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| products derived from this software without specific prior written |
| permission. |
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| ***********************************************************************/ |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #include "SigProc_FIX.h" |
| |
| /* Compute autocorrelation */ |
| void silk_autocorr( |
| opus_int32 *results, /* O Result (length correlationCount) */ |
| opus_int *scale, /* O Scaling of the correlation vector */ |
| const opus_int16 *inputData, /* I Input data to correlate */ |
| const opus_int inputDataSize, /* I Length of input */ |
| const opus_int correlationCount /* I Number of correlation taps to compute */ |
| ) |
| { |
| opus_int i, lz, nRightShifts, corrCount; |
| opus_int64 corr64; |
| |
| corrCount = silk_min_int( inputDataSize, correlationCount ); |
| |
| /* compute energy (zero-lag correlation) */ |
| corr64 = silk_inner_prod16_aligned_64( inputData, inputData, inputDataSize ); |
| |
| /* deal with all-zero input data */ |
| corr64 += 1; |
| |
| /* number of leading zeros */ |
| lz = silk_CLZ64( corr64 ); |
| |
| /* scaling: number of right shifts applied to correlations */ |
| nRightShifts = 35 - lz; |
| *scale = nRightShifts; |
| |
| if( nRightShifts <= 0 ) { |
| results[ 0 ] = silk_LSHIFT( (opus_int32)silk_CHECK_FIT32( corr64 ), -nRightShifts ); |
| |
| /* compute remaining correlations based on int32 inner product */ |
| for( i = 1; i < corrCount; i++ ) { |
| results[ i ] = silk_LSHIFT( silk_inner_prod_aligned( inputData, inputData + i, inputDataSize - i ), -nRightShifts ); |
| } |
| } else { |
| results[ 0 ] = (opus_int32)silk_CHECK_FIT32( silk_RSHIFT64( corr64, nRightShifts ) ); |
| |
| /* compute remaining correlations based on int64 inner product */ |
| for( i = 1; i < corrCount; i++ ) { |
| results[ i ] = (opus_int32)silk_CHECK_FIT32( silk_RSHIFT64( silk_inner_prod16_aligned_64( inputData, inputData + i, inputDataSize - i ), nRightShifts ) ); |
| } |
| } |
| } |