From 19f31cfbbf19d7df11ebf3ec3b1eb16493dc9298 Mon Sep 17 00:00:00 2001
From: Kevin Hamacher <kevin.hamacher@rub.de>
Date: Wed, 1 Jun 2016 15:02:43 +0200
Subject: [PATCH] Fix some overflows

---
 src/cpu.rs     | 2 +-
 src/display.rs | 2 +-
 src/mbc/mbc.rs | 9 +++++++--
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/cpu.rs b/src/cpu.rs
index 3f72d10..0894e21 100644
--- a/src/cpu.rs
+++ b/src/cpu.rs
@@ -120,7 +120,7 @@ impl CPU {
 
         self.clear_flag(FLAG_N);
         self.set_clear_flag(FLAG_Z, new == 0);
-        self.set_clear_flag(FLAG_C, ((val + c) > 0 && new < old) || (c == 1 && new == old));
+        self.set_clear_flag(FLAG_C, (new < old) || (c == 1 && new == old));
         self.set_clear_flag(FLAG_H, ((old & 0x0F) + (val & 0x0F) + c) > 0x0F);
     }
 
diff --git a/src/display.rs b/src/display.rs
index b7b7a9c..f06e4dd 100644
--- a/src/display.rs
+++ b/src/display.rs
@@ -418,7 +418,7 @@ impl Display {
                             }
 
                             // Draw stuff. We're currently only in monochrome mode
-                            self.set_pixel(x + x_o, render_y, sdl2::pixels::Color::RGB(factor, factor, factor));
+                            self.set_pixel(x.wrapping_add(x_o), render_y, sdl2::pixels::Color::RGB(factor, factor, factor));
 
                         }
                     }
diff --git a/src/mbc/mbc.rs b/src/mbc/mbc.rs
index 84b43af..27e3e2d 100644
--- a/src/mbc/mbc.rs
+++ b/src/mbc/mbc.rs
@@ -20,7 +20,7 @@ impl NoMBC {
 
 impl MBC for NoMBC {
     fn write_byte(&mut self, addr: u16, val: u8) {
-        panic!("Writing not supported for cartridges without MBC.");
+        println!("Writing not supported for cartridges without MBC. (Tried to set {:04X} to {:02X})", addr, val);
     }
 
     fn read_byte(&self, addr: u16) -> u8 {
@@ -30,7 +30,12 @@ impl MBC for NoMBC {
                 // TODO: Check for ram
                 let addr = (addr as usize) - 0xA000;
 
-                self.ram[addr]
+                if addr >= self.ram.len() {
+                    println!("Tried to access {:04X}, however the memory is not present.", addr + 0xA000);
+                    0
+                } else {
+                    self.ram[addr]
+                }
             }
             _ => {
                 panic!("Cartride: Unable to read from {:04X}", addr);