PPU: impl scrolling

Sources/Data/Bus.swift

@@ -1,7 +1,8 @@
 class Bus {
     var cpuVram: [UInt8] = .init(repeating: 0, count: 2048)
     var prgRom: [UInt8]
-    var ppu: NesPPU
+    let ppu: NesPPU
+    let joypad1: Joypad
     var cycles: Int = 0
     var gameloopCallback: (NesPPU) -> ()
 
@@ -12,19 +13,20 @@ class Bus {
     fileprivate let ROM_ADDRESS_START: UInt16 = 0x8000
     fileprivate let ROM_ADDRESS_END: UInt16 = 0xFFFF
 
-    init(_ rom: Rom, gameloopCallback: @escaping (NesPPU) -> ()) {
+    init(rom: Rom, joypad1: Joypad, gameloopCallback: @escaping (NesPPU) -> ()) {
         ppu = NesPPU(rom.character, rom.screenMirror)
         self.prgRom = rom.program
         self.gameloopCallback = gameloopCallback
+        self.joypad1 = joypad1
+
     }
 
     func tick(_ cycles: UInt8) {
         self.cycles += Int(cycles)
+
         let nmiBefore = ppu.nmiInterrupt != nil
-        //print(nmiBefore)
-        self.ppu.tick(cycles * 3)
+        _ = self.ppu.tick(cycles * 3)
         let nmiAfter = ppu.nmiInterrupt != nil
-        //print(nmiAfter)
         if !nmiBefore && nmiAfter {
             gameloopCallback(ppu)
         }
@@ -55,7 +57,7 @@ extension Bus: Memory {
         case 0x4000...0x4015:
             return 0 // Ignore APU
         case 0x4016:
-            return 0 // Ignore Joy 1
+            return joypad1.read()
         case 0x4017:
             return 0 // Ignore Joy 2
         case 0x2008...PPU_REGISTERS_MIRRORS_END:
@@ -96,7 +98,7 @@ extension Bus: Memory {
         case 0x4000...0x4013, 0x4015:
             return // Ignore APU
         case 0x4016:
-            return // ignore Joy 1
+            joypad1.write(data)
         case 0x4017:
             return // Ignore Joy 2
         case 0x4014:

Sources/Joypad.swift

@@ -0,0 +1,44 @@
+struct JoypadButton: OptionSet {
+    var rawValue: UInt8
+
+    static let RIGHT = JoypadButton(rawValue: 0b10000000)
+    static let LEFT = JoypadButton(rawValue: 0b01000000)
+    static let DOWN = JoypadButton(rawValue: 0b00100000)
+    static let UP = JoypadButton(rawValue: 0b00010000)
+    static let START = JoypadButton(rawValue: 0b00001000)
+    static let SELECT = JoypadButton(rawValue: 0b00000100)
+    static let BUTTON_B = JoypadButton(rawValue: 0b00000010)
+    static let BUTTON_A = JoypadButton(rawValue: 0b00000001)
+}
+
+class Joypad {
+    var strobe = false
+    var buttonIndex: UInt8 = 0
+    var buttonStatus = JoypadButton()
+
+    func write(_ data: UInt8) {
+        strobe = data & 1 == 1
+        if strobe {
+            buttonIndex = 0
+        }
+    }
+
+    func read() -> UInt8 {
+        if buttonIndex > 7 {
+            return 1
+        }
+        let response = (buttonStatus.rawValue & (1 << buttonIndex)) >> buttonIndex
+        if !strobe {
+            buttonIndex += 1
+        }
+        return response
+    }
+
+    func setButton(_ button: JoypadButton, pressed: Bool) {
+        if pressed {
+            buttonStatus.insert(button)
+        } else {
+            buttonStatus.remove(button)
+        }
+    }
+}

Sources/PPU/NesPPU.swift

@@ -28,6 +28,9 @@ class NesPPU {
     func tick(_ cycles: UInt8) -> Bool {
         self.cycles += Int(cycles)
         if self.cycles >= 341 {
+            if checkSprite0Hit(self.cycles) {
+                status.setSpriteZeroHit(true)
+            }
             self.cycles = self.cycles - 341
             self.scanline += 1
 
@@ -50,6 +53,12 @@ class NesPPU {
         return false
     }
 
+    func checkSprite0Hit(_ cycle: Int) -> Bool {
+        let y = Int(oamData[0])
+        let x = Int(oamData[0])
+        return (y == scanline) && x <= cycle && mask.showSprites()
+    }
+
     func pollNMI() -> UInt8? {
         let tmp = self.nmiInterrupt
         self.nmiInterrupt = nil

