fix substraction issue

snes-core/src/cpu/instructions/adc.rs

@@ -147,6 +147,25 @@ mod cpu_instructions_tests {
         assert_eq!(registers.pc, 0x02);
         assert_eq!(registers.cycles, 2);
         assert!(!registers.get_carry_flag());
+
+        let mut registers = Registers::new();
+        let mut bus = Bus::new();
+        registers.emulation_mode = false;
+        registers.a   = 0x007F;
+        registers.pbr = 0x00;
+        registers.pc  = 0x0000;
+        registers.set_16bit_mode(false);
+        registers.set_carry_flag(true);
+        bus.write(0x000001, 0x7F);
+        let instruction = ADC8BIN{addressing_mode: AddressingMode::Immediate};
+        instruction.execute(&mut registers, &mut bus);
+        assert_eq!(registers.a, 0xFF);
+        assert_eq!(registers.pc, 0x02);
+        assert_eq!(registers.cycles, 2);
+        assert!(registers.get_negative_flag());
+        assert!(registers.get_overflow_flag());
+        assert!(!registers.get_zero_flag());
+        assert!(!registers.get_carry_flag());
     }
 
     #[test]

snes-core/src/cpu/instructions/cmp.rs

@@ -106,6 +106,7 @@ mod cpu_instructions_tests {
         registers.pc  = 0x0000;
         registers.set_16bit_mode(false);
         registers.set_overflow_flag(false);
+        registers.set_carry_flag(true);
         bus.write(0x000001, 0xB0);
         let instruction = CMP16{addressing_mode: AddressingMode::Immediate};
         instruction.execute(&mut registers, &mut bus);

snes-core/src/cpu/instructions/comp_common.rs

@@ -2,11 +2,13 @@ use crate::{cpu::registers::Registers, utils::{num_trait::SnesNum, alu}, common:
 
 
 pub fn do_comp<T: SnesNum>(registers: &mut Registers, target: T, value: T) {
-    let (_, affected_flags) = alu::sbc_bin(target, value, false);
+    let (_, affected_flags) = alu::sbc_bin(target, value, true);
     for flag in affected_flags {
         match flag {
-            Flags::Overflow(_) => {},
-            _ => registers.set_flags(&[flag]),
+            Flags::Negative(_) |
+            Flags::Zero(_) |
+            Flags::Carry(_) => registers.set_flags(&[flag]),
+            _ => {},
         }
     }
 }

snes-core/src/cpu/instructions/dec_common.rs

@@ -1,7 +1,7 @@
 use crate::{cpu::registers::Registers, utils::{num_trait::SnesNum, alu}, common::flags::Flags};
 
 pub fn do_dec<T: SnesNum>(registers: &mut Registers, target: T) -> T {
-    let (result, affected_flags) = alu::sbc_bin(target, T::from_u32(1), false);
+    let (result, affected_flags) = alu::sbc_bin(target, T::from_u32(1), true);
     for flag in affected_flags {
         match flag {
             Flags::Negative(_) | Flags::Zero(_) => registers.set_flags(&[flag]),

snes-core/src/cpu/instructions/sbc.rs

@@ -139,7 +139,8 @@ mod cpu_instructions_tests {
         registers.a   = 0x0040;
         registers.pbr = 0x00;
         registers.pc  = 0x0000;
-        registers.set_memory_select_flag(true);
+        registers.set_16bit_mode(false);
+        registers.set_carry_flag(true);
         bus.write(0x000001, 0x40);
         let instruction = SBC8BIN{addressing_mode: AddressingMode::Immediate};
         instruction.execute(&mut registers, &mut bus);
@@ -148,6 +149,25 @@ mod cpu_instructions_tests {
         assert_eq!(registers.cycles, 2);
         assert!(registers.get_zero_flag());
         assert!(!registers.get_carry_flag());
+
+        let mut registers = Registers::new();
+        let mut bus = Bus::new();
+        registers.emulation_mode = false;
+        registers.a   = 0x007F;
+        registers.pbr = 0x00;
+        registers.pc  = 0x0000;
+        registers.set_16bit_mode(false);
+        registers.set_carry_flag(false);
+        bus.write(0x000001, 0x7E);
+        let instruction = SBC8BIN{addressing_mode: AddressingMode::Immediate};
+        instruction.execute(&mut registers, &mut bus);
+        assert_eq!(registers.a, 0x00);
+        assert_eq!(registers.pc, 0x02);
+        assert_eq!(registers.cycles, 2);
+        assert!(!registers.get_negative_flag());
+        assert!(!registers.get_overflow_flag());
+        assert!(registers.get_zero_flag());
+        assert!(registers.get_carry_flag());
     }
 
