Tested and fixed all instructions

! something might still be bugged since the test program is failing,
although not in an obvious manner

.gitignore

@@ -1,3 +1,6 @@
 /target
-.log
+*.log
+*.bin
+*.bin.*
+
 

src/bus.rs

@@ -112,3 +112,39 @@ impl Bus {
         }
     }
 }
+
+/// special Bus only used for testing the emulator
+pub struct FileBus {
+    mem: Ram<0x10000>,
+}
+
+impl fmt::Debug for FileBus {
+
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Bus")
+            .field("mem", &self.mem)
+            .finish()
+    }
+}
+
+impl Memory for FileBus {
+
+    fn read_addr(&self, addr: u16) -> u8 {
+        self.mem.read_addr(addr)    //RAM is mirrored 3 times
+    }
+
+    fn write_addr(&mut self, addr: u16, data: u8) {
+        self.mem.write_addr(addr % 0x0800, data)
+    }
+}
+
+impl FileBus {
+
+    pub fn new() -> Self {
+        FileBus {
+            mem: Ram::from_file("6502_functional_test.bin"),
+        }
+    }
+}
+
+

src/cpu.rs

@@ -4,7 +4,7 @@ use log::{debug, error, info, trace, warn};
 use bitflags::bitflags;
 
 use crate::{
-    bus::Bus,
+    bus::FileBus,
     memory::Memory,
 };
 
@@ -17,11 +17,11 @@ trait Input {
 }
 
 trait RInput: Input {
-    fn read(&self, acc: &u8, bus: &Bus) -> u8;
+    fn read<M: Memory>(&self, acc: &u8, bus: &M) -> u8;
 }
 
 trait WInput: Input {
-    fn write(&mut self, acc: &mut u8, bus: &mut Bus, data: u8);
+    fn write<M: Memory>(&mut self, acc: &mut u8, bus: &mut M, data: u8);
 }
 
 trait RWInput: RInput + WInput {}
@@ -33,11 +33,11 @@ impl Input for Accumulator {
 }
 
 impl RInput for Accumulator {
-    fn read(&self, acc: &u8, _bus: &Bus) -> u8 { *acc }
+    fn read<M: Memory>(&self, acc: &u8, _bus: &M) -> u8 { *acc }
 }
 
 impl WInput for Accumulator {
-    fn write(&mut self, acc: &mut u8, _bus: &mut Bus, data: u8) { *acc = data }
+    fn write<M: Memory>(&mut self, acc: &mut u8, _bus: &mut M, data: u8) { *acc = data }
 }
 
 impl RWInput for Accumulator {}
@@ -51,7 +51,7 @@ impl Input for Data {
 }
 
 impl RInput for Data {
-    fn read(&self, _acc: &u8, _bus: &Bus) -> u8 { self.data }
+    fn read<M: Memory>(&self, _acc: &u8, _bus: &M) -> u8 { self.data }
 }
 
 struct MemoryVal {
@@ -64,13 +64,13 @@ impl Input for MemoryVal {
 }
 
 impl RInput for MemoryVal {
-    fn read(&self, _acc: &u8, bus: &Bus) -> u8 {
+    fn read<M: Memory>(&self, _acc: &u8, bus: &M) -> u8 {
         bus.read_addr(self.addr)
     }
 }
 
 impl WInput for MemoryVal {
-    fn write(&mut self, _acc: &mut u8, bus: &mut Bus, data: u8) {
+    fn write<M: Memory>(&mut self, _acc: &mut u8, bus: &mut M, data: u8) {
         bus.write_addr(self.addr, data);
     }
 }
@@ -93,13 +93,13 @@ impl Input for MemoryValExtra {
 }
 
 impl RInput for MemoryValExtra {
-    fn read(&self, _acc: &u8, bus: &Bus) -> u8 {
+    fn read<M: Memory>(&self, _acc: &u8, bus: &M) -> u8 {
         bus.read_addr(self.addr)
     }
 }
 
