Line data    Source code

       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             : #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             : 
      42             : /* OPT: Using celt_fir() for this function should be faster, but it may cause
      43             :    integer overflows in intermediate values (not final results), which the
      44             :    current implementation silences by casting to unsigned. Enabling
      45             :    this should be safe in pretty much all cases, even though it is not technically
      46             :    C89-compliant. */
      47             : #define USE_CELT_FIR 0
      48             : 
      49           0 : void silk_LPC_analysis_filter(
      50             :     opus_int16                  *out,               /* O    Output signal                                               */
      51             :     const opus_int16            *in,                /* I    Input signal                                                */
      52             :     const opus_int16            *B,                 /* I    MA prediction coefficients, Q12 [order]                     */
      53             :     const opus_int32            len,                /* I    Signal length                                               */
      54             :     const opus_int32            d,                  /* I    Filter order                                                */
      55             :     int                         arch                /* I    Run-time architecture                                       */
      56             : )
      57             : {
      58             :     opus_int   j;
      59             : #if defined(FIXED_POINT) && USE_CELT_FIR
      60             :     opus_int16 num[SILK_MAX_ORDER_LPC];
      61             : #else
      62             :     int ix;
      63             :     opus_int32       out32_Q12, out32;
      64             :     const opus_int16 *in_ptr;
      65             : #endif
      66             : 
      67           0 :     silk_assert( d >= 6 );
      68           0 :     silk_assert( (d & 1) == 0 );
      69           0 :     silk_assert( d <= len );
      70             : 
      71             : #if defined(FIXED_POINT) && USE_CELT_FIR
      72             :     silk_assert( d <= SILK_MAX_ORDER_LPC );
      73             :     for ( j = 0; j < d; j++ ) {
      74             :         num[ j ] = -B[ j ];
      75             :     }
      76             :     celt_fir( in + d, num, out + d, len - d, d, arch );
      77             :     for ( j = 0; j < d; j++ ) {
      78             :         out[ j ] = 0;
      79             :     }
      80             : #else
      81             :     (void)arch;
      82           0 :     for( ix = d; ix < len; ix++ ) {
      83           0 :         in_ptr = &in[ ix - 1 ];
      84             : 
      85           0 :         out32_Q12 = silk_SMULBB( in_ptr[  0 ], B[ 0 ] );
      86             :         /* Allowing wrap around so that two wraps can cancel each other. The rare
      87             :            cases where the result wraps around can only be triggered by invalid streams*/
      88           0 :         out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -1 ], B[ 1 ] );
      89           0 :         out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -2 ], B[ 2 ] );
      90           0 :         out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -3 ], B[ 3 ] );
      91           0 :         out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -4 ], B[ 4 ] );
      92           0 :         out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -5 ], B[ 5 ] );
      93           0 :         for( j = 6; j < d; j += 2 ) {
      94           0 :             out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -j     ], B[ j     ] );
      95           0 :             out32_Q12 = silk_SMLABB_ovflw( out32_Q12, in_ptr[ -j - 1 ], B[ j + 1 ] );
      96             :         }
      97             : 
      98             :         /* Subtract prediction */
      99           0 :         out32_Q12 = silk_SUB32_ovflw( silk_LSHIFT( (opus_int32)in_ptr[ 1 ], 12 ), out32_Q12 );
     100             : 
     101             :         /* Scale to Q0 */
     102           0 :         out32 = silk_RSHIFT_ROUND( out32_Q12, 12 );
     103             : 
     104             :         /* Saturate output */
     105           0 :         out[ ix ] = (opus_int16)silk_SAT16( out32 );
     106             :     }
     107             : 
     108             :     /* Set first d output samples to zero */
     109           0 :     silk_memset( out, 0, d * sizeof( opus_int16 ) );
     110             : #endif
     111           0 : }