Sources/PPU/Registers/ControlRegister.swift

@@ -70,4 +70,19 @@ struct ControlRegister: OptionSet {
             1
         }
     }
+
+    func nametableAddr() -> UInt16 {
+        switch rawValue & 0b11 {
+        case 0:
+            0x2000
+        case 1:
+            0x2400
+        case 2:
+            0x2800
+        case 3:
+            0x2c00
+        default:
+            fatalError("naemtableAddr: Not possible!")
+        }
+    }
 }

Sources/Render/Render.swift

@@ -1,36 +1,40 @@
 class Render {
     static func render(_ ppu: NesPPU, frame: Frame) {
-        let bank = ppu.ctrl.backgroundPatternAddr()
+        let scroll = (x: Int(ppu.scroll.x), y: Int(ppu.scroll.y))
 
-        for i in 0..<0x03c0 { // FIXME: For now, just use first nametable
-            let tileAddr = UInt16(ppu.vram[i])
-            let tileLoc = (col: i % 32, row: i / 32)
-            let tile = ppu.chrRom[(bank + Int(tileAddr) * 16)...(bank + Int(tileAddr) * 16 + 15)]
-            let bgPalette = getBgPalette(ppu, tileLoc: tileLoc)
-
-            // MARK: Draw Background
-            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 & lower) << 1 | (1 & upper)
-                    upper = upper >> 1
-                    lower = lower >> 1
-                    let rgb = switch value {
-                        case 0:
-                            NESColor.SYSTEM_PALLETE[Int(ppu.paletteTable[0])]
-                        case 1:
-                            NESColor.SYSTEM_PALLETE[Int(bgPalette[1])]
-                        case 2:
-                            NESColor.SYSTEM_PALLETE[Int(bgPalette[2])]
-                        case 3:
-                            NESColor.SYSTEM_PALLETE[Int(bgPalette[3])]
+        let (mainNametable, secondNametable) = switch (ppu.mirroring, ppu.ctrl.nametableAddr()) {
+        case (.vertical, 0x2000), (.vertical, 0x2800), (.horizontal, 0x2000), (.horizontal, 0x2400):
+            (ppu.vram[0..<0x400], ppu.vram[0x400..<0x800])
+        case (.vertical, 0x2400), (.vertical, 0x2c00), (.horizontal, 0x2800), (.horizontal, 0x2c00):
+            (ppu.vram[0x400..<0x800], ppu.vram[0..<0x400])
         default:
-                            fatalError("Invalid Pallete Color type")
-                    }
-                    frame.setPixel((tileLoc.col * 8 + x, tileLoc.row * 8 + y), rgb)
+            fatalError("cringe looking nametable arrangment: \(ppu.mirroring)")
         }
+
+        renderNameTable(
+            ppu,
+            frame: frame,
+            nameTable: Array(mainNametable),
+            viewPort: Rect(x1: scroll.x, y1: scroll.y, x2: 256, y2: 240),
+            shift: (-scroll.x, -scroll.y)
+        )
+
+        if scroll.x > 0 {
+            renderNameTable(
+                ppu,
+                frame: frame,
+                nameTable: Array(secondNametable),
+                viewPort: Rect(x1: 0, y1: 0, x2: scroll.x, y2: 240),
+                shift: (256 - scroll.x, 0)
+            )
+        } else if scroll.y > 0 {
+            renderNameTable(
+                ppu,
+                frame: frame,
+                nameTable: Array(secondNametable),
+                viewPort: Rect(x1: 0, y1: 0, x2: 256, y2: scroll.y),
+                shift: (0, 240 - scroll.y)
+            )
         }
 
         // MARK: Draw Sprites
@@ -52,7 +56,7 @@ class Render {
                 var upper = tile[tile.startIndex + y]
                 var lower = tile[tile.startIndex + y + 8]
 
-                    for x in (0...7).reversed() {
+                for x in [7,6,5,4,3,2,1,0] {
                     let value = (1 & lower) << 1 | (1 & upper)
                     upper = upper >> 1
                     lower = lower >> 1
@@ -83,11 +87,51 @@ class Render {
             }
         }
     }
+
+    static func renderNameTable(_ ppu: NesPPU, frame: Frame, nameTable: [UInt8], viewPort: Rect, shift: (x: Int, y: Int)) {
+       let bank = ppu.ctrl.backgroundPatternAddr()
+       let attributeTable = nameTable[0x3c0..<0x400]
+
+       for i in 0..<0x3c0 {
+            let tileAddr = UInt16(nameTable[i])
+            let tileLoc = (col: i % 32, row: i / 32)
+            let tile = ppu.chrRom[(bank + Int(tileAddr) * 16)...(bank + Int(tileAddr) * 16 + 15)]
+            let bgPalette = getBgPalette(ppu, tileLoc: tileLoc, attributeTable: Array(attributeTable))
+
+            // MARK: Draw Background
+            for y in 0...7 {
+                var upper = tile[tile.startIndex + y]
+                var lower = tile[tile.startIndex + y + 8]
+
+                for x in [7,6,5,4,3,2,1,0] {
+                    let value = (1 & lower) << 1 | (1 & upper)
+                    upper = upper >> 1
+                    lower = lower >> 1
+                    let rgb = switch value {
+                        case 0:
+                            NESColor.SYSTEM_PALLETE[Int(ppu.paletteTable[0])]
+                        case 1:
+                            NESColor.SYSTEM_PALLETE[Int(bgPalette[1])]
+                        case 2:
+                            NESColor.SYSTEM_PALLETE[Int(bgPalette[2])]
+                        case 3:
+                            NESColor.SYSTEM_PALLETE[Int(bgPalette[3])]
+                        default:
+                            fatalError("Invalid Pallete Color type")
                     }
 