 impl WInput for MemoryValExtra {
-    fn write(&mut self, _acc: &mut u8, bus: &mut Bus, data: u8) {
+    fn write<M: Memory>(&mut self, _acc: &mut u8, bus: &mut M, data: u8) {
         bus.write_addr(self.addr, data);
 
         self.extra_cycle = true;
@@ -145,7 +145,7 @@ pub struct Cpu {
     pc: u16,
     s: u8,
     p: StatusReg,
-    bus: Bus,
+    bus: FileBus,
 }
 
 impl fmt::Debug for Cpu {
@@ -167,14 +167,20 @@ impl fmt::Debug for Cpu {
 impl Cpu {
 
     pub fn new() -> Self {
+        
+        // read initial PC value from reset vector
+        let bus = FileBus::new();
+        let pc_lo = bus.read_addr(0xFFFC) as u16;
+        let pc_hi = bus.read_addr(0xFFFD) as u16; 
+
         Cpu {
-            a: 1,
+            a: 0,
-            x: 1,       //TODO temporary
+            x: 0,       
-            y: 2,       //TODO temporary
+            y: 0,       
-            pc: 0,      //TODO to be verified
+            pc: (pc_lo | (pc_hi << 8)) + 3,
             s: 0xFD,
-            p: StatusReg::from_bits(0x35).unwrap(),
+            p: StatusReg::from_bits(0x34).unwrap(),
-            bus: Bus::new(),
+            bus,
         }
     }
 
@@ -186,6 +192,13 @@ impl Cpu {
     fn execute(&mut self) {
 
         let opcode = self.read_pc_addr();
+//        if self.pc-1 > 0x36D0 && self.pc-1 < 0x36D8 {
+//            println!("{:#?}", self);
+//        }
+//        if (self.pc-1) != 0x36D8 {
+//            println!("0x{:0>4X}: {:0>2X}", self.pc-1, opcode);
+//        }
+        
         let cycles = parse_opcode!(self, opcode,
             0x69 => adc(mode_immediate),
             0x65 => adc(mode_zero_page),
@@ -296,9 +309,9 @@ impl Cpu {
 
             0xA0 => ldy(mode_immediate),
             0xA4 => ldy(mode_zero_page),
-            0xB4 => ldy(mode_zero_page_y),
+            0xB4 => ldy(mode_zero_page_x),
             0xAC => ldy(mode_absolute),
-            0xBC => ldy(mode_absolute_y),
+            0xBC => ldy(mode_absolute_x),
 
             0x4A => lsr(mode_accumulator),
             0x46 => lsr(mode_zero_page),
@@ -372,10 +385,7 @@ impl Cpu {
             0x8A => txa(mode_implicit),
             0x9A => txs(mode_implicit),
             0x98 => tya(mode_implicit),
-
         );
-
-        info!("0x{:X}: {} cycles", opcode, cycles);
     }
 
     /// Implicit mode 
@@ -411,7 +421,7 @@ impl Cpu {
     /// val = PEEK((arg + X) & 0xFF)
     fn mode_zero_page_x(&mut self) -> MemoryVal {
         MemoryVal {
-            addr: (self.read_pc_addr() + self.x) as u16 & 0x00FF,
+            addr: (self.read_pc_addr().wrapping_add(self.x)) as u16 & 0x00FF,
             cycles: 4,
         }
     }
@@ -421,7 +431,7 @@ impl Cpu {
     /// val = PEEK((arg + Y) & 0xFF)
     fn mode_zero_page_y(&mut self) -> MemoryVal {
         MemoryVal {
-            addr: (self.read_pc_addr() + self.y) as u16 & 0x00FF,
+            addr: (self.read_pc_addr().wrapping_add(self.y)) as u16 & 0x00FF,
             cycles: 4,
         }
     }
@@ -558,8 +568,8 @@ impl Cpu {
     /// Increment PC, then read corresponding value in memory
     fn read_pc_addr(&mut self) -> u8 {
 
-        self.pc += 1;
         let val = self.bus.read_addr(self.pc);
+        self.pc += 1;
 
         val
     }
@@ -692,11 +702,12 @@ impl Cpu {
     fn brk(&mut self, _: ()) -> u32 {
 
