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| 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-aroun
d */ |
| 35 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 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 for( i = 0; i < 10; i++ ) { |
| 48 /* Find maximum absolute value and its index */ |
| 49 maxabs = 0; |
| 50 for( k = 0; k < d; k++ ) { |
| 51 absval = silk_abs( a_QIN[k] ); |
| 52 if( absval > maxabs ) { |
| 53 maxabs = absval; |
| 54 idx = k; |
| 55 } |
| 56 } |
| 57 maxabs = silk_RSHIFT_ROUND( maxabs, QIN - QOUT ); |
| 58 |
| 59 if( maxabs > silk_int16_MAX ) { |
| 60 /* Reduce magnitude of prediction coefficients */ |
| 61 maxabs = silk_min( maxabs, 163838 ); /* ( silk_int32_MAX >> 14 ) +
silk_int16_MAX = 163838 */ |
| 62 chirp_Q16 = SILK_FIX_CONST( 0.999, 16 ) - silk_DIV32( silk_LSHIFT( m
axabs - silk_int16_MAX, 14 ), |
| 63 silk_RSHIFT32( silk_MUL( maxabs, idx + 1
), 2 ) ); |
| 64 silk_bwexpander_32( a_QIN, d, chirp_Q16 ); |
| 65 } else { |
| 66 break; |
| 67 } |
| 68 } |
| 69 |
| 70 if( i == 10 ) { |
| 71 /* Reached the last iteration, clip the coefficients */ |
| 72 for( k = 0; k < d; k++ ) { |
| 73 a_QOUT[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( a_QIN[ k ],
QIN - QOUT ) ); |
| 74 a_QIN[ k ] = silk_LSHIFT( (opus_int32)a_QOUT[ k ], QIN - QOUT ); |
| 75 } |
| 76 } else { |
| 77 for( k = 0; k < d; k++ ) { |
| 78 a_QOUT[ k ] = (opus_int16)silk_RSHIFT_ROUND( a_QIN[ k ], QIN - QOUT
); |
| 79 } |
| 80 } |
| 81 } |
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