PPU: background rendering

Sources/CPU/CPU.swift

@@ -131,6 +131,7 @@ class CPU {
         status = [.interruptDisable, .break2]
 
         programCounter = self.memReadU16(0xFFFC)
+        print(programCounter)
     }
 
     //func loadAndRun(_ program: [UInt8]) {
@@ -150,14 +151,16 @@ class CPU {
     //}
 
     func run() {
-        run(onCycle: {}, onComplete: {})
+        run(onCycle: { print(dumpCpuState(self)) }, onComplete: {})
     }
 
     func run(onCycle: @escaping () -> (), onComplete: @escaping () -> ())  {
         let opcodes = OPCODES_MAP
         while true {
-            if let _nmi = bus.pollNMI() {
+            if bus.pollNMI() != nil {
+                print(programCounter)
                 interrupt(.NMI)
+                print(programCounter)
             }
             processOpcodes(onCycle: onCycle, opcodes: opcodes) {
                 onComplete()

Sources/CPU/Trace.swift

@@ -9,7 +9,7 @@ func dumpCpuState(_ cpu: CPU) -> String {
         {
             let (addr, _) = cpu.getAbsoluteAddress(opcode.mode, addr: cpu.programCounter + 1)
 
-            return (addr, cpu.memRead(addr))
+            return (addr, 0)//cpu.memRead(addr))
         }()
     }
 

Sources/Data/Bus.swift

@@ -3,6 +3,7 @@ class Bus {
     var prgRom: [UInt8]
     var ppu: NesPPU
     var cycles: Int = 0
+    var gameloopCallback: (NesPPU) -> ()
 
     fileprivate let RAM : UInt16 = 0x0000
     fileprivate let RAM_MIRRORS_END: UInt16 = 0x1FFF
@@ -11,18 +12,27 @@ class Bus {
     fileprivate let ROM_ADDRESS_START: UInt16 = 0x8000
     fileprivate let ROM_ADDRESS_END: UInt16 = 0xFFFF
 
-    init(_ rom: Rom) {
+    init(_ rom: Rom, gameloopCallback: @escaping (NesPPU) -> ()) {
         ppu = NesPPU(rom.character, rom.screenMirror)
         self.prgRom = rom.program
+        self.gameloopCallback = gameloopCallback
     }
 
     func tick(_ cycles: UInt8) {
         self.cycles += Int(cycles)
+        let nmiBefore = ppu.nmiInterrupt != nil
+        //print(nmiBefore)
         self.ppu.tick(cycles * 3)
+        let nmiAfter = ppu.nmiInterrupt != nil
+        //print(nmiAfter)
+        if !nmiBefore && nmiAfter {
+            gameloopCallback(ppu)
+        }
+
     }
 
     func pollNMI() -> UInt8? {
-        ppu.nmiInterrupt
+        ppu.pollNMI()
     }
 }
 
@@ -34,13 +44,20 @@ extension Bus: Memory {
             let mirrorDownAddr = addr & 0b00000111_11111111
             return self.cpuVram[Int(mirrorDownAddr)]
         case 0x2000, 0x2001, 0x2003, 0x2005, 0x2006, 0x4014:
-            fatalError("Attempt to read from write-only PPU address \(addr)")
+            //fatalError("Attempt to read from write-only PPU address \(addr)")
+            return 0
         case 0x2002:
             return ppu.readStatus()
         case 0x2004:
             return ppu.readOamData()
         case 0x2007:
             return ppu.readData()
+        case 0x4000...0x4015:
+            return 0 // Ignore APU
+        case 0x4016:
+            return 0 // Ignore Joy 1
+        case 0x4017:
+            return 0 // Ignore Joy 2
         case 0x2008...PPU_REGISTERS_MIRRORS_END:
             let mirrorDownAddr = addr & 0b00100000_00000111;
             return self.memRead(mirrorDownAddr)
@@ -76,6 +93,20 @@ extension Bus: Memory {
         case 0x2008...PPU_REGISTERS_MIRRORS_END:
             let mirrorDownAddr = addr & 0b00100000_00000111
             memWrite(mirrorDownAddr, data: data)
+        case 0x4000...0x4013, 0x4015:
+            return // Ignore APU
+        case 0x4016:
+            return // ignore Joy 1
+        case 0x4017:
+            return // Ignore Joy 2
+        case 0x4014:
+            var buffer = [UInt8](repeating: 0, count: 256)
+            let hi = UInt16(data) << 8
+            for i in 0..<256 {
+                buffer[i] = memRead(hi + UInt16(i))
+            }
+
+            ppu.writeOamDma(buffer)
         case ROM_ADDRESS_START...ROM_ADDRESS_END:
             fatalError("Attempt to write to Cartridge ROM space: \(addr)")
         default:

