attempt chatgpt emulator for display

core/src/mos6502cpu.rs

@@ -1,3 +1,4 @@
+use log::trace;
 use crate::address_mode::AddressMode;
 use crate::constants::constants_isa_op::ISA_OP_NOP;
 use crate::instruction::Instruction;
@@ -218,7 +219,7 @@ impl Mos6502Cpu {
                                         }
                                         _ => { 0x00 }
                                     };
-                                    println!("READING FROM MEMORY AT 0x{offset:04x}");
+                                    trace!("READING FROM MEMORY AT 0x{offset:04x}");
                                     self.memory[offset as usize]
                                     // self.peek(offset);
                                 }
@@ -299,7 +300,10 @@ impl Mos6502Cpu {
                         _ => {}
                     }
                 }
-                Operation::JSR => {}
+                Operation::JSR => {
+                    // push pc to stack.
+                    // jump to the subroutine.
+                }
                 Operation::LDA => {
                     match self.oi.mode {
                         AddressMode::Immediate => {
@@ -329,7 +333,6 @@ impl Mos6502Cpu {
                                 _ => {}
                             }
                         }
-                        AddressMode::ZeroPageY => {}
                         AddressMode::Absolute => {
                             if let Operand::Word(offset) = self.ir.operand {
                                 println!("Loading from absolute address 0x{offset:04x}");
@@ -342,7 +345,11 @@ impl Mos6502Cpu {
                                 self.a = self.memory[(offset + self.x as u16) as usize];
                             }
                         }
-                        AddressMode::AbsoluteY => {}
+                        AddressMode::AbsoluteY => {
+                            if let Operand::Word(offset) = self.ir.operand {
+                                self.a = self.memory[(offset + self.y as u16) as usize];
+                            }
+                        }
                         AddressMode::Indirect => {}
                         AddressMode::IndirectX => {}
                         AddressMode::IndirectY => {}
@@ -430,7 +437,16 @@ impl Mos6502Cpu {
                                 }
                             }
                         }
-                        AddressMode::AbsoluteY => {}
+                        AddressMode::AbsoluteY => {
+                            match self.ir.operand {
+                                Operand::Word(offset) => {
+                                    self.memory[(offset + self.y as u16) as usize] = self.a;
+                                }
+                                _ => {
+                                    // Invalid Parameter
+                                }
+                            }
+                        }
                         AddressMode::IndirectX => {}
                         AddressMode::IndirectY => {}
                         _ => {
@@ -600,7 +616,22 @@ mod test {
         cpu.memory[0xbef0] = 0xab;
         cpu.pc = 0x6000;
 
-        for _ in 0..=INSTRUCTION_CYCLES(ISA_OP_LDA_ABS) { cpu.tick(); }
+        for _ in 0..=INSTRUCTION_CYCLES(ISA_OP_LDA_ABSX) { cpu.tick(); }
+
+        assert_eq!(cpu.a, 0xab);
+    }
+
+    #[test]
+    fn lda_absolutey() {
+        let mut cpu = Mos6502Cpu::default();
+        cpu.memory[0x6000] = ISA_OP_LDA_ABSY;
+        cpu.memory[0x6001] = 0xef;
+        cpu.memory[0x6002] = 0xbe;
+        cpu.poke_y(0x01);
+        cpu.memory[0xbef0] = 0xab;
+        cpu.pc = 0x6000;
+
+        for _ in 0..=INSTRUCTION_CYCLES(ISA_OP_LDA_ABSY) { cpu.tick(); }
 
         assert_eq!(cpu.a, 0xab);
     }