freeswitch/libs/silk/src/SKP_Silk_sum_sqr_shift.c

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/***********************************************************************
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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)
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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.
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- Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of Skype Limited, nor the names of specific
contributors, may be used to endorse or promote products derived from
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this software without specific prior written permission.
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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
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CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
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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,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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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
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
***********************************************************************/
/* *
* SKP_Silk_sum_sqr_shift.c *
* *
* compute number of bits to right shift the sum of squares of a vector *
* of int16s to make it fit in an int32 *
* *
* Copyright 2006-2008 (c), Skype Limited *
* */
#include "SKP_Silk_SigProc_FIX.h"
/* Compute number of bits to right shift the sum of squares of a vector */
/* of int16s to make it fit in an int32 */
void SKP_Silk_sum_sqr_shift(
SKP_int32 *energy, /* O Energy of x, after shifting to the right */
SKP_int *shift, /* O Number of bits right shift applied to energy */
const SKP_int16 *x, /* I Input vector */
SKP_int len /* I Length of input vector */
)
{
SKP_int i, shft;
SKP_int32 in32, nrg_tmp, nrg;
if( (SKP_int32)( (SKP_int_ptr_size)x & 2 ) != 0 ) {
/* Input is not 4-byte aligned */
nrg = SKP_SMULBB( x[ 0 ], x[ 0 ] );
i = 1;
} else {
nrg = 0;
i = 0;
}
shft = 0;
len--;
while( i < len ) {
/* Load two values at once */
in32 = *( (SKP_int32 *)&x[ i ] );
nrg = SKP_SMLABB_ovflw( nrg, in32, in32 );
nrg = SKP_SMLATT_ovflw( nrg, in32, in32 );
i += 2;
if( nrg < 0 ) {
/* Scale down */
nrg = (SKP_int32)SKP_RSHIFT_uint( (SKP_uint32)nrg, 2 );
shft = 2;
break;
}
}
for( ; i < len; i += 2 ) {
/* Load two values at once */
in32 = *( (SKP_int32 *)&x[ i ] );
nrg_tmp = SKP_SMULBB( in32, in32 );
nrg_tmp = SKP_SMLATT_ovflw( nrg_tmp, in32, in32 );
nrg = (SKP_int32)SKP_ADD_RSHIFT_uint( nrg, (SKP_uint32)nrg_tmp, shft );
if( nrg < 0 ) {
/* Scale down */
nrg = (SKP_int32)SKP_RSHIFT_uint( (SKP_uint32)nrg, 2 );
shft += 2;
}
}
if( i == len ) {
/* One sample left to process */
nrg_tmp = SKP_SMULBB( x[ i ], x[ i ] );
nrg = (SKP_int32)SKP_ADD_RSHIFT_uint( nrg, nrg_tmp, shft );
}
/* Make sure to have at least one extra leading zero (two leading zeros in total) */
if( nrg & 0xC0000000 ) {
nrg = SKP_RSHIFT_uint( (SKP_uint32)nrg, 2 );
shft += 2;
}
/* Output arguments */
*shift = shft;
*energy = nrg;
}