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comparison: media/libopus/silk/biquad_alt.c
media/libopus/silk/biquad_alt.c
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:4368617f00f4 |
|---|---|
| 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 /* * | |
| 29 * silk_biquad_alt.c * | |
| 30 * * | |
| 31 * Second order ARMA filter * | |
| 32 * Can handle slowly varying filter coefficients * | |
| 33 * */ | |
| 34 | |
| 35 #ifdef HAVE_CONFIG_H | |
| 36 #include "config.h" | |
| 37 #endif | |
| 38 | |
| 39 #include "SigProc_FIX.h" | |
| 40 | |
| 41 /* Second order ARMA filter, alternative implementation */ | |
| 42 void silk_biquad_alt( | |
| 43 const opus_int16 *in, /* I input signal */ | |
| 44 const opus_int32 *B_Q28, /* I MA coefficients [3] */ | |
| 45 const opus_int32 *A_Q28, /* I AR coefficients [2] */ | |
| 46 opus_int32 *S, /* I/O State vector [2] */ | |
| 47 opus_int16 *out, /* O output signal */ | |
| 48 const opus_int32 len, /* I signal length (must be even) */ | |
| 49 opus_int stride /* I Operate on interleaved signal if > 1 */ | |
| 50 ) | |
| 51 { | |
| 52 /* DIRECT FORM II TRANSPOSED (uses 2 element state vector) */ | |
| 53 opus_int k; | |
| 54 opus_int32 inval, A0_U_Q28, A0_L_Q28, A1_U_Q28, A1_L_Q28, out32_Q14; | |
| 55 | |
| 56 /* Negate A_Q28 values and split in two parts */ | |
| 57 A0_L_Q28 = ( -A_Q28[ 0 ] ) & 0x00003FFF; /* lower part */ | |
| 58 A0_U_Q28 = silk_RSHIFT( -A_Q28[ 0 ], 14 ); /* upper part */ | |
| 59 A1_L_Q28 = ( -A_Q28[ 1 ] ) & 0x00003FFF; /* lower part */ | |
| 60 A1_U_Q28 = silk_RSHIFT( -A_Q28[ 1 ], 14 ); /* upper part */ | |
| 61 | |
| 62 for( k = 0; k < len; k++ ) { | |
| 63 /* S[ 0 ], S[ 1 ]: Q12 */ | |
| 64 inval = in[ k * stride ]; | |
| 65 out32_Q14 = silk_LSHIFT( silk_SMLAWB( S[ 0 ], B_Q28[ 0 ], inval ), 2 ); | |
| 66 | |
| 67 S[ 0 ] = S[1] + silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14, A0_L_Q28 ), 14 ); | |
| 68 S[ 0 ] = silk_SMLAWB( S[ 0 ], out32_Q14, A0_U_Q28 ); | |
| 69 S[ 0 ] = silk_SMLAWB( S[ 0 ], B_Q28[ 1 ], inval); | |
| 70 | |
| 71 S[ 1 ] = silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14, A1_L_Q28 ), 14 ); | |
| 72 S[ 1 ] = silk_SMLAWB( S[ 1 ], out32_Q14, A1_U_Q28 ); | |
| 73 S[ 1 ] = silk_SMLAWB( S[ 1 ], B_Q28[ 2 ], inval ); | |
| 74 | |
| 75 /* Scale back to Q0 and saturate */ | |
| 76 out[ k * stride ] = (opus_int16)silk_SAT16( silk_RSHIFT( out32_Q14 + (1<<14) - 1, 14 ) ); | |
| 77 } | |
| 78 } |
