#!/usr/bin/octave -qf
% SPDX-FileCopyrightText: 2023 Brian Woods
% SPDX-License-Identifier: GPL-2.0-or-later

% simple octave executable script to generate input files for filter testing

signals = {"impulse", "sine", "cosine", "square"};
signal = NaN;
freq = NaN;
width = NaN;
signednesses = {"unsigned", "signed"};
signedness = NaN;
samples = NaN;

function print_help(signals)
	printf("%s <signal> <freq> <width> <signedess> <samples> <filename>\n", ...
	       program_name());
	printf("where:\n");
	printf("\tsignal: the signal type:");
	for i = 1:length(signals)
		switch(i)
		case 1
			printf(" %s", signals{i})
		otherwise
			printf(", %s", signals{i})
		endswitch
	endfor
	printf("\n");
	printf("\tfreq: freqency in sample length\n");
	printf("\twidth: bit width of the output\n");
	printf("\tsignedness: it is either: signed, unsigned\n");
	printf("\tsamples: how many samples to generate\n");
	printf("\tfilename: output filename\n");
endfunction

% input parsing
arg_list = argv ();

if (nargin != 6)
	printf("Too few or too many arguements given.\n");
	print_help(signals)
	quit;
endif

for i = 1:length(signals)
	if strcmp(arg_list{1},signals{i})
		signal = i;
		break
	endif
endfor
if isnan(signal)
	printf("can't parse <signal>.\n");
	print_help(signals)
	exit;
endif

freq = abs(real(str2double(arg_list{2})));
if isnan(freq)
	printf("Can't parse <freq>.\n");
	print_help(signals)
	exit;
endif

width = abs(floor(real(str2double(arg_list{3}))));
if isnan(width)
	printf("Can't parse <width>.\n");
	print_help(signals)
	exit;
endif

for i = 1:length(signednesses)
	if strcmp(arg_list{4},signednesses{i})
		signedness = i;
		break
	endif
endfor
if isnan(signedness)
	printf("can't parse <signedness>.\n");
	print_help(signals)
	exit;
endif

samples = abs(floor(real(str2double(arg_list{5}))));
if isnan(width)
	printf("Can't parse <width>.\n");
	print_help(signals)
	exit;
endif

filename = arg_list{6};
fid = fopen (filename, "w");
% end input parsing

% calc ranges
if signedness == 1
	range_max = 2**width - 1;
	range_min = 0;
else
	range_max = 2**(width-1) -1;
	%makes things easier not to use the extra negative number
	range_min = -range_max;
endif

% actual singal generation
switch (signal)
case 1  % impulse
	for i = 0:samples-1
		switch (i)
		case 0
			fprintf(fid, "%d\n", range_max);
		otherwise
			fprintf(fid, "%d\n", 0);
		endswitch;
	endfor
case {2, 3} % sine and cosine
	if (signedness == 1)  % unsigned
		sine_amp = range_max/2
		sine_off = sine_amp
	else % signed
		sine_amp = range_max
		sine_off = 0
	endif
	if (signal == 2)
		sine_phase = 0;
	else % cosine needs a phase offset
		sine_phase = pi/2
	endif
	sine_freq = (2*pi)/freq
	for i = 0:samples-1
		fprintf(fid, "%d\n",
		        floor(sine_amp*sin(sine_freq*i+sine_phase)
		              + sine_off +.5));
	endfor
case 4 % square
	freq_half = freq/2;
	for i = 0:samples-1
		period = rem(i, freq);
		if (floor(period/freq_half) == 0) %first half
			fprintf(fid, "%d\n", range_max);
		else
			fprintf(fid, "%d\n", range_min);
		endif
	endfor
otherwise
	printf("can't determine how to generate the signal, exiting\n");
	exit;
endswitch

fclose (fid);