Sources/PPU/NesPPU.swift

@@ -18,7 +18,7 @@ class NesPPU {
     var scanline: UInt16 = 0
     var cycles: Int = 0
 
-    var nmiInterrupt: UInt8?
+    var nmiInterrupt: UInt8? = nil
 
     init(_ chrRom: [UInt8], _ mirroring: Mirroring) {
         self.chrRom = chrRom
@@ -28,16 +28,16 @@ class NesPPU {
     func tick(_ cycles: UInt8) -> Bool {
         self.cycles += Int(cycles)
         if self.cycles >= 341 {
+            //print(self.cycles)
             self.cycles = self.cycles - 341
-            scanline += 1
+            self.scanline += 1
 
             if scanline == 241 {
-                if self.ctrl.generateVblankNMI() {
-                    self.status.setVblankStatus(true)
-                    status.setSpriteZeroHit(false)
-                    if ctrl.generateVblankNMI() {
-                        nmiInterrupt = 1
-                    }
+                self.status.setVblankStatus(true)
+                status.setSpriteZeroHit(false)
+                if ctrl.generateVblankNMI() {
+                    nmiInterrupt = 1
+                    print("interrupt")
                 }
             }
 
@@ -52,6 +52,12 @@ class NesPPU {
         return false
     }
 
+    func pollNMI() -> UInt8? {
+        let tmp = self.nmiInterrupt
+        self.nmiInterrupt = nil
+        return tmp
+    }
+
     func writeToPPUAddr(_ value: UInt8) {
         addr.update(value)
     }
@@ -109,7 +115,32 @@ class NesPPU {
     }
 
     func writeToData(_ data: UInt8) {
-        fatalError("Not Implemented")
+        let addr = addr.get()
+        print("\(addr): \(data)")
+        switch addr {
+        case 0...0x1fff:
+            print("Attempt to write to chr rom space \(addr)!")
+        case 0x2000...0x2fff:
+            self.vram[Int(mirrorVramAddr(addr))] = data
+        case 0x3000...0x3eff:
+            fatalError("addr \(addr) should not be used in reality!")
+        //Addresses $3F10/$3F14/$3F18/$3F1C are mirrors of $3F00/$3F04/$3F08/$3F0C
+        case 0x3f10, 0x3f14, 0x3f18, 0x3f1c:
+            let addrMirror = addr - 0x10
+            paletteTable[Int(addrMirror - 0x3f00)] = data
+        case 0x3f00...0x3fff:
+            paletteTable[Int(addr - 0x3f00)] = data
+        default:
+            fatalError("Unexpected access to mirrored space \(addr)")
+        }
+        incrememtVramAddr()
+    }
+
+    func writeOamDma(_ buffer: [UInt8]) {
+        for x in buffer {
+            oamData[Int(oamAddr)] = x
+            oamAddr = oamAddr &+ 1
+        }
     }
 
     func readStatus() -> UInt8 {

Sources/PPU/Registers/ControlRegister.swift

@@ -28,7 +28,7 @@ struct ControlRegister: OptionSet {
     static let GENERATE_NMI = ControlRegister(rawValue: 0b10000000)
 
     func vramAddrIncrement() -> UInt8 {
-        if self.contains(.VRAM_ADD_INCREMENT) {
+        if !self.contains(.VRAM_ADD_INCREMENT) {
             1
         } else {
             32
@@ -38,4 +38,12 @@ struct ControlRegister: OptionSet {
     func generateVblankNMI() -> Bool {
         self.contains(.GENERATE_NMI)
     }
+
+    func backgroundPatternAddr() -> Int {
+        if !self.contains(.BACKROUND_PATTERN_ADDR) {
+            0
+        } else {
+            0x1000
+        }
+    }
 }