         // store PC on stack
-        self.push_stack((self.pc >> 8) as u8);
+        let pc = self.pc.wrapping_add(1);
-        self.push_stack(self.pc as u8);
+        self.push_stack((pc >> 8) as u8);
+        self.push_stack(pc as u8);
         
         // store status register
-        self.p.set(StatusReg::B, true);
+        self.p.set(StatusReg::B | StatusReg::U, true);
         self.push_stack(self.p.bits() as u8);
 
         // load interrupt vector
@@ -743,7 +754,7 @@ impl Cpu {
 
         self.p.set(StatusReg::C, reg >= val);
         self.p.set(StatusReg::Z, reg == val);
-        self.p.set(StatusReg::N, ((reg - val) & (0x1 << 7)) != 0);
+        self.p.set(StatusReg::N, ((reg.wrapping_sub(val)) & (0x1 << 7)) != 0);
 
         input.get_cycles()
     }
@@ -798,8 +809,8 @@ impl Cpu {
 
         // compute
         self.a = (!self.a & val) | (self.a & !val);
-        self.p.set(StatusReg::Z, self.y == 0);
+        self.p.set(StatusReg::Z, self.a == 0);
-        self.p.set(StatusReg::N, (self.y & (0x1 << 7)) != 0);
+        self.p.set(StatusReg::N, (self.a & (0x1 << 7)) != 0);
 
         input.get_cycles()
     }
@@ -809,8 +820,8 @@ impl Cpu {
 
         // compute
         val = val.wrapping_add(1);
-        self.p.set(StatusReg::Z, self.y == 0);
+        self.p.set(StatusReg::Z, val == 0);
-        self.p.set(StatusReg::N, (self.y & (0x1 << 7)) != 0);
+        self.p.set(StatusReg::N, (val & (0x1 << 7)) != 0);
 
          // store result
         input.write(&mut self.a, &mut self.bus, val);
@@ -821,8 +832,8 @@ impl Cpu {
 
         // compute
         self.x = self.x.wrapping_add(1);
-        self.p.set(StatusReg::Z, self.y == 0);
+        self.p.set(StatusReg::Z, self.x == 0);
-        self.p.set(StatusReg::N, (self.y & (0x1 << 7)) != 0);
+        self.p.set(StatusReg::N, (self.x & (0x1 << 7)) != 0);
 
         2
     }
@@ -845,8 +856,9 @@ impl Cpu {
     fn jsr(&mut self, input: MemoryVal) -> u32 {
 
         // store return point
-        self.push_stack((self.pc >> 8) as u8);
+        let pc = self.pc.wrapping_sub(1);
-        self.push_stack(self.pc as u8);
+        self.push_stack((pc >> 8) as u8);
+        self.push_stack(pc as u8);
 
         // load target address
         self.pc = input.addr;
@@ -924,12 +936,18 @@ impl Cpu {
     }
 
     fn php(&mut self, _: ()) -> u32 {
-        self.push_stack(self.p.bits() as u8);
+        let mut p = self.p;
+        p.set(StatusReg::B | StatusReg::U, true);
+        self.push_stack(p.bits() as u8);
         3
     }
 
     fn pla(&mut self, _: ()) -> u32 {
+
         self.a = self.pop_stack();
+        self.p.set(StatusReg::Z, self.a == 0);
+        self.p.set(StatusReg::N, (self.a & (0x1 << 7)) != 0);
+
         4
     }
 
@@ -952,6 +970,10 @@ impl Cpu {
         }
         self.p.set(StatusReg::C, carry);
 
+        // update status bits
+        self.p.set(StatusReg::Z, val == 0);
+        self.p.set(StatusReg::N, (val & (0x1 << 7)) != 0);
+
         // store value
         input.write(&mut self.a, &mut self.bus, val);
         input.get_cycles() + 2
@@ -970,6 +992,10 @@ impl Cpu {
         }
         self.p.set(StatusReg::C, carry);
 
