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//#ifdef HAVE_CONFIG_H
#include "../config.h"
//#endif

#include "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 silk_sum_sqr_shift(
    opus_int32                  *energy,            /* O   Energy of x, after shifting to the right                     */
    opus_int                    *shift,             /* O   Number of bits right shift applied to energy                 */
    const opus_int16            *x,                 /* I   Input vector                                                 */
    opus_int                    len                 /* I   Length of input vector                                       */
) {
    opus_int   i, shft;
    opus_uint32 nrg_tmp;
    opus_int32 nrg;

    /* Do a first run with the maximum shift we could have. */
    shft = 31 - silk_CLZ32(len);
    /* Let's be conservative with rounding and start with nrg=len. */
    nrg  = len;
    for (i = 0; i < len - 1; i += 2) {
        nrg_tmp = silk_SMULBB(x[ i ], x[ i ]);
        nrg_tmp = silk_SMLABB_ovflw(nrg_tmp, x[ i + 1 ], x[ i + 1 ]);
        nrg = (opus_int32)silk_ADD_RSHIFT_uint(nrg, nrg_tmp, shft);
    }
    if (i < len) {
        /* One sample left to process */
        nrg_tmp = silk_SMULBB(x[ i ], x[ i ]);
        nrg = (opus_int32)silk_ADD_RSHIFT_uint(nrg, nrg_tmp, shft);
    }
    silk_assert(nrg >= 0);
    /*  Make sure the result will fit in a 32-bit signed integer with two bits
        of headroom. */
    shft = silk_max_32(0, shft + 3 - silk_CLZ32(nrg));
    nrg = 0;
    for (i = 0 ; i < len - 1; i += 2) {
        nrg_tmp = silk_SMULBB(x[ i ], x[ i ]);
        nrg_tmp = silk_SMLABB_ovflw(nrg_tmp, x[ i + 1 ], x[ i + 1 ]);
        nrg = (opus_int32)silk_ADD_RSHIFT_uint(nrg, nrg_tmp, shft);
    }
    if (i < len) {
        /* One sample left to process */
        nrg_tmp = silk_SMULBB(x[ i ], x[ i ]);
        nrg = (opus_int32)silk_ADD_RSHIFT_uint(nrg, nrg_tmp, shft);
    }

    silk_assert(nrg >= 0);

    /* Output arguments */
    *shift  = shft;
    *energy = nrg;
}

