noise.pl

viterbi译码器的一种fpga实现

#!/usr/bin/perl

sub noise {
    $max = (1 << $soft_dec) - 1;

    $num = int(rand() * 1000);
	if ($same_noise > 0) {
		$same_noise--;
		return $add;
	}

    $add = 0;

#    if ($num > 750) { $add = $max*1/6; }
#    if ($num > 850) { $add = $max*2/6; }
#    if ($num > 950) { $add = $max*3/6; }

#   large noise
	if ($num > 500) { $add = $max*1/6; }
	if ($num > 600) { $add = $max*2/6; }
	if ($num > 750) { $add = $max*3/6; }
	if ($num > 850) { $add = $max*4/6; }
	if ($num > 950) { $add = $max*5/6; }

	$num = rand() * $max;
	$dest = $max - $add;
	$same_noise = 0;
	if ($num < 4 * $dest) { $same_noise = 2 }
	if ($num < 2 * $dest) { $same_noise = 4 }
	if ($num < $dest) { $same_noise = 7 }

#	$same_noise = rand() * 1;
#	$same_noise *= $max - $add;
	$same_noise = int($same_noise);
	# print "same_noise : $same_noise\n";
	# print "noise : $add\n\n";

    $add = int($add);
}

$soft_dec = 3;

while (1) { 
	print noise(), "\n";
}