#!/usr/bin/perl

$SLASH = 24;
printf "Enter a number or CIDR block size, i.e. 3072 or /24\n";
$lin = readline STDIN;
printf "\n\n";
if (length($lin) == 1 ) {
	printf "You must type either a number of IP addresses or a blocksize\n";
	printf "in CIDR notation, i.e. either 3072 or /24 are valid inputs\n";
	exit(1);
	}
if (substr($lin,0,1) == "/") {
	$Numips = 2 ** (32 - substr($lin,1));
printf "%8d        / This column is the prefix length as used in CIDR slash notation\n", $SLASH;
	}
else { $Numips = $lin; }
	$Eighty = .8 * $Numips;
	$HDR1 = int(exp(.966*log($Numips)));
	$HDR2 = int(exp(.930*log($Numips)));
printf "%8d  Num Ips The number of IP addresses in the specified prefix\n", $Numips;
printf "%8d      80% Number of IP addresses marking the 80% threshold\n", $Eighty;
printf "%8d HDR .966 When the HD Ratio of the block is .966 it refers to this many addresses\n",$HDR1;
printf "%8d HDR .930 When the HD Ratio of the block is .930 it refers to this many addresses\n",$HDR2;
printf "\n";