+        // update status bits
+        self.p.set(StatusReg::Z, val == 0);
+        self.p.set(StatusReg::N, (val & (0x1 << 7)) != 0);
+
         // store value
         input.write(&mut self.a, &mut self.bus, val);
         input.get_cycles() + 2
@@ -979,7 +1005,7 @@ impl Cpu {
         
         // load status register (B is cleared and I overrided)
         self.p = StatusReg::from_bits_truncate(self.pop_stack());
-        self.p.set(StatusReg::B, false);
+        self.p.set(StatusReg::B | StatusReg::U, false);
         
         // load pc
         let pc_lo = self.pop_stack() as u16;
@@ -995,6 +1021,7 @@ impl Cpu {
         let pc_lo = self.pop_stack() as u16;
         let pc_hi = self.pop_stack() as u16;
         self.pc = pc_lo | (pc_hi << 8);
+        self.pc = self.pc.wrapping_add(1);
 
         6
     }

src/main.rs

@@ -39,13 +39,15 @@ fn main() -> Result<(), &'static str> {
 
     let vec: Vec<[u8; 4]> = (&buffer).into();
     fb.update_buffer(&vec);
+    let mut update = false;
+    let mut refresh = true;
+    let mut frame_counter = 0;
 
     // event loop
     fb.glutin_handle_basic_input(&mut event_loop, |fb, input| {
         use winit::event::VirtualKeyCode;
 
         // wait for input before updating
-        input.wait = true;
         
         // close if escape is pressed
         if input.key_pressed(VirtualKeyCode::Escape) {
@@ -55,15 +57,43 @@ fn main() -> Result<(), &'static str> {
         // execute next cpu instruction (step mode)
         if input.key_pressed(VirtualKeyCode::S) {
             cpu.tick();
+            refresh = true;
+        }
+
+        if input.key_pressed(VirtualKeyCode::R) {
+            update = true;
+        }
+
+        if input.key_pressed(VirtualKeyCode::C) {
+            update = false;
+            refresh = true; 
+        }
+
+        if update {
+            cpu.tick();
+
+            frame_counter += 1;
+            if frame_counter > 1000 {
+                frame_counter = 0;
+                refresh = true;
+            }
+
+            input.wait = false;
+        } else {
+            input.wait = true;
+        }
+
+        if refresh {
+            refresh = false;
 
             let mut debug_str = String::new();
             write!(debug_str, "{:#?}", cpu).unwrap();
             buffer.fill([20, 20], [760, 560], Pixel::rgba(255, 255, 255, 255));
             renderer.draw(&mut buffer, &debug_str, [20, 20], [760, 560]);
-        }
 
             let vec: Vec<[u8; 4]> = (&buffer).into();
             fb.update_buffer(&vec);
+        }
             
         true
     });

src/memory.rs

@@ -16,17 +16,12 @@ pub struct Ram<const SIZE: usize> {
 impl<const SIZE: usize> fmt::Debug for Ram<SIZE> {
     
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.buffer.iter().enumerate()
+        for i in 0x100..=0x1FF {
-            .try_for_each(|(i, elem)| {
-                if i <= 0xFF {
             if i%0x10 == 0 {
                 f.write_fmt(format_args!("\n    {:0>4X}", i))?;
             }
-                    f.write_fmt(format_args!(" {:0>2X}", elem))
+            f.write_fmt(format_args!(" {:0>2X}", self.buffer[i]))?
-                } else {
-                    Ok(())
         }
-            })?;
             
         Ok(())
     }
@@ -51,4 +46,19 @@ impl<const SIZE: usize> Ram<SIZE> {
             buffer: [0u8; SIZE],
         }
     }
+
+    pub fn from_file(file: &str) -> Self {
+        use std::{
+            fs::File,
+            io::Read,
+        };
+
+        let mut f = File::open(file).unwrap();
+        let mut buffer = [0u8; SIZE];
+        f.read_exact(&mut buffer).unwrap();
+
+        Ram {
+            buffer,
+        }
+    }
 }