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

#include "SigProc_FIX.h"
#include "resampler_private.h"
#include "../celt/stack_alloc.h"

#define ORDER_FIR                   4

/* Downsample by a factor 2/3, low quality */
void silk_resampler_down2_3(
    opus_int32                  *S,                 /* I/O  State vector [ 6 ]                                          */
    opus_int16                  *out,               /* O    Output signal [ floor(2*inLen/3) ]                          */
    const opus_int16            *in,                /* I    Input signal [ inLen ]                                      */
    opus_int32                  inLen               /* I    Number of input samples                                     */
) {
    opus_int32 nSamplesIn, counter, res_Q6;
    VARDECL(opus_int32, buf);
    opus_int32 *buf_ptr;
    SAVE_STACK;

    //    ALLOC( buf, RESAMPLER_MAX_BATCH_SIZE_IN + ORDER_FIR, opus_int32 );
    opus_int32 *buf = (opus_int32*)malloc((RESAMPLER_MAX_BATCH_SIZE_IN + ORDER_FIR) * sizeof(opus_int32));

    /* Copy buffered samples to start of buffer */
    silk_memcpy(buf, S, ORDER_FIR * sizeof(opus_int32));

    /* Iterate over blocks of frameSizeIn input samples */
    while (1) {
        nSamplesIn = silk_min(inLen, RESAMPLER_MAX_BATCH_SIZE_IN);

        /* Second-order AR filter (output in Q8) */
        silk_resampler_private_AR2(&S[ ORDER_FIR ], &buf[ ORDER_FIR ], in,
                                   silk_Resampler_2_3_COEFS_LQ, nSamplesIn);

        /* Interpolate filtered signal */
        buf_ptr = buf;
        counter = nSamplesIn;
        while (counter > 2) {
            /* Inner product */
            res_Q6 = silk_SMULWB(buf_ptr[ 0 ], silk_Resampler_2_3_COEFS_LQ[ 2 ]);
            res_Q6 = silk_SMLAWB(res_Q6, buf_ptr[ 1 ], silk_Resampler_2_3_COEFS_LQ[ 3 ]);
            res_Q6 = silk_SMLAWB(res_Q6, buf_ptr[ 2 ], silk_Resampler_2_3_COEFS_LQ[ 5 ]);
            res_Q6 = silk_SMLAWB(res_Q6, buf_ptr[ 3 ], silk_Resampler_2_3_COEFS_LQ[ 4 ]);

            /* Scale down, saturate and store in output array */
            *out++ = (opus_int16)silk_SAT16(silk_RSHIFT_ROUND(res_Q6, 6));

            res_Q6 = silk_SMULWB(buf_ptr[ 1 ], silk_Resampler_2_3_COEFS_LQ[ 4 ]);
            res_Q6 = silk_SMLAWB(res_Q6, buf_ptr[ 2 ], silk_Resampler_2_3_COEFS_LQ[ 5 ]);
            res_Q6 = silk_SMLAWB(res_Q6, buf_ptr[ 3 ], silk_Resampler_2_3_COEFS_LQ[ 3 ]);
            res_Q6 = silk_SMLAWB(res_Q6, buf_ptr[ 4 ], silk_Resampler_2_3_COEFS_LQ[ 2 ]);

            /* Scale down, saturate and store in output array */
            *out++ = (opus_int16)silk_SAT16(silk_RSHIFT_ROUND(res_Q6, 6));

            buf_ptr += 3;
            counter -= 3;
        }

        in += nSamplesIn;
        inLen -= nSamplesIn;

        if (inLen > 0) {
            /* More iterations to do; copy last part of filtered signal to beginning of buffer */
            silk_memcpy(buf, &buf[ nSamplesIn ], ORDER_FIR * sizeof(opus_int32));
        } else {
            break;
        }
    }

    /* Copy last part of filtered signal to the state for the next call */
    silk_memcpy(S, &buf[ nSamplesIn ], ORDER_FIR * sizeof(opus_int32));
    free(buf);
    RESTORE_STACK;
}
