diff options
Diffstat (limited to 'silk/SKP_Silk_LPC_synthesis_filter.c')
| m--------- | silk | 6 | ||||
| -rw-r--r-- | silk/SKP_Silk_LPC_synthesis_filter.c | 84 |
2 files changed, 84 insertions, 6 deletions
diff --git a/silk b/silk deleted file mode 160000 -Subproject 8a8b76efeeccaccf402b0b2b4e469980d0a4831 diff --git a/silk/SKP_Silk_LPC_synthesis_filter.c b/silk/SKP_Silk_LPC_synthesis_filter.c new file mode 100644 index 00000000..e5f8d24a --- /dev/null +++ b/silk/SKP_Silk_LPC_synthesis_filter.c @@ -0,0 +1,84 @@ +/***********************************************************************
+Copyright (c) 2006-2011, Skype Limited. All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, (subject to the limitations in the disclaimer below)
+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 Skype Limited, nor the names of specific
+contributors, may be used to endorse or promote products derived from
+this software without specific prior written permission.
+NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
+BY THIS LICENSE. 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.
+***********************************************************************/
+
+/* *
+ * SKP_Silk_LPC_synthesis_filter.c *
+ * Coefficients are in Q12 *
+ * *
+ * even order AR filter *
+ * */
+#include "SKP_Silk_SigProc_FIX.h"
+
+/* even order AR filter */
+void SKP_Silk_LPC_synthesis_filter(
+ const SKP_int16 *in, /* I: excitation signal */
+ const SKP_int16 *A_Q12, /* I: AR coefficients [Order], between -8_Q0 and 8_Q0 */
+ const SKP_int32 Gain_Q26, /* I: gain */
+ SKP_int32 *S, /* I/O: state vector [Order] */
+ SKP_int16 *out, /* O: output signal */
+ const SKP_int32 len, /* I: signal length */
+ const SKP_int Order /* I: filter order, must be even */
+)
+{
+ SKP_int k, j, idx, Order_half = SKP_RSHIFT( Order, 1 );
+ SKP_int32 SA, SB, out32_Q10, out32;
+
+ /* Order must be even */
+ SKP_assert( 2 * Order_half == Order );
+
+ /* S[] values are in Q14 */
+ for( k = 0; k < len; k++ ) {
+ SA = S[ Order - 1 ];
+ out32_Q10 = 0;
+ for( j = 0; j < ( Order_half - 1 ); j++ ) {
+ idx = SKP_SMULBB( 2, j ) + 1;
+ SB = S[ Order - 1 - idx ];
+ S[ Order - 1 - idx ] = SA;
+ out32_Q10 = SKP_SMLAWB( out32_Q10, SA, A_Q12[ ( j << 1 ) ] );
+ out32_Q10 = SKP_SMLAWB( out32_Q10, SB, A_Q12[ ( j << 1 ) + 1 ] );
+ SA = S[ Order - 2 - idx ];
+ S[ Order - 2 - idx ] = SB;
+ }
+
+ /* unrolled loop: epilog */
+ SB = S[ 0 ];
+ S[ 0 ] = SA;
+ out32_Q10 = SKP_SMLAWB( out32_Q10, SA, A_Q12[ Order - 2 ] );
+ out32_Q10 = SKP_SMLAWB( out32_Q10, SB, A_Q12[ Order - 1 ] );
+ /* apply gain to excitation signal and add to prediction */
+ out32_Q10 = SKP_ADD_SAT32( out32_Q10, SKP_SMULWB( Gain_Q26, in[ k ] ) );
+
+ /* scale to Q0 */
+ out32 = SKP_RSHIFT_ROUND( out32_Q10, 10 );
+
+ /* saturate output */
+ out[ k ] = ( SKP_int16 )SKP_SAT16( out32 );
+
+ /* move result into delay line */
+ S[ Order - 1 ] = SKP_LSHIFT_SAT32( out32_Q10, 4 );
+ }
+}
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