-    static func getBgPalette(_ ppu: NesPPU, tileLoc: (col: Int, row: Int)) -> [UInt8] {
+                    let pixelLoc = (x: tileLoc.col * 8 + x, y: tileLoc.row * 8 + y)
+                    if pixelLoc.x >= viewPort.x1 && pixelLoc.x < viewPort.x2 && pixelLoc.y >= viewPort.y1 && pixelLoc.y < viewPort.y2 {
+                        frame.setPixel((shift.x + pixelLoc.x, shift.y + pixelLoc.y), rgb)
+                    }
+                }
+            }
+       }
+    }
+
+    static func getBgPalette(_ ppu: NesPPU, tileLoc: (col: Int, row: Int), attributeTable: [UInt8]) -> [UInt8] {
         let attrTableIndex = tileLoc.row / 4 * 8 + tileLoc.col / 4
-        let attrByte = ppu.vram[0x3c0 + attrTableIndex] // FIXME: still using hardcoded first nametable
+        let attrByte = attributeTable[attrTableIndex]
 
         let palleteIndex = switch (tileLoc.col % 4 / 2, tileLoc.row % 4 / 2) {
         case (0,0):
@@ -103,7 +147,12 @@ class Render {
         }
 
         let palleteStartIndex = 1 + Int(palleteIndex) * 4
-        return [ppu.paletteTable[0], ppu.paletteTable[palleteStartIndex], ppu.paletteTable[palleteStartIndex + 1], ppu.paletteTable[palleteStartIndex + 2]]
+        return [
+            ppu.paletteTable[0],
+            ppu.paletteTable[palleteStartIndex],
+            ppu.paletteTable[palleteStartIndex + 1],
+            ppu.paletteTable[palleteStartIndex + 2],
+        ]
     }
 
     static func getSpritePalette(_ ppu: NesPPU, paletteIndex: UInt8) -> [UInt8] {
@@ -116,3 +165,10 @@ class Render {
         ]
     }
 }
+
+struct Rect {
+    let x1: Int
+    let y1: Int
+    let x2: Int
+    let y2: Int
+}

Sources/main.swift

@@ -21,88 +21,36 @@ SDL_RenderSetScale(canvas, 3.0, 3.0)
 var texture = SDL_CreateTexture(canvas, SDL_PIXELFORMAT_RGB24.rawValue, Int32(SDL_TEXTUREACCESS_TARGET.rawValue), 256, 240)
 
 var event = SDL_Event()
-var quit = false
 
-// func handleUserInput(_ cpu: CPU, event: inout SDL_Event) {
-//     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)
-//             case SDLK_w:
-//                 cpu.memWrite(0xff, data: 0x77)
-//             case SDLK_a:
-//                 cpu.memWrite(0xff, data: 0x61)
-//             case SDLK_s:
-//                 cpu.memWrite(0xff, data: 0x73)
-//             case SDLK_d:
-//                 cpu.memWrite(0xff, data: 0x64)
-//             default:
-//                 continue
-//             }
-//         }
-//     }
-// }
+guard let bytes = NSData(contentsOfFile: "smb1.nes") else { fatalError("Rom not found") }
 
