Added a reference file to notes

.notes/hash.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <stdint.h>
+
+uint32_t hash (uint32_t x) {
+	x = ((x >> 16) ^ x) * 0x45d9f3b;
+	x = ((x >> 16) ^ x) * 0x45d9f3b;
+	x = ((x >> 16) ^ x);
+	return x;
+}
+
+uint32_t unhash ( uint32_t x ) {
+	x = (( x >> 16) ^ x) * 0x119de1f3;
+	x = (( x >> 16) ^ x) * 0x119de1f3;
+	x = (( x >> 16) ^ x);
+	return x;
+}
+
+int main() {
+	//I legit didn't know this algorithm could be reversed. Neat.
+	uint32_t value = 42;
+	printf("%u %u %u", value, hash(value), unhash(hash(value)));
+	return 0;
+}