78 lines
4.3 KiB
C
78 lines
4.3 KiB
C
/***********************************************************************
|
|
Copyright (c) 2006-2011, Skype Limited. All rights reserved.
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, are permitted provided that the following conditions
|
|
are met:
|
|
- Redistributions of source code must retain the above copyright notice,
|
|
this list of conditions and the following disclaimer.
|
|
- Redistributions in binary form must reproduce the above copyright
|
|
notice, this list of conditions and the following disclaimer in the
|
|
documentation and/or other materials provided with the distribution.
|
|
- Neither the name of Internet Society, IETF or IETF Trust, nor the
|
|
names of specific contributors, may be used to endorse or promote
|
|
products derived from this software without specific prior written
|
|
permission.
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
POSSIBILITY OF SUCH DAMAGE.
|
|
***********************************************************************/
|
|
|
|
/* *
|
|
* silk_biquad_alt.c *
|
|
* *
|
|
* Second order ARMA filter *
|
|
* Can handle slowly varying filter coefficients *
|
|
* */
|
|
|
|
#ifdef OPUS_ENABLED
|
|
#include "opus/opus_config.h"
|
|
#endif
|
|
|
|
#include "opus/silk/SigProc_FIX.h"
|
|
|
|
/* Second order ARMA filter, alternative implementation */
|
|
void silk_biquad_alt(
|
|
const opus_int16 *in, /* I input signal */
|
|
const opus_int32 *B_Q28, /* I MA coefficients [3] */
|
|
const opus_int32 *A_Q28, /* I AR coefficients [2] */
|
|
opus_int32 *S, /* I/O State vector [2] */
|
|
opus_int16 *out, /* O output signal */
|
|
const opus_int32 len, /* I signal length (must be even) */
|
|
opus_int stride /* I Operate on interleaved signal if > 1 */
|
|
)
|
|
{
|
|
/* DIRECT FORM II TRANSPOSED (uses 2 element state vector) */
|
|
opus_int k;
|
|
opus_int32 inval, A0_U_Q28, A0_L_Q28, A1_U_Q28, A1_L_Q28, out32_Q14;
|
|
|
|
/* Negate A_Q28 values and split in two parts */
|
|
A0_L_Q28 = ( -A_Q28[ 0 ] ) & 0x00003FFF; /* lower part */
|
|
A0_U_Q28 = silk_RSHIFT( -A_Q28[ 0 ], 14 ); /* upper part */
|
|
A1_L_Q28 = ( -A_Q28[ 1 ] ) & 0x00003FFF; /* lower part */
|
|
A1_U_Q28 = silk_RSHIFT( -A_Q28[ 1 ], 14 ); /* upper part */
|
|
|
|
for( k = 0; k < len; k++ ) {
|
|
/* S[ 0 ], S[ 1 ]: Q12 */
|
|
inval = in[ k * stride ];
|
|
out32_Q14 = silk_LSHIFT( silk_SMLAWB( S[ 0 ], B_Q28[ 0 ], inval ), 2 );
|
|
|
|
S[ 0 ] = S[1] + silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14, A0_L_Q28 ), 14 );
|
|
S[ 0 ] = silk_SMLAWB( S[ 0 ], out32_Q14, A0_U_Q28 );
|
|
S[ 0 ] = silk_SMLAWB( S[ 0 ], B_Q28[ 1 ], inval);
|
|
|
|
S[ 1 ] = silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14, A1_L_Q28 ), 14 );
|
|
S[ 1 ] = silk_SMLAWB( S[ 1 ], out32_Q14, A1_U_Q28 );
|
|
S[ 1 ] = silk_SMLAWB( S[ 1 ], B_Q28[ 2 ], inval );
|
|
|
|
/* Scale back to Q0 and saturate */
|
|
out[ k * stride ] = (opus_int16)silk_SAT16( silk_RSHIFT( out32_Q14 + (1<<14) - 1, 14 ) );
|
|
}
|
|
}
|