Line data    Source code

       1             : /***********************************************************************
       2             : Copyright (c) 2013, Koen Vos. 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             : /* Convert int32 coefficients to int16 coefs and make sure there's no wrap-around */
      35           0 : void silk_LPC_fit(
      36             :     opus_int16                  *a_QOUT,            /* O    Output signal                                               */
      37             :     opus_int32                    *a_QIN,             /* I/O  Input signal                                                */
      38             :     const opus_int              QOUT,               /* I    Input Q domain                                              */
      39             :     const opus_int              QIN,                /* I    Input Q domain                                              */
      40             :     const opus_int              d                   /* I    Filter order                                                */
      41             : )
      42             : {
      43           0 :     opus_int    i, k, idx = 0;
      44             :     opus_int32    maxabs, absval, chirp_Q16;
      45             : 
      46             :     /* Limit the maximum absolute value of the prediction coefficients, so that they'll fit in int16 */
      47           0 :     for( i = 0; i < 10; i++ ) {
      48             :         /* Find maximum absolute value and its index */
      49           0 :         maxabs = 0;
      50           0 :         for( k = 0; k < d; k++ ) {
      51           0 :             absval = silk_abs( a_QIN[k] );
      52           0 :             if( absval > maxabs ) {
      53           0 :                 maxabs = absval;
      54           0 :                 idx    = k;
      55             :             }
      56             :         }
      57           0 :         maxabs = silk_RSHIFT_ROUND( maxabs, QIN - QOUT );
      58             : 
      59           0 :         if( maxabs > silk_int16_MAX ) {
      60             :             /* Reduce magnitude of prediction coefficients */
      61           0 :             maxabs = silk_min( maxabs, 163838 );  /* ( silk_int32_MAX >> 14 ) + silk_int16_MAX = 163838 */
      62           0 :             chirp_Q16 = SILK_FIX_CONST( 0.999, 16 ) - silk_DIV32( silk_LSHIFT( maxabs - silk_int16_MAX, 14 ),
      63             :                                         silk_RSHIFT32( silk_MUL( maxabs, idx + 1), 2 ) );
      64           0 :             silk_bwexpander_32( a_QIN, d, chirp_Q16 );
      65             :         } else {
      66           0 :             break;
      67             :         }
      68             :     }
      69             : 
      70           0 :     if( i == 10 ) {
      71             :         /* Reached the last iteration, clip the coefficients */
      72           0 :         for( k = 0; k < d; k++ ) {
      73           0 :             a_QOUT[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( a_QIN[ k ], QIN - QOUT ) );
      74           0 :             a_QIN[ k ] = silk_LSHIFT( (opus_int32)a_QOUT[ k ], QIN - QOUT );
      75             :         }
      76             :     } else {
      77           0 :         for( k = 0; k < d; k++ ) {
      78           0 :             a_QOUT[ k ] = (opus_int16)silk_RSHIFT_ROUND( a_QIN[ k ], QIN - QOUT );
      79             :         }
      80             :     }
      81           0 : }