michael@0: /***********************************************************************
michael@0: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
michael@0: Redistribution and use in source and binary forms, with or without
michael@0: modification, are permitted provided that the following conditions
michael@0: are met:
michael@0: - Redistributions of source code must retain the above copyright notice,
michael@0: this list of conditions and the following disclaimer.
michael@0: - Redistributions in binary form must reproduce the above copyright
michael@0: notice, this list of conditions and the following disclaimer in the
michael@0: documentation and/or other materials provided with the distribution.
michael@0: - Neither the name of Internet Society, IETF or IETF Trust, nor the
michael@0: names of specific contributors, may be used to endorse or promote
michael@0: products derived from this software without specific prior written
michael@0: permission.
michael@0: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
michael@0: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
michael@0: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
michael@0: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
michael@0: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
michael@0: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
michael@0: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
michael@0: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
michael@0: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
michael@0: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
michael@0: POSSIBILITY OF SUCH DAMAGE.
michael@0: ***********************************************************************/
michael@0: 
michael@0: #ifdef HAVE_CONFIG_H
michael@0: #include "config.h"
michael@0: #endif
michael@0: 
michael@0: #include "SigProc_FIX.h"
michael@0: 
michael@0: /* Compute number of bits to right shift the sum of squares of a vector */
michael@0: /* of int16s to make it fit in an int32                                 */
michael@0: void silk_sum_sqr_shift(
michael@0:     opus_int32                  *energy,            /* O   Energy of x, after shifting to the right                     */
michael@0:     opus_int                    *shift,             /* O   Number of bits right shift applied to energy                 */
michael@0:     const opus_int16            *x,                 /* I   Input vector                                                 */
michael@0:     opus_int                    len                 /* I   Length of input vector                                       */
michael@0: )
michael@0: {
michael@0:     opus_int   i, shft;
michael@0:     opus_int32 nrg_tmp, nrg;
michael@0: 
michael@0:     nrg  = 0;
michael@0:     shft = 0;
michael@0:     len--;
michael@0:     for( i = 0; i < len; i += 2 ) {
michael@0:         nrg = silk_SMLABB_ovflw( nrg, x[ i ], x[ i ] );
michael@0:         nrg = silk_SMLABB_ovflw( nrg, x[ i + 1 ], x[ i + 1 ] );
michael@0:         if( nrg < 0 ) {
michael@0:             /* Scale down */
michael@0:             nrg = (opus_int32)silk_RSHIFT_uint( (opus_uint32)nrg, 2 );
michael@0:             shft = 2;
michael@0:             break;
michael@0:         }
michael@0:     }
michael@0:     for( ; i < len; i += 2 ) {
michael@0:         nrg_tmp = silk_SMULBB( x[ i ], x[ i ] );
michael@0:         nrg_tmp = silk_SMLABB_ovflw( nrg_tmp, x[ i + 1 ], x[ i + 1 ] );
michael@0:         nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, (opus_uint32)nrg_tmp, shft );
michael@0:         if( nrg < 0 ) {
michael@0:             /* Scale down */
michael@0:             nrg = (opus_int32)silk_RSHIFT_uint( (opus_uint32)nrg, 2 );
michael@0:             shft += 2;
michael@0:         }
michael@0:     }
michael@0:     if( i == len ) {
michael@0:         /* One sample left to process */
michael@0:         nrg_tmp = silk_SMULBB( x[ i ], x[ i ] );
michael@0:         nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft );
michael@0:     }
michael@0: 
michael@0:     /* Make sure to have at least one extra leading zero (two leading zeros in total) */
michael@0:     if( nrg & 0xC0000000 ) {
michael@0:         nrg = silk_RSHIFT_uint( (opus_uint32)nrg, 2 );
michael@0:         shft += 2;
michael@0:     }
michael@0: 
michael@0:     /* Output arguments */
michael@0:     *shift  = shft;
michael@0:     *energy = nrg;
michael@0: }
michael@0: