1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/biquad_alt.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,78 @@
1.4 +/***********************************************************************
1.5 +Copyright (c) 2006-2011, Skype Limited. All rights reserved.
1.6 +Redistribution and use in source and binary forms, with or without
1.7 +modification, are permitted provided that the following conditions
1.8 +are met:
1.9 +- Redistributions of source code must retain the above copyright notice,
1.10 +this list of conditions and the following disclaimer.
1.11 +- Redistributions in binary form must reproduce the above copyright
1.12 +notice, this list of conditions and the following disclaimer in the
1.13 +documentation and/or other materials provided with the distribution.
1.14 +- Neither the name of Internet Society, IETF or IETF Trust, nor the
1.15 +names of specific contributors, may be used to endorse or promote
1.16 +products derived from this software without specific prior written
1.17 +permission.
1.18 +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.19 +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.20 +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.21 +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
1.22 +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.23 +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.24 +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.25 +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.26 +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.27 +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.28 +POSSIBILITY OF SUCH DAMAGE.
1.29 +***********************************************************************/
1.30 +
1.31 +/* *
1.32 + * silk_biquad_alt.c *
1.33 + * *
1.34 + * Second order ARMA filter *
1.35 + * Can handle slowly varying filter coefficients *
1.36 + * */
1.37 +
1.38 +#ifdef HAVE_CONFIG_H
1.39 +#include "config.h"
1.40 +#endif
1.41 +
1.42 +#include "SigProc_FIX.h"
1.43 +
1.44 +/* Second order ARMA filter, alternative implementation */
1.45 +void silk_biquad_alt(
1.46 + const opus_int16 *in, /* I input signal */
1.47 + const opus_int32 *B_Q28, /* I MA coefficients [3] */
1.48 + const opus_int32 *A_Q28, /* I AR coefficients [2] */
1.49 + opus_int32 *S, /* I/O State vector [2] */
1.50 + opus_int16 *out, /* O output signal */
1.51 + const opus_int32 len, /* I signal length (must be even) */
1.52 + opus_int stride /* I Operate on interleaved signal if > 1 */
1.53 +)
1.54 +{
1.55 + /* DIRECT FORM II TRANSPOSED (uses 2 element state vector) */
1.56 + opus_int k;
1.57 + opus_int32 inval, A0_U_Q28, A0_L_Q28, A1_U_Q28, A1_L_Q28, out32_Q14;
1.58 +
1.59 + /* Negate A_Q28 values and split in two parts */
1.60 + A0_L_Q28 = ( -A_Q28[ 0 ] ) & 0x00003FFF; /* lower part */
1.61 + A0_U_Q28 = silk_RSHIFT( -A_Q28[ 0 ], 14 ); /* upper part */
1.62 + A1_L_Q28 = ( -A_Q28[ 1 ] ) & 0x00003FFF; /* lower part */
1.63 + A1_U_Q28 = silk_RSHIFT( -A_Q28[ 1 ], 14 ); /* upper part */
1.64 +
1.65 + for( k = 0; k < len; k++ ) {
1.66 + /* S[ 0 ], S[ 1 ]: Q12 */
1.67 + inval = in[ k * stride ];
1.68 + out32_Q14 = silk_LSHIFT( silk_SMLAWB( S[ 0 ], B_Q28[ 0 ], inval ), 2 );
1.69 +
1.70 + S[ 0 ] = S[1] + silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14, A0_L_Q28 ), 14 );
1.71 + S[ 0 ] = silk_SMLAWB( S[ 0 ], out32_Q14, A0_U_Q28 );
1.72 + S[ 0 ] = silk_SMLAWB( S[ 0 ], B_Q28[ 1 ], inval);
1.73 +
1.74 + S[ 1 ] = silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14, A1_L_Q28 ), 14 );
1.75 + S[ 1 ] = silk_SMLAWB( S[ 1 ], out32_Q14, A1_U_Q28 );
1.76 + S[ 1 ] = silk_SMLAWB( S[ 1 ], B_Q28[ 2 ], inval );
1.77 +
1.78 + /* Scale back to Q0 and saturate */
1.79 + out[ k * stride ] = (opus_int16)silk_SAT16( silk_RSHIFT( out32_Q14 + (1<<14) - 1, 14 ) );
1.80 + }
1.81 +}