     #[test]
@@ -159,6 +179,7 @@ mod cpu_instructions_tests {
         registers.pbr = 0x00;
         registers.pc  = 0x0000;
         registers.set_memory_select_flag(false);
+        registers.set_carry_flag(true);
         bus.write(0x000001, 0x00);
         bus.write(0x000002, 0x40);
         let instruction = SBC16BIN{addressing_mode: AddressingMode::Immediate};

snes-core/src/cpu/internal_registers.rs

@@ -58,9 +58,6 @@ impl InternalRegisters {
 
     fn read_vblank_nmi_mut(&self, ppu_registers: &mut PPURegisters) -> u8 {
         let result = self.read_vblank_nmi(ppu_registers);
-        if result == 0x80 {
-            println!("nmi set");
-        }
         // When register is read, bit 7 is cleared
         ppu_registers.vblank_nmi = false;
         result

snes-core/src/utils/alu.rs

@@ -49,12 +49,12 @@ pub fn adc_bcd<T: SnesNum>(target: T, value: T, carry: bool) -> (T, [Flags; 4])
 }
 
 pub fn sbc_bin<T: SnesNum>(target: T, value: T, carry: bool) -> (T, [Flags; 4]) {
-    let result = target.sbc_snes(value, carry);
+    let result = target.sbc_snes(value, !carry);
     (result, [
         Negative(result.is_negative()),
         Overflow(target.is_overflow(value, result)),
         Zero(result.is_zero()),
-        Carry(target.sbc_will_carry(value, carry)),
+        Carry(!carry),
     ])
 }
 
@@ -274,33 +274,33 @@ mod alu_tests {
     #[test]
     fn test_dec_bin() {
         // 8 bit
-        let (result, affected_flags) = sbc_bin(1_u8, 1_u8, false);
+        let (result, affected_flags) = sbc_bin(1_u8, 1_u8, true);
         assert_eq!(result, 0);
         assert_eq!(affected_flags, [Negative(false), Overflow(false), Zero(true), Carry(false)]);
 
-        let (result, affected_flags) = sbc_bin(0_u8, 1_u8, false);
+        let (result, affected_flags) = sbc_bin(0_u8, 1_u8, true);
         assert_eq!(result, 0b11111111);
         assert_eq!(affected_flags, [Negative(true), Overflow(true), Zero(false), Carry(true)]);
 
-        let (result, affected_flags) = sbc_bin(0_u8, 1_u8, true);
+        let (result, affected_flags) = sbc_bin(0_u8, 1_u8, false);
         assert_eq!(result, 0b11111110);
         assert_eq!(affected_flags, [Negative(true), Overflow(true), Zero(false), Carry(true)]);
 
         // overflow
-        let (result, affected_flags) = sbc_bin(0x50_u8, 0xB0_u8, false);
+        let (result, affected_flags) = sbc_bin(0x50_u8, 0xB0_u8, true);
         assert_eq!(result, 0xA0);
         assert_eq!(affected_flags, [Negative(true), Overflow(false), Zero(false), Carry(true)]);
         
         // 16 bit
-        let (result, affected_flags) = sbc_bin(1_u16, 1_u16, false);
+        let (result, affected_flags) = sbc_bin(1_u16, 1_u16, true);
         assert_eq!(result, 0);
         assert_eq!(affected_flags, [Negative(false), Overflow(false), Zero(true), Carry(false)]);
 
-        let (result, affected_flags) = sbc_bin(0_u16, 1_u16, false);
+        let (result, affected_flags) = sbc_bin(0_u16, 1_u16, true);
         assert_eq!(result, 0b11111111_11111111);
         assert_eq!(affected_flags, [Negative(true), Overflow(true), Zero(false), Carry(true)]);
 
-        let (result, affected_flags) = sbc_bin(0_u16, 1_u16, true);
+        let (result, affected_flags) = sbc_bin(0_u16, 1_u16, false);
         assert_eq!(result, 0b11111111_11111110);
         assert_eq!(affected_flags, [Negative(true), Overflow(true), Zero(false), Carry(true)]);
     }