Add Lehmer32 random number generator

src/lehmer32.cr

@@ -0,0 +1,23 @@
+module PF
+  class Lehmer32
+    include Random
+
+    @state : UInt32
+
+    def initialize(@state = rand(type: UInt32))
+    end
+
+    def new_seed(n : Number)
+      @state = n.to_u32!
+    end
+
+    # Generate the next number in the squence
+    def next_u
+      @state &+= 0xe120fc15
+      tmp : UInt64 = @state.to_u64! &* 0x4a39b70d
+      m1 : UInt32 = ((tmp >> 32) ^ tmp).to_u32!
+      tmp = m1.to_u64! &* 0x12fad5c9
+      ((tmp >> 32) ^ tmp).to_u32!
+    end
+  end
+end