Fix bugs related to 16bit mode, emulation mode and REP instruction

snes-core/src/cpu/cycles.rs

@@ -51,7 +51,7 @@ impl CPU {
             match condition {
                 // Add 1 byte and 1 cycle if m = 0 (16-bit memory/accumulator)
                 Condition::MemorySelectFlag => {
-                    if !self.registers.get_memory_select_flag() {
+                    if self.registers.is_16bit_mode() {
                         cycles += 1;
                         match addressing_mode {
                             A::Immediate => bytes += 1,
@@ -441,6 +441,7 @@ mod cpu_instructions_tests {
     #[test]
     fn test_common_conditions() {
         let mut cpu = CPU::new();
+        cpu.registers.emulation_mode = false;
 
         // 16-bit Memory/accumulator flag condition
         cpu.registers.pc = 0;

snes-core/src/cpu/instructions.rs

@@ -760,7 +760,8 @@ impl CPU {
     }
 
     fn rep(&mut self, bus: &Bus) {
-        self.registers.p = self.get_8bit_from_address(bus, AddressingMode::Immediate);
+        let byte = self.get_8bit_from_address(bus, AddressingMode::Immediate);
+        self.registers.reset_rep_byte(byte);
         self.increment_cycles_rep();
     }
 
@@ -1506,6 +1507,7 @@ mod cpu_instructions_tests {
     fn test_adc() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.a   = 0x0000;
         cpu.registers.pbr = 0x00;
         cpu.registers.pc  = 0x0000;
@@ -1539,6 +1541,7 @@ mod cpu_instructions_tests {
     fn test_sbc() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.a   = 0x0001;
         cpu.registers.pbr = 0x00;
         cpu.registers.pc  = 0x0000;
@@ -1556,6 +1559,7 @@ mod cpu_instructions_tests {
     fn test_and() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.a   = 0x0101;
         cpu.registers.pbr = 0x00;
         cpu.registers.pc  = 0x0000;
@@ -1591,6 +1595,7 @@ mod cpu_instructions_tests {
     fn test_asl() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.a   = 0b01010000_00000000;
         cpu.registers.pbr = 0x00;
         cpu.registers.pc  = 0x0000;
@@ -1608,6 +1613,8 @@ mod cpu_instructions_tests {
     fn test_lsr() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
+        cpu.registers.exposed_bit_zero = ModeFlag::Carry;
         cpu.registers.a   = 0b00000000_00000011;
         cpu.registers.pbr = 0x00;
         cpu.registers.pc  = 0x0000;
@@ -1627,6 +1634,7 @@ mod cpu_instructions_tests {
     fn test_bit() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.a   = 0b1111_0000;
         cpu.registers.pbr = 0x00;
         cpu.registers.pc  = 0x0000;
@@ -2041,6 +2049,7 @@ mod cpu_instructions_tests {
         // store the result nor it affects the overflow flag
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.x   = 0x01;
         cpu.registers.pbr = 0x00;
         cpu.registers.pc  = 0x0000;
@@ -2058,6 +2067,8 @@ mod cpu_instructions_tests {
         cpu.registers.x   = 0x50;
         cpu.registers.pbr = 0x00;
         cpu.registers.pc  = 0x0000;
+        cpu.registers.emulation_mode = false;
+        cpu.registers.exposed_bit_zero = ModeFlag::Carry;
         cpu.registers.set_16bit_index(true);
         cpu.registers.set_overflow_flag(false);
         bus.write(0x000002, 0xB0);
@@ -2077,6 +2088,8 @@ mod cpu_instructions_tests {
         // store the result nor it affects the overflow flag
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
+        cpu.registers.exposed_bit_zero = ModeFlag::Carry;
         cpu.registers.y   = 0x01;
         cpu.registers.pbr = 0x00;
         cpu.registers.pc  = 0x0000;
@@ -2432,6 +2445,7 @@ mod cpu_instructions_tests {
     fn test_phx() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc  = 0x0000;
         cpu.registers.x  = 0x1234;
         cpu.registers.sp  = 0x1FC;
@@ -2447,6 +2461,7 @@ mod cpu_instructions_tests {
     fn test_phy() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc  = 0x0000;
         cpu.registers.y  = 0x1234;
         cpu.registers.sp  = 0x1FC;
@@ -2462,6 +2477,7 @@ mod cpu_instructions_tests {
     fn test_pla() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc  = 0x0000;
         cpu.registers.y  = 0x1234;
         cpu.registers.set_16bit_mode(true);
