C[ k ][ 1 ] = silk_RSHIFT( c[ k ], 1 ); |
| 56 | } |
| 57 | } else if( lz > 2 ) { |
| 58 | /* Shift to the left */ |
| 59 | lz -= 2; |
| 60 | for( k = 0; k < order + 1; k++ ) { |
| 61 | C[ k ][ 0 ] = C[ k ][ 1 ] = silk_LSHIFT( c[ k ], lz ); |
| 62 | } |
| 63 | } else { |
| 64 | /* No need to shift */ |
| 65 | for( k = 0; k < order + 1; k++ ) { |
| 66 | C[ k ][ 0 ] = C[ k ][ 1 ] = c[ k ]; |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | for( k = 0; k < order; k++ ) { |
| 71 | /* Check that we won't be getting an unstable rc, otherwise stop here. */ |
| 72 | if (silk_abs_int32(C[ k + 1 ][ 0 ]) >= C[ 0 ][ 1 ]) { |
| 73 | if ( C[ k + 1 ][ 0 ] > 0 ) { |
| 74 | rc_Q15[ k ] = -SILK_FIX_CONST( .99f, 15 ); |
| 75 | } else { |
| 76 | rc_Q15[ k ] = SILK_FIX_CONST( .99f, 15 ); |
| 77 | } |
| 78 | k++; |
| 79 | break; |
| 80 | } |
| 81 | |
| 82 | /* Get reflection coefficient */ |
| 83 | rc_tmp_Q15 = -silk_DIV32_16( C[ k + 1 ][ 0 ], silk_max_32( silk_RSHIFT( C[ 0 ][ 1 ], 15 ), 1 ) ); |
| 84 | |
| 85 | /* Clip (shouldn't happen for properly conditioned inputs) */ |
| 86 | rc_tmp_Q15 = silk_SAT16( rc_tmp_Q15 ); |
| 87 | |
| 88 | /* Store */ |
| 89 | rc_Q15[ k ] = (opus_int16)rc_tmp_Q15; |
| 90 | |
| 91 | /* Update correlations */ |
| 92 | for( n = 0; n < order - k; n++ ) { |
| 93 | Ctmp1 = C[ n + k + 1 ][ 0 ]; |
| 94 | Ctmp2 = C[ n ][ 1 ]; |
| 95 | C[ n + k + 1 ][ 0 ] = silk_SMLAWB( Ctmp1, silk_LSHIFT( Ctmp2, 1 ), rc_tmp_Q15 ); |
| 96 | C[ n ][ 1 ] = silk_SMLAWB( Ctmp2, silk_LSHIFT( Ctmp1, 1 ), rc_tmp_Q15 ); |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | for(; k < order; k++ ) { |
| 101 | rc_Q15[ k ] = 0; |
| 102 | } |
| 103 | |
| 104 | /* return residual energy */ |
| 105 | return silk_max_32( 1, C[ 0 ][ 1 ] ); |
| 106 | } |