Sources/Render/Render.swift

@@ -0,0 +1,37 @@
+class Render {
+    static func render(_ ppu: NesPPU, frame: Frame) {
+        let bank = ppu.ctrl.backgroundPatternAddr()
+
+        for i in 0..<0x03c0 { // For now, just use first nametable
+            let tileAddr = UInt16(ppu.vram[i])
+            //print(ppu.vram)
+            let tileX = i % 32
+            let tileY = i / 32
+            let tile = ppu.chrRom[(bank + Int(tileAddr) * 16)...(bank + Int(tileAddr) * 16 + 15)]
+
+            for y in 0...7 {
+                var upper = tile[tile.startIndex + y]
+                var lower = tile[tile.startIndex + y + 8]
+
+                for x in (0...7).reversed() {
+                    let value = (1 & upper) << 1 | (1 & lower)
+                    upper = upper >> 1
+                    lower = lower >> 1
+                    let rgb = switch value {
+                        case 0:
+                            NESColor.SYSTEM_PALLETE[0x01]
+                        case 1:
+                            NESColor.SYSTEM_PALLETE[0x23]
+                        case 2:
+                            NESColor.SYSTEM_PALLETE[0x28]
+                        case 3:
+                            NESColor.SYSTEM_PALLETE[0x31]
+                        default:
+                            fatalError("Invalid Pallete Color type")
+                    }
+                    frame.setPixel((tileX * 8 + x, tileY * 8 + y), rgb)
+                }
+            }
+        }
+    }
+}

Sources/main.swift

@@ -100,14 +100,13 @@ bytes.getBytes(&gameCode, length: bytes.length)
 
 let rom = try Rom(gameCode)
 
-//let tileFrame = TileViewer.showTile(chrRom: rom.character, bank: 1, tileNum: 0)
-let tileFrame = TileViewer.showTileBank(chrRom: rom.character, bank: 1)
+var frame = Frame()
+let bus = Bus(rom) { ppu in
+    Render.render(ppu, frame: frame)
+    SDL_UpdateTexture(texture, nil, frame.data, 256 * 3)
+    SDL_RenderCopy(canvas, texture, nil, nil)
+    SDL_RenderPresent(canvas)
 
-SDL_UpdateTexture(texture, nil, tileFrame.data, 256 * 3)
-SDL_RenderCopy(canvas, texture, nil, nil)
-SDL_RenderPresent(canvas)
-
-while true {
     while SDL_PollEvent(&event) > 0 {
         if event.type == SDL_QUIT.rawValue {
              SDL_DestroyWindow(window)
@@ -127,6 +126,37 @@ while true {
     }
 }
 
+let cpu = CPU(bus: bus)
+cpu.reset()
+cpu.run()
+
+// let tileFrame = TileViewer.showTile(chrRom: rom.character, bank: 1, tileNum: 0)
+// let tileFrame = TileViewer.showTileBank(chrRom: rom.character, bank: 1)
+
+// SDL_UpdateTexture(texture, nil, tileFrame.data, 256 * 3)
+// SDL_RenderCopy(canvas, texture, nil, nil)
+// SDL_RenderPresent(canvas)
+
+// while true {
+//     while SDL_PollEvent(&event) > 0 {
+//         if event.type == SDL_QUIT.rawValue {
+//              SDL_DestroyWindow(window)
+//              SDL_Quit()
+//              exit(0)
+//          }
+//         if event.type == SDL_KEYDOWN.rawValue {
+//             switch SDL_KeyCode(UInt32(event.key.keysym.sym)) {
+//             case SDLK_ESCAPE:
+//                 SDL_DestroyWindow(window)
+//                 SDL_Quit()
+//                 exit(0)
+//             default:
+//                 continue
+//             }
+//         }
+//     }
+// }
+
 // let bus = Bus(try! Rom(gameCode))
 
 //var cpu = CPU(bus: bus)