@@ -2537,6 +2553,7 @@ mod cpu_instructions_tests {
     fn test_plx() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc  = 0x0000;
         cpu.registers.x  = 0x1234;
         cpu.registers.set_16bit_index(true);
@@ -2558,6 +2575,7 @@ mod cpu_instructions_tests {
     fn test_ply() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc  = 0x0000;
         cpu.registers.y  = 0x1234;
         cpu.registers.set_16bit_index(true);
@@ -2579,11 +2597,12 @@ mod cpu_instructions_tests {
     fn test_rep() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc  = 0x0000;
-        cpu.registers.p  = 0x00;
+        cpu.registers.p  = 0xFF;
         bus.write(0x0001, 0xFF);
         cpu.rep(&mut bus);
-        assert_eq!(cpu.registers.p, 0xFF);
+        assert_eq!(cpu.registers.p, 0x00);
         assert_eq!(cpu.registers.pc, 0x0002);
         assert_eq!(cpu.cycles, 3);
     }
@@ -2592,6 +2611,7 @@ mod cpu_instructions_tests {
     fn test_rol() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.set_16bit_mode(false);
         cpu.registers.a  = 0b0100_0000;
         cpu.registers.pc  = 0x0000;
@@ -2607,6 +2627,7 @@ mod cpu_instructions_tests {
     fn test_ror() {
         let mut cpu = CPU::new();
         let mut bus = Bus::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.set_16bit_mode(false);
         cpu.registers.set_carry_flag(true);
         cpu.registers.a  = 0x00;
@@ -2770,6 +2791,7 @@ mod cpu_instructions_tests {
     #[test]
     fn test_tax() {
         let mut cpu = CPU::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc = 0x0000;
         cpu.registers.a = 0xF0F0;
         cpu.registers.x = 0x0000;
@@ -2786,6 +2808,7 @@ mod cpu_instructions_tests {
     #[test]
     fn test_tay() {
         let mut cpu = CPU::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc = 0x0000;
         cpu.registers.a = 0xF0F0;
         cpu.registers.y = 0x0000;
@@ -2850,6 +2873,7 @@ mod cpu_instructions_tests {
     #[test]
     fn test_tsx() {
         let mut cpu = CPU::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc = 0x0000;
         cpu.registers.x = 0x0000;
         cpu.registers.sp = 0xF0F0;
@@ -2863,6 +2887,7 @@ mod cpu_instructions_tests {
     #[test]
     fn test_txa() {
         let mut cpu = CPU::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc = 0x0000;
         cpu.registers.a = 0x0000;
         cpu.registers.x = 0xF0F0;
@@ -2876,6 +2901,7 @@ mod cpu_instructions_tests {
     #[test]
     fn test_txs() {
         let mut cpu = CPU::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc = 0x0000;
         cpu.registers.sp = 0x0000;
         cpu.registers.x = 0xF0F0;
@@ -2889,6 +2915,7 @@ mod cpu_instructions_tests {
     #[test]
     fn test_txy() {
         let mut cpu = CPU::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc = 0x0000;
         cpu.registers.y = 0x0000;
         cpu.registers.x = 0xF0F0;
@@ -2902,6 +2929,7 @@ mod cpu_instructions_tests {
     #[test]
     fn test_tya() {
         let mut cpu = CPU::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc = 0x0000;
         cpu.registers.a = 0x0000;
         cpu.registers.y = 0xF0F0;
@@ -2915,6 +2943,7 @@ mod cpu_instructions_tests {
     #[test]
     fn test_tyx() {
         let mut cpu = CPU::new();
+        cpu.registers.emulation_mode = false;
         cpu.registers.pc = 0x0000;
         cpu.registers.x = 0x0000;
         cpu.registers.y = 0xF0F0;

snes-core/src/cpu/registers.rs

@@ -27,8 +27,8 @@ impl Registers {
             pbr: 0,
             dbr: 0,
             pc: 0,
-            exposed_bit_zero: ModeFlag::Carry,
-            emulation_mode: false,
+            exposed_bit_zero: ModeFlag::EmulationMode,
+            emulation_mode: true,
             carry: false,
         }
     }
@@ -154,10 +154,16 @@ impl Registers {
     }
 
     pub fn is_16bit_index(&self) -> bool {
+        if self.emulation_mode {
+            return false
+        }
         !self.get_index_register_select_flag()
     }
 
     pub fn is_16bit_mode(&self) -> bool {
+        if self.emulation_mode {
+            return false
+        }
         !self.get_memory_select_flag()
     }
 
