some bug fixes

src/main.rs

@@ -16,6 +16,7 @@ use nes::cartridge::*;
 use nes::disasm::*;
 use opengl_graphics::OpenGL;
 use log::Level;
+use failure::Error;
 
 use gfx_glyph::{Section, GlyphBrushBuilder,GlyphBrush, Scale};
 use gfx_device_gl::{Resources,Factory};
@@ -25,19 +26,19 @@ const BG_COLOR: [f32; 4] = [0.0, 0.0, 252.0/256.0, 1.0];
 // font options
 const FT_SIZE_PX: f32 = 11.0;
 const FT_COLOR_WHITE: [f32; 4] = [1.0; 4];
-const FT_COLOR_RED: [f32; 4] = [168.0/256.0, 0.0, 32.0/256.0, 1.0];
+const FT_COLOR_RED: [f32; 4] = [168.0/256.0, 32.0/256.0, 0.0, 1.0];
 const FT_COLOR_GREEN: [f32; 4] = [0.0, 168.0/256.0, 0.0, 1.0];
 const FT_LINE_DISTANCE: f32 = FT_SIZE_PX * 0.5;
 lazy_static! {
     static ref FT_SCALE: Scale = Scale::uniform(FT_SIZE_PX);
 }
 
-fn main() {
+fn main() -> Result<(), Error> {
-    simple_logger::init_with_level(Level::Error).unwrap();
+    simple_logger::init_with_level(Level::Debug).unwrap();
    
     let mut bus = MemoryBus::new();
-    let cartridge = Path::new("test_roms/registers.nes");
+    let cartridge = Path::new("test_roms/nestest.nes");
-    let cartridge = Cartridge::new(cartridge).unwrap();
+    let cartridge = Cartridge::new(cartridge)?;
     bus.insert_cartrige(cartridge);
 
     // Load little test program into ram
@@ -55,7 +56,7 @@ fn main() {
     // bus.writew(0xfffc, offset);
 
     // disassemble instructions
-    let disasm = Disasm::disassemble(&bus, 0xe1ff, 0xffff-2).unwrap();
+    let disasm = Disasm::disassemble(&bus, 0xC000, 0xFFFF).unwrap();
     // println!("{:?}", disasm.instructions);
     // return;
     // let disasm = Disasm::disassemble(&[], 0x000).unwrap();
@@ -63,6 +64,8 @@ fn main() {
     // Create and reset CPU 
     let mut cpu: CPU = CPU::new();
     cpu.find_pc_addr(&bus);
+    cpu.regs.pc = 0xC000;
+    // return Ok(());
     // cpu.reset(&bus);
 
     // Prepare window and drawing resources
@@ -115,6 +118,7 @@ fn main() {
             }
         }     
     }
+    Ok(())
 }
 
 fn render(window: &mut PistonWindow, event: &Event,
@@ -220,6 +224,15 @@ fn render_cpu(glyphs: &mut GlyphBrush<Resources, Factory>, cpu: &CPU, offset: [f
                 color: color,
                 ..Section::default()
             });
+        position.0 += 16.0;
+        let color = FT_COLOR_WHITE;
+        glyphs.queue(Section {
+                text: &format!("{:#06x}", cpu.regs.flags),
+                scale: *FT_SCALE,
+                screen_position: position,
+                color: color,
+                ..Section::default()
+            });
 
         let cpu_register_texts = [
             &format!("A: {0:#x} ({0})", cpu.regs.a),
@@ -296,7 +309,7 @@ fn render_memory(glyphs: &mut GlyphBrush<Resources, Factory>, bus: &MemoryBus, o
     }
 
     position_y.1 += FT_LINE_DISTANCE+FT_SIZE_PX * 1.5;
-    for page in (0x6000..0x60FF).step_by(16) {
+    for page in (0x2000..0x20FF).step_by(16) {
         position_y.1 += FT_LINE_DISTANCE + FT_SIZE_PX;
         let mut line = format!("{:#06x}:", page);
         (0u16..16u16).map(|offset| offset + page)

src/nes/bus.rs

@@ -44,14 +44,14 @@ pub trait Clockable {
 // A simple bus giving access to a chunk of memory
 // and the cartrige
 pub struct MemoryBus {
-    ram: [Byte; 0x07ff],  // 2kb
+    ram: [Byte; 0x0800],  // 2kb
     cartrige: Option<Cartridge>
 }
 
 impl MemoryBus {
     pub fn new() -> MemoryBus {
         MemoryBus {
-            ram: [0; 0x07ff],
+            ram: [0; 0x0800],
             cartrige: None,
         }
     }
@@ -65,12 +65,12 @@ impl Memory for MemoryBus {
     
     fn readb(&self, addr: Addr) -> Byte {
         if let Some(cartrige) = &self.cartrige {
-            if CART_ADDR_RANGE[0] <= addr && addr < CART_ADDR_RANGE[1] {
+            if CART_ADDR_RANGE[0] <= addr && addr <= CART_ADDR_RANGE[1] {
                 return cartrige.readb(addr)
             } 
         }
 
-        if RAM_ADDR_RANGE[0] <= addr && addr < RAM_ADDR_RANGE[1] {
+        if RAM_ADDR_RANGE[0] <= addr && addr <= RAM_ADDR_RANGE[1] {
             // Ram is 3x mirrored after 07ff
             return self.ram[(addr & 0x07ff) as usize]
         }
@@ -79,12 +79,12 @@ impl Memory for MemoryBus {
 
     fn writeb(&mut self, addr: Addr, data: Byte) {
         if let Some(cartrige) = &mut self.cartrige {
-            if CART_ADDR_RANGE[0] <= addr && addr < CART_ADDR_RANGE[1] {
+            if CART_ADDR_RANGE[0] <= addr && addr <= CART_ADDR_RANGE[1] {
                 cartrige.writeb(addr, data)
             } 
         }
 
-        if RAM_ADDR_RANGE[0] <= addr && addr < RAM_ADDR_RANGE[1] {
+        if RAM_ADDR_RANGE[0] <= addr && addr <= RAM_ADDR_RANGE[1] {
             // Ram is 3x mirrored after 07ff
             self.ram[(addr & 0x07ff) as usize] = data
         }

src/nes/cartridge.rs

@@ -86,6 +86,8 @@ impl Cartridge {
             id => bail!("Mapper {:04} not supported", id)
         };
 
+
+        debug!("Cartrige loaded. mapper: {:?}", &mapper);
         Ok(Cartridge {
             prg_rom: prg_rom,
             chr_rom: chr_rom,

src/nes/cpu.rs

@@ -136,6 +136,11 @@ impl CPU {
         } 
     }
 
+    fn set_flag_nz(&mut self, val: Byte) {
+        self.set_flag(ZERO, val == 0);
+        self.set_flag(NEGATIVE, (val & 0x80) == 0);
+    }
+
     pub fn get_flag(&self, flag: Byte) -> Byte {
         if self.regs.flags & flag > 0 {
             1
@@ -340,9 +345,8 @@ impl CPU {
         let val = tmp2.0;
         let overflow = tmp1.1 || tmp2.1;
         self.set_flag(CARRY, (val & 0xFF) > 255);
-        self.set_flag(ZERO, val == 0);
-        self.set_flag(NEGATIVE, (val & 0x80) == 1);
         self.set_flag(OVERFLOW, overflow);
+        self.set_flag_nz(val as Byte);
         self.regs.a = val as Byte;
     }
 
@@ -366,25 +370,44 @@ impl CPU {
         unimplemented!()
     }
 
-    fn op_BIT<T: Memory>(&mut self, bus: &T, val: Word) {
+    // bits 7 and 6 of operand are transfered to bit 7 and 6 of SR (N,V);
-        unimplemented!()
+    // the zeroflag is set to the result of operand AND accumulator.
+    fn op_BIT<T: Memory>(&mut self, bus: &T, addr: Word) {
+        let val = self.readb(bus, addr);
+        self.set_flag(OVERFLOW, (val & OVERFLOW) == 1);
+        self.set_flag(NEGATIVE, (val & NEGATIVE) == 1);
+        println!("{:#06x}: {}", addr, val);
+        println!("{}", (val & self.regs.a));
+        self.set_flag(ZERO, (val & self.regs.a) == 0);
     }
 
-    fn op_BMI<T: Memory>(&mut self, bus: &T, val: Word) {
+    // Jump to address
-        unimplemented!()
+    fn jump(&mut self, addr: Addr) {
-    }
-
-    // Branch if 0 flag is set
-    fn op_BNE(&mut self, addr: Word) {
-        if self.get_flag(ZERO) == 0 {
         let old_addr = self.regs.pc;
         self.regs.pc = addr;
         println!("Jumping from {:#x} to {:#x}", old_addr, addr);
     }
+
+
+    // Branch if negative flag is set
+    fn op_BMI<T: Memory>(&mut self, bus: &T, addr: Addr) {
+        if self.get_flag(NEGATIVE) == 1 {
+            self.jump(addr);
+        }
     }
 
-    fn op_BPL<T: Memory>(&mut self, bus: &T, val: Word) {
+    // Branch if 0 flag is set
-        unimplemented!()
+    fn op_BNE(&mut self, addr: Addr) {
+        if self.get_flag(ZERO) == 0 {
+            self.jump(addr);
+        }
+    }
+
+    // Branch if negative flag is unset
+    fn op_BPL<T: Memory>(&mut self, bus: &T, addr: Addr) {
+        if self.get_flag(NEGATIVE) == 0 {
+            self.jump(addr);
+        }
     }
 
     fn op_BRK<T: Memory>(&mut self, bus: &T, val: Word) {
@@ -439,15 +462,13 @@ impl CPU {
     // Decrement X
     fn op_DEX(&mut self) {
         self.regs.x = self.regs.x.wrapping_sub(1);
-        self.set_flag(ZERO, self.regs.x == 0);
+        self.set_flag_nz(self.regs.x);
-        self.set_flag(NEGATIVE, (self.regs.x & 0x80) != 0)
     }
 
     // Decrement Y
     fn op_DEY(&mut self) {
         self.regs.y = self.regs.y.wrapping_sub(1);
-        self.set_flag(ZERO, self.regs.y == 0);
+        self.set_flag_nz(self.regs.y);
-        self.set_flag(NEGATIVE, (self.regs.y & 0x80) != 0)
     }
 
     fn op_EOR<T: Memory>(&mut self, bus: &T, val: Word) {
@@ -458,25 +479,22 @@ impl CPU {
         let val = self.readb(bus, addr);
         let val = val.wrapping_add(1);
         self.writeb(bus, addr, val);
-        self.set_flag(ZERO, val == 0);
+        self.set_flag_nz(val);
-        self.set_flag(NEGATIVE, (val & 0x80) != 0)
     }
 
     fn op_INX<T: Memory>(&mut self, bus: &T) {
         self.regs.x = self.regs.x.wrapping_add(1);
-        self.set_flag(ZERO, self.regs.x == 0);
+        self.set_flag_nz(self.regs.x);
-        self.set_flag(NEGATIVE, (self.regs.x & 0x80) != 0)
     }
 
     fn op_INY<T: Memory>(&mut self, bus: &T) {
         self.regs.y = self.regs.y.wrapping_add(1);
-        self.set_flag(ZERO, self.regs.y == 0);
+        self.set_flag_nz(self.regs.y);
-        self.set_flag(NEGATIVE, (self.regs.y & 0x80) != 0)
     }
 
     // Jump to address (set pc)
     fn op_JMP<T: Memory>(&mut self, bus: &T, addr: Word) {
-        self.regs.pc = addr;
+        self.jump(addr);
     }
 
     // Jump to subroutine (leaves trace on the stack)
@@ -486,31 +504,28 @@ impl CPU {
         self.regs.sp -= 1;
         bus.writeb(STACK_BASE_ADDR + self.regs.sp as Word, (self.regs.pc & 0x00ff) as Byte);
         self.regs.sp -= 1;
-        self.regs.pc = addr;
+        self.jump(addr);
     }
 
     // Read value from addr into A
     fn op_LDA<T: Memory>(&mut self, bus: &T, addr: Word) {
         let val = bus.readb(addr);
         self.regs.a = val;
-        self.set_flag(ZERO, val == 0);
+        self.set_flag_nz(val);
-        self.set_flag(NEGATIVE, (val & 0x80) != 0);
     }
 
     // Read value from addr into X
     fn op_LDX<T: Memory>(&mut self, bus: &T, addr: Word) {
         let val = bus.readb(addr);
         self.regs.x = val;
-        self.set_flag(ZERO, val == 0);
+        self.set_flag_nz(val);
-        self.set_flag(NEGATIVE, (val & 0x80) != 0);
     }
 
     // Read value from addr into Y
     fn op_LDY<T: Memory>(&mut self, bus: &T, addr: Word) {
         let val = bus.readb(addr);
         self.regs.y = val;
-        self.set_flag(ZERO, val == 0);
+        self.set_flag_nz(val);
-        self.set_flag(NEGATIVE, (val & 0x80) != 0);
     }
 
     fn op_LSR<T: Memory>(&mut self, bus: &T, val: Word) {
@@ -521,8 +536,9 @@ impl CPU {
         // does nothing
     }
 
-    fn op_ORA<T: Memory>(&mut self, bus: &T, val: Word) {
+    fn op_ORA<T: Memory>(&mut self, bus: &T, addr: Addr) {
-        unimplemented!()
+        self.regs.a |= self.readb(bus, addr);
+        self.set_flag_nz(self.regs.a);
     }
 
     fn op_PHA<T: Memory>(&mut self, bus: &T, val: Word) {
@@ -564,7 +580,12 @@ impl CPU {
     }
 
     fn op_RTS<T: Memory>(&mut self, bus: &T, val: Word) {
-        unimplemented!()
+        self.regs.sp += 1;
+        let lo = bus.readb(0x0100 + self.regs.sp as Addr);
+        self.regs.sp += 1;
+        let hi = bus.readb(0x0100 + self.regs.sp as Addr);
+        let addr = (hi as Addr) << 8 | lo as Addr;
+        self.regs.pc = addr + 1; 
     }
 
     fn op_SBC<T: Memory>(&mut self, bus: &T, val: Word) {

src/nes/disasm.rs

@@ -20,16 +20,22 @@ impl Disasm {
     pub fn disassemble(mem: &MemoryBus, start: Addr, stop: Addr) -> Result<Self, Error> {
         let mut instructions = Vec::new();
         let mut addresses = Vec::new();
-        let mut mem_iter = ((start as usize) .. (stop as usize)+1).map({|a| a as Addr});
+        let mut mem_iter = ((start as usize) .. (stop as usize)).map({|a| a as Addr});
         while let Some(addr) = mem_iter.next() {
+
             let opcode = mem.readb(addr);
             
+            
             // Decode opcode, default to NOP/IMP to "skip" the byte
             let i = Instruction::decode_op(opcode)
                 .unwrap_or(Instruction::decode_op(0xeau8).unwrap()); 
+            
             // debug!("{:?}", i);
             let args = match i.addr_mode {
-                AddrMode::IMM => format!("#{0:02x} ({0})", mem.readb(mem_iter.next().unwrap())),
+                AddrMode::IMM => {
+                    let val = mem.readb(mem_iter.next().unwrap());
+                    format!("#{0:02x} ({0})", val)
+                },
                 AddrMode::ZP0 | AddrMode::ZPX | AddrMode::ZPY  => {
                     let rel_addr = mem.readb(mem_iter.next().unwrap());
                     format!("{:#04x}", rel_addr)
@@ -58,9 +64,13 @@ impl Disasm {
             };
 
             let s = format!("{:#06x}: {} {} ({})", addr, i.operation, args, i.addr_mode);
-            // debug!("{:#06x} {}", addr, &s);
+            // println!("opcode: {:#04x} {:?}", opcode, i);
+            // println!("{}", &s);
+
             instructions.push(s);
             addresses.push(addr);
+
+                        
         }
         Ok(Disasm { start, stop, instructions, addresses })
     }

src/nes/mappers.rs

@@ -16,6 +16,7 @@ pub trait Mapper {
 // Cartrige:
 // 0x4000-0xffff -> first 16K 
 // 0xc000-0xffff -> last 16K or mirror or 0x8000-0xbfff
+#[derive(Debug)]
 pub struct Mapper0 {
     prg_banks: Byte,
     chr_banks: Byte, 
@@ -29,17 +30,23 @@ impl Mapper0 {
 
 impl Mapper for Mapper0 {
     fn map_read_addr(&self, addr: Addr) -> Addr {
+        if 0x8000 <= addr && addr <= 0xFFFF { 
             if self.prg_banks > 1 {
-            addr & 0x7fff
+                return addr & 0x7fff;
             } else {
-            addr & 0x3fff
+                return addr & 0x3fff;
             }
         }
+        0x0000
+    }
     fn map_write_addr(&self, addr: Addr) -> Addr {
+        if 0x8000 <= addr && addr <= 0xFFFF { 
             if self.prg_banks > 1 {
-            addr & 0x7fff
+                return addr & 0x7fff;
             } else {
-            addr & 0x3fff
+                return addr & 0x3fff;
             }
         }
+        0x0000
+    }
 }