float fixed_vector_temp[AMR_SUBFRAME_SIZE];
    memcpy(fixed_vector_temp, p->fixed_vector, AMR_SUBFRAME_SIZE*sizeof(float));
    memset(p->fixed_vector, 0, AMR_SUBFRAME_SIZE*sizeof(float));

    // circularly convolve the fixed vector with the impulse response
    for(j=0; j<AMR_SUBFRAME_SIZE; j++) {
        int index = 0;
        for(i=0; i<AMR_SUBFRAME_SIZE; i++) {
            index = j-i;
            // wrap the index for <0 to make circular convolution
            if(index < 0) index += AMR_SUBFRAME_SIZE;
            p->fixed_vector[j] += fixed_vector_temp[i]*p->ir_filter[j-i];
        }
    }