From aaa7b07dd0add847a59fa9f0fd86b068cd7ccb91 Mon Sep 17 00:00:00 2001
From: Samuel Perrouault <samuel.perrouault@gmail.com>
Date: Wed, 26 Mar 2025 20:11:19 +0100
Subject: implement RND Vx, nn

---
 src/chip8.rs | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

(limited to 'src/chip8.rs')

diff --git a/src/chip8.rs b/src/chip8.rs
index faf4c7e..5ff782d 100644
--- a/src/chip8.rs
+++ b/src/chip8.rs
@@ -10,6 +10,27 @@ fn unknown_opcode(opcode: u16) {
     std::process::exit(1);
 }
 
+struct RandomGenerator {
+    random: u8,
+}
+
+impl RandomGenerator {
+    fn new() -> Self {
+        Self { random: 92 }
+    }
+}
+
+impl Iterator for RandomGenerator {
+    type Item = u8;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.random ^= self.random << 6;
+        self.random ^= self.random >> 4;
+        self.random ^= self.random << 1;
+        Some(self.random)
+    }
+}
+
 pub struct Chip8 {
     v: [u8; 16],
     i: u16,
@@ -22,6 +43,7 @@ pub struct Chip8 {
     sound_timer: u8,
     key: [u8; 16],
     draw: bool,
+    random: RandomGenerator,
 }
 
 impl Chip8 {
@@ -38,6 +60,7 @@ impl Chip8 {
             sound_timer: 0,
             key: [0; 16],
             draw: false,
+            random: RandomGenerator::new(),
         }
     }
 
@@ -162,6 +185,10 @@ impl Chip8 {
                 eprintln!("LD I, {}", nnn);
                 self.i = nnn;
             }
+            0xC000 => {
+                eprintln!("RND V{}, {}", x, nn);
+                self.v[x] = self.random.next().unwrap_or(0) & nn;
+            }
             0xD000 => {
                 eprintln!("DRW V{}, V{}, {}", x, y, n);
                 let vx = self.v[x] as u16;
-- 
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