gecko/media/libopus/silk/biquad_alt.c
Ralph Giles 3ae1b38243 Bug 916807 - Update opus to 1.1 prerelease. r=derf
Update our opus implementation to a prerelease of 1.1. This
brings many performance and encoder improvements and we believe
it is stable enough to switch. This import does not enable any
of the new assembly optimizations.

The imported code is https://git.xiph.org/opus.git master
commit f2446c25c6519bae190152f7a579310b83dc43fd.
2013-09-16 14:48:00 -07:00

79 lines
4.2 KiB
C

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/* *
* silk_biquad_alt.c *
* *
* Second order ARMA filter *
* Can handle slowly varying filter coefficients *
* */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "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 ) );
}
}