turn LD [I] into a single memcpy

1 files changed, 4 insertions, 6 deletions

diff --git a/src/chip8.rs b/src/chip8.rs
index a48b86a..b245861 100644
--- a/src/chip8.rs
+++ b/src/chip8.rs
@@ -184,15 +184,13 @@ impl Chip8 {
             0xF000 => match opcode & 0x00FF {
                 0x0055 => {
                     eprintln!("LD [I], V{}", x);
-                    for i in 0..=x {
-                        self.memory[self.i as usize + i] = self.v[i];
-                    }
+                    let i = self.i as usize;
+                    self.memory[i..=i + x].copy_from_slice(&self.v[..=x]);
                 }
                 0x0065 => {
                     eprintln!("LD V{}, [I]", x);
-                    for i in 0..=x {
-                        self.v[i] = self.memory[self.i as usize + i];
-                    }
+                    let i = self.i as usize;
+                    self.v[..=x].copy_from_slice(&self.memory[i..=i + x]);
                 }
                 _ => unknown_opcode(opcode),
             },