cannam@154: /***********************************************************************
cannam@154: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
cannam@154: Redistribution and use in source and binary forms, with or without
cannam@154: modification, are permitted provided that the following conditions
cannam@154: are met:
cannam@154: - Redistributions of source code must retain the above copyright notice,
cannam@154: this list of conditions and the following disclaimer.
cannam@154: - Redistributions in binary form must reproduce the above copyright
cannam@154: notice, this list of conditions and the following disclaimer in the
cannam@154: documentation and/or other materials provided with the distribution.
cannam@154: - Neither the name of Internet Society, IETF or IETF Trust, nor the
cannam@154: names of specific contributors, may be used to endorse or promote
cannam@154: products derived from this software without specific prior written
cannam@154: permission.
cannam@154: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
cannam@154: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
cannam@154: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
cannam@154: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
cannam@154: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
cannam@154: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
cannam@154: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
cannam@154: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
cannam@154: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
cannam@154: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
cannam@154: POSSIBILITY OF SUCH DAMAGE.
cannam@154: ***********************************************************************/
cannam@154: 
cannam@154: #ifdef HAVE_CONFIG_H
cannam@154: #include "config.h"
cannam@154: #endif
cannam@154: 
cannam@154: #include "SigProc_FIX.h"
cannam@154: 
cannam@154: /* Compute number of bits to right shift the sum of squares of a vector */
cannam@154: /* of int16s to make it fit in an int32                                 */
cannam@154: void silk_sum_sqr_shift(
cannam@154:     opus_int32                  *energy,            /* O   Energy of x, after shifting to the right                     */
cannam@154:     opus_int                    *shift,             /* O   Number of bits right shift applied to energy                 */
cannam@154:     const opus_int16            *x,                 /* I   Input vector                                                 */
cannam@154:     opus_int                    len                 /* I   Length of input vector                                       */
cannam@154: )
cannam@154: {
cannam@154:     opus_int   i, shft;
cannam@154:     opus_uint32 nrg_tmp;
cannam@154:     opus_int32 nrg;
cannam@154: 
cannam@154:     /* Do a first run with the maximum shift we could have. */
cannam@154:     shft = 31-silk_CLZ32(len);
cannam@154:     /* Let's be conservative with rounding and start with nrg=len. */
cannam@154:     nrg  = len;
cannam@154:     for( i = 0; i < len - 1; i += 2 ) {
cannam@154:         nrg_tmp = silk_SMULBB( x[ i ], x[ i ] );
cannam@154:         nrg_tmp = silk_SMLABB_ovflw( nrg_tmp, x[ i + 1 ], x[ i + 1 ] );
cannam@154:         nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft );
cannam@154:     }
cannam@154:     if( i < len ) {
cannam@154:         /* One sample left to process */
cannam@154:         nrg_tmp = silk_SMULBB( x[ i ], x[ i ] );
cannam@154:         nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft );
cannam@154:     }
cannam@154:     silk_assert( nrg >= 0 );
cannam@154:     /* Make sure the result will fit in a 32-bit signed integer with two bits
cannam@154:        of headroom. */
cannam@154:     shft = silk_max_32(0, shft+3 - silk_CLZ32(nrg));
cannam@154:     nrg = 0;
cannam@154:     for( i = 0 ; i < len - 1; i += 2 ) {
cannam@154:         nrg_tmp = silk_SMULBB( x[ i ], x[ i ] );
cannam@154:         nrg_tmp = silk_SMLABB_ovflw( nrg_tmp, x[ i + 1 ], x[ i + 1 ] );
cannam@154:         nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft );
cannam@154:     }
cannam@154:     if( i < len ) {
cannam@154:         /* One sample left to process */
cannam@154:         nrg_tmp = silk_SMULBB( x[ i ], x[ i ] );
cannam@154:         nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft );
cannam@154:     }
cannam@154: 
cannam@154:     silk_assert( nrg >= 0 );
cannam@154: 
cannam@154:     /* Output arguments */
cannam@154:     *shift  = shft;
cannam@154:     *energy = nrg;
cannam@154: }
cannam@154: