Refactor timer

src/bus.rs

@@ -54,14 +54,15 @@ pub const INTERRUPT_FLAG_ADDRESS: u16 = 0xFF0F;
 pub struct Bus {
     game_rom: ROM,
     data: [u8; 0x10000],
+    pub reset_timer: bool,
 }
 
 impl Bus {
     pub fn new() -> Self {
-        let game_rom = match ROM::load_file("ignore/dmg-acid2.gb".to_string()) {
+        // let game_rom = match ROM::load_file("ignore/dr-mario.gb".to_string()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs.gb".to_string()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/01-special.gb".to_string()) {
-        // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/02-interrupts.gb".to_string()) {
+        let game_rom = match ROM::load_file("roms/cpu_instrs_individual/02-interrupts.gb".to_string()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/03-op sp,hl.gb".to_string()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/04-op r,imm.gb".to_string()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/05-op rp.gb".to_string()) {
@@ -101,6 +102,7 @@ impl Bus {
         Self {
             data,
             game_rom,
+            reset_timer: false,
         }
     }
 
@@ -120,6 +122,10 @@ impl Bus {
             // print!("{}", data as char); 
         }
 
+        if address == 0xFF06 {
+            println!("Writing {:02X} to modulo", data);
+        }
+
         if BANK_ZERO.in_range(address) || BANK_SWITCHABLE.in_range(address) {
             // println!("WRITING TO ROM");
         } else if WORK_RAM_1.in_range(address) || WORK_RAM_2.in_range(address) {
@@ -132,13 +138,14 @@ impl Bus {
             self.data[address as usize] = data;
             self.data[(WORK_RAM_1.begin() + (address - ECHO_RAM.begin())) as usize] = data; // Copy to the working RAM
         } else if address == TIMER_DIVIDER_REGISTER_ADDRESS {
-            self.data[address as usize] = 0x00;
+            println!("bus timer reset");
+            self.reset_timer = true;
         } else if address == LCD_CONTROL_ADDRESS && get_bit(data, BitIndex::I7) {
             self.data[address as usize] = data;
             self.data[LCD_Y_ADDRESS as usize] = 0x00;
         } else if address == JOYPAD_ADDRESS {
             let byte = self.data[JOYPAD_ADDRESS as usize];
-            self.data[JOYPAD_ADDRESS as usize] = (data & 0b00110000) | 0b11000000 | (byte & 0b00001111);
+            self.data[JOYPAD_ADDRESS as usize] = (data & 0b11110000) | (byte & 0b00001111);
         } else {
             self.data[address as usize] = data;
         }

src/cpu.rs

@@ -911,13 +911,16 @@ impl CPU {
     }
 
     pub fn handle_interrupt(&mut self, bus: &mut Bus, interrupt: Interrupt) {
-        bus.set_interrupt_enable(interrupt, false);
+        println!("Interrupt: {:?}", interrupt);
         bus.set_interrupt_flag(interrupt, false);
-        let vector = interrupt.get_vector();
+        self.ime = false;
-        self.exec(Opcode::CALL(OpcodeParameter::U16(vector)), bus);
+        self.exec(Opcode::CALL(OpcodeParameter::U16(interrupt.get_vector())), bus);
     }
 
     pub fn check_interrupts(&mut self, bus: &mut Bus) -> Option<Interrupt> {
+        /* println!("IE {:08b}", bus.read(INTERRUPT_ENABLE_ADDRESS));
+        println!("IF {:08b}", bus.read(INTERRUPT_FLAG_ADDRESS));
+        println!("---"); */
         if !self.ime && !self.is_halted {
             return None;
         }
@@ -1809,9 +1812,11 @@ impl CPU {
                 self.registers.increment(Register::PC, 2);
             },
             Opcode::NOP => self.registers.increment(Register::PC, 1),
-            /* Opcode::IllegalInstruction => {panic!("Illegal instruction");},
+            Opcode::IllegalInstruction => {
-            _ => {panic!("Illegal instruction");}, */
+                println!("Illegal instruction!");
-            _ => self.registers.increment(Register::PC, 1),
+                self.registers.increment(Register::PC, 1);
+            },
+            _ => unreachable!(),
         };
     }
 }

src/emulator.rs

@@ -112,6 +112,10 @@ impl Emulator {
         self.cpu.reset_cycles();
         while self.cpu.get_cycles().0 <= cpu_cycles.0 {
             self.cpu.run(&mut self.bus);
+            if self.bus.reset_timer {
+                self.bus.reset_timer = false;
+                self.timer.reset(&mut self.bus);
+            }
             self.ppu.do_cycles(&mut self.bus, self.cpu.get_last_op_cycles());
             self.timer.do_cycles(&mut self.bus, self.cpu.get_last_op_cycles());
         }

src/joypad.rs

@@ -73,8 +73,7 @@ impl Joypad {
         let direction = !get_bit(byte, BitIndex::I4);
         let action = !get_bit(byte, BitIndex::I5);
 