-// func color(_ byte: UInt8) -> SDL_Color {
-//     switch byte{
-//     case 0:
-//         return SDL_Color(r: 0, g: 0, b: 0, a: 255)
-//     case 1:
-//         return SDL_Color(r: 255, g: 255, b: 255, a: 255)
-//     case 2, 9:
-//         return SDL_Color(r: 128, g: 128, b: 128, a: 255)
-//     case 3, 10:
-//         return SDL_Color(r: 255, g: 0, b: 0, a: 255)
-//     case 4, 11:
-//         return SDL_Color(r: 0, g: 255, b: 0, a: 255)
-//     case 5, 12:
-//         return SDL_Color(r: 0, g: 0, b: 255, a: 255)
-//     case 6, 13:
-//         return SDL_Color(r: 255, g: 0, b: 255, a: 255)
-//     case 7, 14:
-//         return SDL_Color(r: 255, g: 255, b: 0, a: 255)
-//     default:
-//         return SDL_Color(r: 0, g: 255, b: 255, a: 255)
-
-//     }
-// }
-
-// func readScreenState(_ cpu: CPU, frame: inout [UInt8]) -> Bool {
-
-//     var frame_idx = 0
-//     var update = false
-//     for i in 0x0200..<0x600 {
-//         let color_idx = cpu.memRead(UInt16(i))
-//         let color = color(color_idx)
-//         let (b1, b2, b3) = (color.r, color.b, color.g)
-//         if frame[frame_idx] != b1 || frame[frame_idx + 1] != b2 || frame[frame_idx + 2] != b3 {
-//            frame[frame_idx] = b1;
-//            frame[frame_idx + 1] = b2;
-//            frame[frame_idx + 2] = b3;
-//            update = true;
-//        }
-//         frame_idx += 3
-//     }
-//     return update
-// }
-
-guard let bytes = NSData(contentsOfFile: "pacman.nes") else { fatalError("Rom not found") }
 var gameCode = [UInt8](repeating: 0, count: bytes.length)
 bytes.getBytes(&gameCode, length: bytes.length)
 
 let rom = try Rom(gameCode)
+let joypad1 = Joypad()
 
+let keyMap = [
+  SDLK_DOWN : JoypadButton.DOWN,
+  SDLK_UP : JoypadButton.UP,
+  SDLK_LEFT : JoypadButton.LEFT,
+  SDLK_RIGHT : JoypadButton.RIGHT,
+  SDLK_SPACE : JoypadButton.SELECT,
+  SDLK_RETURN : JoypadButton.START,
+  SDLK_a : JoypadButton.BUTTON_A,
+  SDLK_s : JoypadButton.BUTTON_B
+]
+
+var timer = Date.now.addingTimeInterval(0.01666)
 var frame = Frame()
-let bus = Bus(rom) { ppu in
+let bus = Bus(rom: rom, joypad1: joypad1) { ppu in 
     Render.render(ppu, frame: frame)
+    // wait here until 16.66 ms have passed
+    // i would use clock_nanosleep but that isn't available cross platform
+    if timer.timeIntervalSinceNow > 0 {
+        usleep(UInt32(timer.timeIntervalSinceNow * 1000000))
+    }
+    timer.addTimeInterval(0.01666)
     SDL_UpdateTexture(texture, nil, frame.data, 256 * 3)
     SDL_RenderCopy(canvas, texture, nil, nil)
     SDL_RenderPresent(canvas)
@@ -114,75 +62,24 @@ let bus = Bus(rom) { ppu in
              exit(0)
          }
         if event.type == SDL_KEYDOWN.rawValue {
-            switch SDL_KeyCode(UInt32(event.key.keysym.sym)) {
+            let keyCode = SDL_KeyCode(UInt32(event.key.keysym.sym))
+            switch keyCode {
             case SDLK_ESCAPE:
                 SDL_DestroyWindow(window)
                 SDL_Quit()
                 exit(0)
             default:
-                continue
+                guard let key = keyMap[keyCode] else { continue }
+                joypad1.setButton(key, pressed: true)
             }
         }
+        if event.type == SDL_KEYUP.rawValue {
+            guard let key = keyMap[SDL_KeyCode(UInt32(event.key.keysym.sym))] else { continue }
+            joypad1.setButton(key, pressed: false)
+        }
     }
 }
 
 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)
-//cpu.load(gameCode)
-//cpu.reset()
-//cpu.programCounter = 0xC000
-
-// var screenState = [UInt8](repeating: 0, count: 32 * 3 * 32)
-// var rng = SystemRandomNumberGenerator()
-// cpu.run(onCycle: {
-//     //print(dumpCpuState(cpu))
-//     handleUserInput(cpu, event: &event)
-//     cpu.memWrite(0xfe, data: UInt8.random(in: 1...16, using: &rng))
-
-//     if readScreenState(cpu, frame: &screenState) {
-//         SDL_UpdateTexture(texture, nil, screenState, 32 * 3)
-//         SDL_RenderCopy(canvas, texture, nil, nil)
-//         SDL_RenderPresent(canvas)
-//     }
-
-//     usleep(70)
-// }, onComplete: {
-//     SDL_DestroyWindow(window)
-//     SDL_Quit()
-//     exit(0)
-// })
-
-// Infinite loop otherwise the program will exit prematurely
-// RunLoop.main.run()