new file mode 100644
--- /dev/null
+++ b/src/util/prng.rs
@@ -0,0 +1,39 @@
+//! Random number generator extracted from EoSD.
+
+/// Pseudo-random number generator from EoSD.
+#[derive(Debug)]
+pub struct Prng {
+    seed: u16,
+}
+
+impl Prng {
+    /// Create a new pseudo-random number generator from this seed.
+    pub fn new(seed: u16) -> Prng {
+        Prng {
+            seed,
+        }
+    }
+
+    /// Generates a pseudo-random u16.
+    ///
+    /// RE’d from 102h.exe@0x41e780
+    pub fn get_u16(&mut self) -> u16 {
+        let x = ((self.seed ^ 0x9630) - 0x6553) & 0xffff;
+        self.seed = (((x & 0xc000) >> 14) | (x << 2)) & 0xffff;
+        self.seed
+    }
+
+    /// Combines two u16 into a single u32.
+    ///
+    /// RE’d from 102h.exe@0x41e7f0
+    pub fn get_u32(&mut self) -> u32 {
+        ((self.get_u16() as u32) << 16) | self.get_u16() as u32
+    }
+
+    /// Transforms an u32 into a f64.
+    ///
+    /// RE’d from 102h.exe@0x41e820
+    pub fn get_f64(&mut self) -> f64 {
+        self.get_u32() as f64 / (0x100000000u64 as f64)
+    }
+}