#!/usr/bin/awk -f

### conv.awk
# [PoC] linear convolution (with hardcoded IR window).

BEGIN {
    OFMT = "%.9g"
    X = ARGV[1]
    input_size = split(X, X_arr)
    #H = "1.0 1.0 1.0"      # rect
    #H = "0.25 0.50 0.25"   # von Hann
    H = "0.23 0.54 0.23"   # Hamming
    window_size = split(H, H_arr)
    output_size = (input_size + window_size - 1)
    for (n=1; n <= output_size; n++) {
        Y_arr[n] = 0
        for (m=1; m <= input_size; m++) {
            if (n <= window_size) {
                Y_arr[n] = Y_arr[n] + H_arr[n-m+1]*X_arr[m]
                continue
            }
            if ((n > window_size) && (n <= input_size)) {
                Y_arr[n] = Y_arr[n] + H_arr[n-m+1]*X_arr[m]
                continue
            }
            if ((n > window_size) && (n > input_size)) {
                Y_arr[n] = Y_arr[n] + H_arr[n-m+1]*X_arr[m]
                continue
            }
            else {
                Y_arr[n] = Y_arr[n] + 0
                continue
            }
        }
        print Y_arr[n]
    }
}