1/*********************************************************************** 2Copyright (c) 2006-2011, Skype Limited. All rights reserved. 3Redistribution and use in source and binary forms, with or without 4modification, are permitted provided that the following conditions 5are met: 6- Redistributions of source code must retain the above copyright notice, 7this list of conditions and the following disclaimer. 8- Redistributions in binary form must reproduce the above copyright 9notice, this list of conditions and the following disclaimer in the 10documentation and/or other materials provided with the distribution. 11- Neither the name of Internet Society, IETF or IETF Trust, nor the 12names of specific contributors, may be used to endorse or promote 13products derived from this software without specific prior written 14permission. 15THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 16AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 19LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 20CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 21SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 22INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 23CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 24ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 25POSSIBILITY OF SUCH DAMAGE. 26***********************************************************************/ 27 28#ifdef HAVE_CONFIG_H 29#include "config.h" 30#endif 31 32#include "SigProc_FIX.h" 33#include "celt_lpc.h" 34 35/*******************************************/ 36/* LPC analysis filter */ 37/* NB! State is kept internally and the */ 38/* filter always starts with zero state */ 39/* first d output samples are set to zero */ 40/*******************************************/ 41 42void silk_LPC_analysis_filter( 43 opus_int16 *out, /* O Output signal */ 44 const opus_int16 *in, /* I Input signal */ 45 const opus_int16 *B, /* I MA prediction coefficients, Q12 [order] */ 46 const opus_int32 len, /* I Signal length */ 47 const opus_int32 d /* I Filter order */ 48) 49{ 50 opus_int j; 51#ifdef FIXED_POINT 52 opus_int16 mem[SILK_MAX_ORDER_LPC]; 53 opus_int16 num[SILK_MAX_ORDER_LPC]; 54#else 55 int ix; 56 opus_int32 out32_Q12, out32; 57 const opus_int16 *in_ptr; 58#endif 59 60 silk_assert( d >= 6 ); 61 silk_assert( (d & 1) == 0 ); 62 silk_assert( d <= len ); 63 64#ifdef FIXED_POINT 65 silk_assert( d <= SILK_MAX_ORDER_LPC ); 66 for ( j = 0; j < d; j++ ) { 67 num[ j ] = -B[ j ]; 68 } 69 for (j=0;j<d;j++) { 70 mem[ j ] = in[ d - j - 1 ]; 71 } 72 celt_fir( in + d, num, out + d, len - d, d, mem ); 73 for ( j = 0; j < d; j++ ) { 74 out[ j ] = 0; 75 } 76#else 77 for( ix = d; ix < len; ix++ ) { 78 in_ptr = &in[ ix - 1 ]; 79 80 out32_Q12 = silk_SMULBB( in_ptr[ 0 ], B[ 0 ] ); 81 /* Allowing wrap around so that two wraps can cancel each other. The rare 82 cases where the result wraps around can only be triggered by invalid streams*/ 83 out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -1 ], B[ 1 ] ); 84 out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -2 ], B[ 2 ] ); 85 out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -3 ], B[ 3 ] ); 86 out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -4 ], B[ 4 ] ); 87 out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -5 ], B[ 5 ] ); 88 for( j = 6; j < d; j += 2 ) { 89 out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -j ], B[ j ] ); 90 out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -j - 1 ], B[ j + 1 ] ); 91 } 92 93 /* Subtract prediction */ 94 out32_Q12 = silk_SUB32_ovflw( silk_LSHIFT( (opus_int32)in_ptr[ 1 ], 12 ), out32_Q12 ); 95 96 /* Scale to Q0 */ 97 out32 = silk_RSHIFT_ROUND( out32_Q12, 12 ); 98 99 /* Saturate output */ 100 out[ ix ] = (opus_int16)silk_SAT16( out32 ); 101 } 102 103 /* Set first d output samples to zero */ 104 silk_memset( out, 0, d * sizeof( opus_int16 ) ); 105#endif 106} 107