@@ -223,6 +229,15 @@ impl Registers {
             }
         }
     }
+
+    pub fn reset_rep_byte(&mut self, byte: u8) {
+        self.p = self.p & !byte;
+        // Avoid messing up exposed emu mode flag logic
+        let reset_carry_flag = (byte & 0x01) == 1;
+        if reset_carry_flag {
+            self.set_carry_flag(false);
+        }
+    }
 }
 
 #[cfg(test)]
@@ -232,6 +247,7 @@ mod registers_tests {
     #[test]
     fn test_is_16bit_mode() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.set_memory_select_flag(false);
         assert!(registers.is_16bit_mode());
         registers.set_memory_select_flag(true);
@@ -241,6 +257,7 @@ mod registers_tests {
     #[test]
     fn test_set_16bit_mode() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.set_16bit_mode(true);
         assert!(registers.is_16bit_mode());
         registers.set_16bit_mode(false);
@@ -250,6 +267,7 @@ mod registers_tests {
     #[test]
     fn test_is_16bit_index() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.set_index_register_select_flag(false);
         assert!(registers.is_16bit_index());
         registers.set_index_register_select_flag(true);
@@ -259,6 +277,7 @@ mod registers_tests {
     #[test]
     fn test_set_16bit_index() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.set_16bit_index(true);
         assert!(registers.is_16bit_index());
         registers.set_16bit_index(false);
@@ -268,6 +287,7 @@ mod registers_tests {
     #[test]
     fn test_set_low_a() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.a = 0xA1A1;
         registers.set_low_a(0xFF);
         assert_eq!(registers.a, 0xA1FF);
@@ -276,6 +296,7 @@ mod registers_tests {
     #[test]
     fn test_set_low_x() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.x = 0xA1A1;
         registers.set_low_x(0xFF);
         assert_eq!(registers.x, 0xA1FF);
@@ -284,6 +305,7 @@ mod registers_tests {
     #[test]
     fn test_set_low_y() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.y = 0xA1A1;
         registers.set_low_y(0xFF);
         assert_eq!(registers.y, 0xA1FF);
@@ -292,6 +314,7 @@ mod registers_tests {
     #[test]
     fn test_set_low_sp() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.sp = 0xA1A1;
         registers.set_low_sp(0xFF);
         assert_eq!(registers.sp, 0xA1FF);
@@ -319,6 +342,7 @@ mod registers_tests {
     #[test]
     fn test_status_registers() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.p = 0x00;
 
         registers.set_carry_flag(true);
@@ -388,6 +412,7 @@ mod registers_tests {
     #[test]
     fn test_set_flags() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
 
         registers.p = 0x00;
         registers .set_flags(&[
@@ -411,6 +436,7 @@ mod registers_tests {
     #[test]
     fn test_exchange_carry_and_emulation() {
         let mut registers = Registers::new();
+        registers.emulation_mode = false;
         registers.exposed_bit_zero = ModeFlag::Carry;
         registers .set_flags(&[Flags::Carry(false)]);
         registers.exposed_bit_zero = ModeFlag::EmulationMode;
@@ -433,4 +459,40 @@ mod registers_tests {
         registers.exchange_carry_and_emulation();
         assert_eq!(registers.get_emulation_mode_flag(), false);
     }
+
+    #[test]
+    fn test_reset_rep_byte() {
+        let mut registers = Registers::new();
+        registers.p = 0xFF;
+        registers.reset_rep_byte(0b0000_0001);
+        assert_eq!(registers.p,  0b1111_1110);
+
+        registers.p = 0xFF;
+        registers.reset_rep_byte(0b0000_0010);
+        assert_eq!(registers.p,  0b1111_1101);
+
+        registers.p = 0xFF;
+        registers.reset_rep_byte(0b0010_0010);
+        assert_eq!(registers.p,  0b1101_1101);
+
+        registers.p = 0xFF;
+        registers.reset_rep_byte(0b1111_1111);
+        assert_eq!(registers.p,  0b0000_0000);
+
+        registers.p = 0b0000_0010;
+        registers.reset_rep_byte(0b0000_0001);
+        assert_eq!(registers.p,  0b0000_0010);
+
+        registers.p = 0b0000_0010;
+        registers.reset_rep_byte(0b0000_0010);
+        assert_eq!(registers.p,  0b0000_0000);
+
+        registers.p = 0x38;
+        registers.reset_rep_byte(0x38);
+        assert_eq!(registers.p,  0x00);
+
+        registers.p = 0x86;
+        registers.reset_rep_byte(0x38);
+        assert_eq!(registers.p,  0b10000110);
+    }
 }