emu: Add TXS, TSX

Granddave · Dec 30, 2023 · 0ca0deb · 0ca0deb
1 parent 50d7cc5
commit 0ca0deb
Showing 1 changed file with 40 additions and 0 deletions.
diff --git a/src/emulator/cpu.rs b/src/emulator/cpu.rs
@@ -813,12 +813,20 @@ impl Cpu {
                 return 2;
             }
             // TSX
+            (ASTMnemonic::TSX, _, ASTOperand::Implied) => {
+                self.load_register(Register::X, self.sp);
+                return 2;
+            }
             // TXA
             (ASTMnemonic::TXA, _, ASTOperand::Implied) => {
                 self.load_register(Register::A, self.x);
                 return 2;
             }
             // TXS
+            (ASTMnemonic::TXS, _, ASTOperand::Implied) => {
+                self.sp = self.x;
+                return 2;
+            }
             // TYA
             (ASTMnemonic::TYA, _, ASTOperand::Implied) => {
                 self.load_register(Register::A, self.y);
@@ -2326,6 +2334,38 @@ mod tests {
                 expected_cycles: 2 + 2,
                 ..Default::default()
             },
+            // TSX
+            TestCase {
+                code: "TSX",
+                expected_cpu: Cpu {
+                    x: 0xff,
+                    sp: 0xff,
+                    pc: PROGRAM_START + 1,
+                    status: Status {
+                        negative: true,
+                        ..Default::default()
+                    },
+                    ..Default::default()
+                },
+                expected_cycles: 2,
+                ..Default::default()
+            },
+            // TXS
+            TestCase {
+                code: "LDX #$fc\nTXS",
+                expected_cpu: Cpu {
+                    x: 0xfc,
+                    sp: 0xfc,
+                    pc: PROGRAM_START + 2 + 1,
+                    status: Status {
+                        negative: true,
+                        ..Default::default()
+                    },
+                    ..Default::default()
+                },
+                expected_cycles: 2 + 2,
+                ..Default::default()
+            },
         ]
         .into_iter()
         .for_each(|tc| tc.run_test());