DRW now correctly fetches screen coordinates from registers

1 files changed, 3 insertions, 1 deletions

diff --git a/src/chip8.rs b/src/chip8.rs
index 56f111c..eacc1e3 100644
--- a/src/chip8.rs
+++ b/src/chip8.rs
@@ -92,12 +92,14 @@ impl Chip8 {
                 let y = (opcode & 0x00F0) >> 4;
                 let nibble = opcode & 0x000F;
                 eprintln!("DRW V{}, V{}, {}", x, y, nibble);
+                let vx = self.v[x as usize] as u16;
+                let vy = self.v[y as usize] as u16;
                 self.v[0xF] = 0;
                 for yy in 0..nibble {
                     let pixel = self.memory[(self.i + yy) as usize];
                     for xx in 0..8 {
                         if (pixel & (0x80 >> xx)) != 0 {
-                            let si = x + xx + ((y + yy) * WIDTH);
+                            let si = vx + xx + ((vy + yy) * WIDTH);
                             if self.screen[si as usize] == 1 {
                                 self.v[0xF] = 1;
                             }