implement add_mem_at_hl

pcasaretto · Apr 14, 2024 · 89b4ee0 · 89b4ee0
1 parent 4310591
commit 89b4ee0
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Showing 2 changed files with 136 additions and 3 deletions.
diff --git a/src/instructions/add.rs b/src/instructions/add.rs
@@ -1,4 +1,4 @@
-use crate::cpu::RegisterTarget;
+use crate::cpu::{Register16bTarget, RegisterTarget};
 use crate::gameboy::Gameboy;
 
 pub fn add(target: RegisterTarget) -> impl Fn(&mut Gameboy) -> u8 {
@@ -17,10 +17,25 @@ pub fn add(target: RegisterTarget) -> impl Fn(&mut Gameboy) -> u8 {
     }
 }
 
+pub fn add_mem_at_hl(gameboy: &mut Gameboy) -> u8 {
+    let hl = gameboy.cpu.registers.get_u16(Register16bTarget::HL);
+    let target_value = gameboy.bus.read_byte(hl);
+    let current_value = gameboy.cpu.registers.a;
+    let (new_value, did_overflow) = current_value.overflowing_add(target_value);
+    gameboy.cpu.registers.a = new_value;
+
+    gameboy.cpu.registers.f.carry = did_overflow;
+    gameboy.cpu.registers.f.zero = new_value == 0;
+    gameboy.cpu.registers.f.subtract = false;
+    gameboy.cpu.registers.f.half_carry = (current_value & 0xF) + (target_value & 0xF) > 0xF;
+    const TICKS: u8 = 8;
+    TICKS
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::cpu::{FlagsRegister, Registers, CPU};
+    use crate::cpu::{FlagsRegister, Register16bTarget, Registers, CPU};
 
     #[test]
     fn test_add() {
@@ -132,4 +147,121 @@ mod tests {
         add(RegisterTarget::C)(&mut gameboy);
         assert!(gameboy.cpu.registers.f.half_carry);
     }
+
+    #[test]
+    fn test_add_mem_at_hl() {
+        let mut gameboy = Gameboy {
+            cpu: CPU {
+                registers: Registers {
+                    a: 0,
+                    f: FlagsRegister::from(0),
+                    ..Default::default()
+                },
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        gameboy.cpu.registers.set_u16(Register16bTarget::HL, 0xC050);
+        gameboy.bus.write_byte(0xC050, 1);
+        add_mem_at_hl(&mut gameboy);
+        assert_eq!(gameboy.cpu.registers.a, 1);
+    }
+
+    #[test]
+    fn test_add_mem_at_hl_overflow() {
+        let mut gameboy = Gameboy {
+            cpu: CPU {
+                registers: Registers {
+                    a: 255,
+                    f: FlagsRegister::from(0),
+                    ..Default::default()
+                },
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        gameboy.cpu.registers.set_u16(Register16bTarget::HL, 0xC050);
+        gameboy.bus.write_byte(0xC050, 1);
+        add_mem_at_hl(&mut gameboy);
+        assert_eq!(gameboy.cpu.registers.a, 0);
+    }
+
+    #[test]
+    fn test_add_mem_at_hl_carry_flag() {
+        let mut gameboy = Gameboy {
+            cpu: CPU {
+                registers: Registers {
+                    a: 255,
+                    f: FlagsRegister::from(0),
+                    ..Default::default()
+                },
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        gameboy.cpu.registers.set_u16(Register16bTarget::HL, 0xC050);
+        gameboy.bus.write_byte(0xC050, 1);
+        add_mem_at_hl(&mut gameboy);
+        assert!(gameboy.cpu.registers.f.carry);
+    }
+
+    #[test]
+    fn test_add_mem_at_hl_zero_flag() {
+        let mut gameboy = Gameboy {
+            cpu: CPU {
+                registers: Registers {
+                    a: 0,
+                    f: FlagsRegister::from(0),
+                    ..Default::default()
+                },
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        gameboy.cpu.registers.set_u16(Register16bTarget::HL, 0xC050);
+        gameboy.bus.write_byte(0xC050, 0);
+        add_mem_at_hl(&mut gameboy);
+        assert!(gameboy.cpu.registers.f.zero);
+    }
+
+    #[test]
+    fn test_add_mem_at_hl_substract_flag() {
+        let mut gameboy = Gameboy {
+            cpu: CPU {
+                registers: Registers {
+                    a: 0,
+                    f: FlagsRegister {
+                        subtract: true,
+                        ..Default::default()
+                    },
+                    ..Default::default()
+                },
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        gameboy.cpu.registers.set_u16(Register16bTarget::HL, 0xC050);
+        gameboy.bus.write_byte(0xC050, 1);
+        add_mem_at_hl(&mut gameboy);
+        assert!(!gameboy.cpu.registers.f.subtract);
+    }
+
+    #[test]
+    fn test_add_mem_at_hl_half_carry_flag() {
+        let mut gameboy = Gameboy {
+            cpu: CPU {
+                registers: Registers {
+                    a: 0b00001111,
+                    f: FlagsRegister::from(0),
+                    ..Default::default()
+                },
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+        gameboy.cpu.registers.set_u16(Register16bTarget::HL, 0xC050);
+        gameboy.bus.write_byte(0xC050, 0b0000_0001);
+        add_mem_at_hl(&mut gameboy);
+        assert!(gameboy.cpu.registers.f.half_carry);
+    }
 }
diff --git a/src/instructions/mod.rs b/src/instructions/mod.rs
@@ -185,13 +185,14 @@ pub fn from_byte(byte: u8) -> Box<Instruction> {
         0x7D => Box::new(pai(ld::ld_r_r(RegisterTarget::L, RegisterTarget::A))),
         // 0x7E => Box::new(ld::ld_r_r(RegisterTarget::A, Register16bTarget::HL)),
         0x7F => Box::new(pai(ld::ld_r_r(RegisterTarget::A, RegisterTarget::A))),
-        0x87 => Box::new(pai(add::add(RegisterTarget::A))),
         0x80 => Box::new(pai(add::add(RegisterTarget::B))),
         0x81 => Box::new(pai(add::add(RegisterTarget::C))),
         0x82 => Box::new(pai(add::add(RegisterTarget::D))),
         0x83 => Box::new(pai(add::add(RegisterTarget::E))),
         0x84 => Box::new(pai(add::add(RegisterTarget::H))),
         0x85 => Box::new(pai(add::add(RegisterTarget::L))),
+        0x86 => Box::new(pai(add::add_mem_at_hl)),
+        0x87 => Box::new(pai(add::add(RegisterTarget::A))),
         0x8E => Box::new(pai(adc::adc_mem_at_hl())),
         0x8F => Box::new(pai(adc::adc(RegisterTarget::A))),
         0x88 => Box::new(pai(adc::adc(RegisterTarget::B))),