project09 - snake game functional!

09/Snake/Random.jack

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+/*
+Random Number Generator
+Original author: Taylor Wacker
+Modified by: Connor McKay, Sean O'Connor
+https://gist.github.com/greneholt/2212294
+
+This is a pseudo random number generator that uses the
+Linear Congruential Generator (LCG) to generate random
+numbers.
+*/
+class Random {
+	static int x;
+
+	/*
+	Sets a new seed value.
+	*/
+	function void seed(int seed) {
+		let x = seed;
+		return;
+	}
+
+	/*
+	Returns a mod b. b must be positive.
+	*/
+	function int mod(int a, int b) {
+		if (a < 0) {
+			let a = -a;
+		}
+
+		while ((a + 1) > b) {
+			let a = a - b;
+		}
+
+		return a;
+	}
+
+	/*
+	Returns the next random number. Can be negative or positive.
+	*/
+	function int next() {
+		let x = 7919 + (17*x);
+		return x;
+	}
+
+	/*
+	Returns a random value between x (inclusive) and y (non-inclusive).
+	y must be greater than x.
+	*/
+	function int between(int x, int y) {
+		var int diff;
+		let diff = y - x;
+		return Random.mod(Random.next(), diff) + x;
+	}
+}