Adds branching instructions (not tested)

src/r6502/instructions.rs

@@ -551,48 +551,72 @@ impl Instructions
     // BRANCHING
     fn BPL(cpu: &mut R6502, bus: &mut dyn Bus)
     {
-
+        if cpu.check_flag(Flags::N) == 0
+        {
+            cpu.pc += cpu.working_data;
+        }
     }	
 
     fn BMI(cpu: &mut R6502, bus: &mut dyn Bus)
     {
-
+        if cpu.check_flag(Flags::N) != 0
+        {
+            cpu.pc += cpu.working_data;
+        }
     }	
 
     fn BVC(cpu: &mut R6502, bus: &mut dyn Bus)
     {
-
+        if cpu.check_flag(Flags::V) == 0
+        {
+            cpu.pc += cpu.working_data;
+        }
     }	
 
     fn BVS(cpu: &mut R6502, bus: &mut dyn Bus)
     {
-
+        if cpu.check_flag(Flags::V) != 0
+        {
+            cpu.pc += cpu.working_data;
+        }
     }	
 
     fn BCC(cpu: &mut R6502, bus: &mut dyn Bus)
     {
-
+        if cpu.check_flag(Flags::C) == 0
+        {
+            cpu.pc += cpu.working_data;
+        }
     }	
 
     fn BCS(cpu: &mut R6502, bus: &mut dyn Bus)
     {
-
+        if cpu.check_flag(Flags::C) != 0
+        {
+            cpu.pc += cpu.working_data;
+        }
     } 
 
     fn BNE(cpu: &mut R6502, bus: &mut dyn Bus)
     {
-
+        if cpu.check_flag(Flags::Z) == 0
+        {
+            cpu.pc += cpu.working_data;
+        }
     }	
 
     fn BEQ(cpu: &mut R6502, bus: &mut dyn Bus)
     {
-
+        if cpu.check_flag(Flags::Z) != 0
+        {
+            cpu.pc += cpu.working_data;
+        }
     }
 
-    
-
     ///////////////////////////////////////////////////////////
     // INTERRUPT AND SUBROUTINE
 
+    ///////////////////////////////////////////////////////////
+    // SINGLE BYTE
 
 }

src/r6502/mod.rs

@@ -50,7 +50,7 @@ pub struct R6502
     y: u8,      // Y Register
 
     pc: u16,    // Program Counter
-    sp: u8,     // Stack Pointer
+    sp: u16,     // Stack Pointer
     status: u8, // Status Flags
 
     cycles: u32, // Track cycles
@@ -94,7 +94,7 @@ impl R6502
             Registers::Y => self.y = value as u8,
 
             Registers::PC => self.pc = value,
-            Registers::SP => self.sp  = value as u8,
+            Registers::SP => self.sp  = value,
 
             Registers::STATUS => self.status = value as u8,
         }
@@ -121,7 +121,7 @@ impl R6502
         self.a = 0;
         self.x = 0;
         self.y = 0;
-        self.sp = 0xFF;     // stack actually starts at 0x01FF but we only need the low byte since the end of the stack is at 0x0100
+        self.sp = 0x01FF; 
         self.status = 0;
         self.set_flag(Flags::U);
 
@@ -170,6 +170,19 @@ impl R6502
 }
 
 
+fn stack_push(value: u8, cpu: &mut R6502, bus: &mut dyn Bus)
+{
+    // TODO: Check for out of bounds errors
+    bus.write(cpu.sp, value);
+    cpu.sp -= 1;
+}
+
+fn stack_pop(cpu: &mut R6502, bus: &mut dyn Bus) -> u8
+{
+    cpu.sp += 1;
+    bus.read(cpu.sp)
+}
+
 
 fn execute(instruction: u8, cpu: &mut R6502, bus: &mut dyn Bus)
 {
@@ -188,6 +201,8 @@ fn execute(instruction: u8, cpu: &mut R6502, bus: &mut dyn Bus)
         return;
     }
 
+    // Interrupt and Subroutine
+
     // Single byte instructions
     
     // Instructions with arguments
@@ -278,9 +293,13 @@ fn exe_branch(instruction: u8, cpu: &mut R6502, bus: &mut dyn Bus)
 {
     let pc_offset = AddressingModes::REL(cpu, bus);
 
-    // TODO: Decode instruction
+    // Decode instruction
     // Need to map: 10	30	50	70	90	B0 	D0	F0 - op code
     // to:          0   1   2   3   4   5   6   7  - method index
 
     // ChatGPT says: Index = (Value−16​) / 32
+
+    let idx = ((instruction - 16) / 32) as usize;
+
+    Instructions::GROUP_BRANCHING_OPS[idx](cpu, bus);
 }

src/tests/instructions/mod.rs

@@ -658,3 +658,55 @@ fn CPX()
     // Is the Z flag set?
     assert_eq!(1, cpu.check_flag(Flags::Z));
 }
+
+/////////////////////////////////////////////////////////////////////
+//				BRANCHING
+/////////////////////////////////////////////////////////////////////
+
+#[test]
+fn BPL()
+{
+    
+}	
+
+#[test]
+fn BMI()
+{
+
+}	
+
+#[test]
+fn BVC()
+{
+
+}	
+
+#[test]
+fn BVS()
+{
+
+}	
+
+#[test]
+fn BCC()
+{
+
+}	
+
+#[test]
+fn BCS()
+{
+
+} 
+
+#[test]
+fn BNE()
+{
+
+}	
+
+#[test]
+fn BEQ()
+{
+
+}

todo/todo.todo

@@ -59,14 +59,14 @@ Instructions:
         ✔ 111	CPX @done(24-01-10 15:26)
 
     CONDITIONALS:
-        ☐ 10   BPL	
+        ✔ 10   BPL @done(24-01-12 16:49)
-        ☐ 30   BMI	
+        ✔ 30   BMI @done(24-01-12 16:49)
-        ☐ 50   BVC	
+        ✔ 50   BVC @done(24-01-12 16:49)
-        ☐ 70   BVS	
+        ✔ 70   BVS @done(24-01-12 16:49)
-        ☐ 90   BCC	
+        ✔ 90   BCC @done(24-01-12 16:49)
-        ☐ B0   BCS 	
+        ✔ B0   BCS @done(24-01-12 16:49)
-        ☐ D0   BNE	
+        ✔ D0   BNE @done(24-01-12 16:49)
-        ☐ F0   BEQ
+        ✔ F0   BEQ @done(24-01-12 16:49)
 
     INTERRUPT/SUBROUTINE:
         ☐ 00   BRK