-        let data = 0b11000000 |
+        let data = (byte & 0b11110000) |
-        (byte & 0b00110000) |
         (
             (!((direction && self.down) || (action && self.start)) as u8) << 3
         ) | (

src/ppu.rs

@@ -174,7 +174,6 @@ impl PPU {
     fn check_lyc(bus: &mut Bus) {
         let lyc_compare = PPU::get_lcd_y(bus) == bus.read(LCD_Y_COMPARE_ADDRESS);
         if PPU::get_lcd_status(bus, LCDStatus::LYCInterrupt) && lyc_compare {
-            println!("lyc");
             PPU::set_lcd_status(bus, LCDStatus::LYCFlag, lyc_compare);
             PPU::request_interrupt(bus, Interrupt::LCDSTAT);
         }
@@ -334,24 +333,22 @@ impl PPU {
     }
 
     fn get_palette(index: u8, palette_byte: u8) -> u8 {
-        let index = index & 0b11;
         match index {
             0b00 => palette_byte & 0b11,
             0b01 => (palette_byte >> 2) & 0b11,
             0b10 => (palette_byte >> 4) & 0b11,
             0b11 => (palette_byte >> 6) & 0b11,
-            _ => 0b00,
+            _ => unreachable!(),
         }
     }
 
     fn get_pixel(two_bit_pixel: u8) -> Pixel {
-        let two_bit_pixel = two_bit_pixel & 0b11;
         match two_bit_pixel {
             0b00 => Pixel::White,
             0b01 => Pixel::Light,
             0b10 => Pixel::Dark,
             0b11 => Pixel::Black,
-            _ => Pixel::White,
+            _ => unreachable!(),
         }
     }
 

src/timer.rs

@@ -11,23 +11,23 @@ pub const TIMER_MODULO_ADDRESS: u16           = 0xFF06;
 pub const TIMER_CONTROL_ADDRESS: u16          = 0xFF07;
 
 pub struct Timer {
-    cycles: Cycles,
+    divider: u16,
+    prev_result: bool,
 }
 
 impl Timer {
 
     pub fn new() -> Self {
         Self {
-            cycles: Cycles(0),
+            divider: 0,
+            prev_result: false,
         }
     }
 
-    fn increment_cycles(&mut self, cycles: Cycles) {
+    pub fn reset(&mut self, bus: &mut Bus) {
-        self.cycles.0 += cycles.0;
+        println!("timer reset");
-    }
+        self.divider = 0;
-
+        bus.force_write(TIMER_DIVIDER_REGISTER_ADDRESS, 0);
-    fn reset_cycles(&mut self) {
-        self.cycles.0 = 0;
     }
     
     pub fn do_cycles(&mut self, bus: &mut Bus, cycles: Cycles) {
@@ -39,38 +39,37 @@ impl Timer {
     }
 
     fn cycle(&mut self, bus: &mut Bus) {
-        let div = bus.read(TIMER_DIVIDER_REGISTER_ADDRESS);
+        self.divider = self.divider.wrapping_add(1);
-        bus.write(TIMER_DIVIDER_REGISTER_ADDRESS, div.wrapping_add(1));
+        bus.force_write(TIMER_DIVIDER_REGISTER_ADDRESS, self.divider.to_be_bytes()[0]);
 
-        if Timer::is_timer_enabled(bus) {
+        let result = Timer::is_timer_enabled(bus) && self.get_tima_rate(bus);
-            let tima = bus.read(TIMER_COUNTER_ADDRESS);
+
-            let tima_rate = Timer::get_tima_rate(bus);
+        if self.prev_result && !result {
-            if self.cycles.0 >= tima_rate {
+            let tima = bus.read(TIMER_COUNTER_ADDRESS).wrapping_add(1);
-                if tima.checked_add(1) == None {
+            if tima == 0 {
                 bus.write(TIMER_COUNTER_ADDRESS, bus.read(TIMER_MODULO_ADDRESS));
                 bus.set_interrupt_flag(Interrupt::Timer, true);
+                println!("Timer interrupt set");
             } else {
-                    bus.write(TIMER_COUNTER_ADDRESS, tima.wrapping_add(1));
+                bus.write(TIMER_COUNTER_ADDRESS, tima);
-                }
-                self.reset_cycles();
             }
         }
 
-        self.increment_cycles(Cycles(1));
+        self.prev_result = result;
     }
 
     fn is_timer_enabled(bus: &Bus) -> bool {
         get_bit(bus.read(TIMER_CONTROL_ADDRESS), BitIndex::I2)
     }
 
-    fn get_tima_rate(bus: &Bus) -> usize {
+    fn get_tima_rate(&self, bus: &Bus) -> bool {
         let clock_select = bus.read(TIMER_CONTROL_ADDRESS) & 0b0000_0011;
         match clock_select {
-            0b00 => 16,
+            0b00 => ((self.divider >> 9) & 1) == 1,
-            0b01 => 64,
+            0b01 => ((self.divider >> 3) & 1) == 1,
-            0b10 => 256,
+            0b10 => ((self.divider >> 5) & 1) == 1,
-            0b11 => 1024,
+            0b11 => ((self.divider >> 7) & 1) == 1,
-            _ => 1,
+            _ => unreachable!(),
         }
     }
 }