ref: 81592731016180584d0de28be13965aa5b80ea0d
dir: /src/SKP_Silk_resample_2_3_coarsest.c/
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/* *
* File Name: SKP_Silk_resample_2_3_coarsest.c *
* *
* Description: Linear phase FIR polyphase implementation of resampling *
* *
* Copyright 2009 (c), Skype Limited *
* All rights reserved. *
* *
* Date: 090423 *
* */
#include "SKP_Silk_SigProc_FIX.h"
#include "SKP_Silk_resample_rom.h"
/* Resamples input data with a factor 2/3 */
void SKP_Silk_resample_2_3_coarsest(
SKP_int16 *out, /* O: Output signal */
SKP_int16 *S, /* I/O: Resampler state [ SigProc_Resample_2_3_coarsest_NUM_FIR_COEFS - 1 ] */
const SKP_int16 *in, /* I: Input signal */
const SKP_int frameLenIn, /* I: Number of input samples */
SKP_int16 *scratch /* I: Scratch memory [ frameLenIn + SigProc_Resample_2_3_coarsest_NUM_FIR_COEFS - 1 ] */
)
{
SKP_int32 n, ind, interpol_ind, tmp, index_Q16;
SKP_int16 *in_ptr;
SKP_int frameLenOut;
const SKP_int16 *interpol_ptr;
#if ( EMBEDDED_ARM>=6 ) && defined (__GNUC__)
SKP_int32 in_val, interpol_val;
#endif
/* Copy buffered samples to start of scratch */
SKP_memcpy( scratch, S, ( SigProc_Resample_2_3_coarsest_NUM_FIR_COEFS - 1 ) * sizeof( SKP_int16 ) );
/* Then append by the input signal */
SKP_memcpy( &scratch[ SigProc_Resample_2_3_coarsest_NUM_FIR_COEFS - 1 ], in, frameLenIn * sizeof( SKP_int16 ) );
frameLenOut = SKP_SMULWB( SKP_LSHIFT( (SKP_int32)frameLenIn, 1 ), 21846 ); // 21846_Q15 = (2/3)_Q0 rounded _up_
index_Q16 = 0;
SKP_assert( frameLenIn == ( ( frameLenOut * 3 ) / 2 ) );
/* Interpolate */
for( n = frameLenOut; n > 0; n-- ) {
/* Integer part */
ind = SKP_RSHIFT( index_Q16, 16 );
/* Pointer to buffered input */
in_ptr = scratch + ind;
/* Fractional part */
interpol_ind = ( SKP_SMULWB( index_Q16, SigProc_Resample_2_3_coarsest_NUM_INTERPOLATORS ) &
( SigProc_Resample_2_3_coarsest_NUM_INTERPOLATORS - 1 ) );
/* Pointer to FIR taps */
interpol_ptr = SigProc_Resample_2_3_coarsest_INTERPOL[ interpol_ind ];
/* Interpolate: Hardcoded for 10 FIR taps */
#if ( EMBEDDED_ARM>=6 ) && defined (__GNUC__) /*It doesn't improve efficiency on iphone.*/
/*tmp = SKP_SMUAD( *((SKP_int32 *)interpol_ptr)++, *((SKP_int32 *)in_ptr)++);
tmp = SKP_SMLAD( tmp, *((SKP_int32 *)interpol_ptr)++, *((SKP_int32 *)in_ptr)++);
tmp = SKP_SMLAD( tmp, *((SKP_int32 *)interpol_ptr), *((SKP_int32 *)in_ptr) );*/
__asm__ __volatile__ ( "ldr %1, [%3], #4 \n\t"
"ldr %2, [%4], #4 \n\t"
"smuad %0, %1, %2 \n\t"
"ldr %1, [%3], #4 \n\t"
"ldr %2, [%4], #4 \n\t"
"smlad %0, %1, %2, %0\n\t"
"ldr %1, [%3], #4 \n\t"
"ldr %2, [%4], #4 \n\t"
"smlad %0, %1, %2, %0\n\t"
"ldr %1, [%3], #4 \n\t"
"ldr %2, [%4], #4 \n\t"
"smlad %0, %1, %2, %0\n\t"
"ldr %1, [%3] \n\t"
"ldr %2, [%4] \n\t"
"smlad %0, %1, %2, %0\n\t"
: "=r" (tmp), "=r" (interpol_val), "=r" (in_val), "=r" (interpol_ptr), "=r" (in_ptr)
: "3" (interpol_ptr), "4" (in_ptr));
#else
SKP_assert( SigProc_Resample_2_3_coarsest_NUM_FIR_COEFS == 10 );
tmp = SKP_SMULBB( interpol_ptr[ 0 ], in_ptr[ 0 ] );
tmp = SKP_SMLABB( tmp, interpol_ptr[ 1 ], in_ptr[ 1 ] );
tmp = SKP_SMLABB( tmp, interpol_ptr[ 2 ], in_ptr[ 2 ] );
tmp = SKP_SMLABB( tmp, interpol_ptr[ 3 ], in_ptr[ 3 ] );
tmp = SKP_SMLABB( tmp, interpol_ptr[ 4 ], in_ptr[ 4 ] );
tmp = SKP_SMLABB( tmp, interpol_ptr[ 5 ], in_ptr[ 5 ] );
tmp = SKP_SMLABB( tmp, interpol_ptr[ 6 ], in_ptr[ 6 ] );
tmp = SKP_SMLABB( tmp, interpol_ptr[ 7 ], in_ptr[ 7 ] );
tmp = SKP_SMLABB( tmp, interpol_ptr[ 8 ], in_ptr[ 8 ] );
tmp = SKP_SMLABB( tmp, interpol_ptr[ 9 ], in_ptr[ 9 ] );
#endif
/* Round, saturate and store to output array */
*out++ = (SKP_int16)SKP_SAT16( SKP_RSHIFT_ROUND( tmp, 15 ) );
/* Update index */
index_Q16 += ( ( 1 << 16 ) + ( 1 << 15 ) ); // (3/2)_Q0;
}
/* Move last part of input signal to the sample buffer to prepare for the next call */
SKP_memcpy( S, &in[ frameLenIn - ( SigProc_Resample_2_3_coarsest_NUM_FIR_COEFS - 1 ) ],
( SigProc_Resample_2_3_coarsest_NUM_FIR_COEFS - 1 ) * sizeof( SKP_int16 ) );
}