mirror of
https://github.com/Candygoblen123/SwiftNES.git
synced 2024-09-19 17:01:01 -05:00
108 lines
2.8 KiB
Swift
108 lines
2.8 KiB
Swift
class NesPPU {
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public var paletteTable = [UInt8](repeating: 0, count: 32)
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public var vram = [UInt8](repeating: 0, count: 2048)
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public let mirroring: Mirroring
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public var chrRom: [UInt8]
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private let addr: AddrRegister = AddrRegister()
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private var readBuff: UInt8 = 0
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var ctrl = ControlRegister()
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let status = StatusRegister()
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let scroll = ScrollRegister()
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let mask = MaskRegister()
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var oamAddr: UInt8 = 0
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var oamData = [UInt8](repeating: 0, count: 64 * 4)
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init(_ chrRom: [UInt8], _ mirroring: Mirroring) {
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self.chrRom = chrRom
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self.mirroring = mirroring
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}
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func writeToPPUAddr(_ value: UInt8) {
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addr.update(value)
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}
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func writeToCtrl(_ value: UInt8) {
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ctrl.rawValue = value
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}
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func incrememtVramAddr() {
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addr.increment(ctrl.vramAddrIncrement())
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}
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func readData() -> UInt8 {
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let addr = addr.get()
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incrememtVramAddr()
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switch addr {
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case 0...0x1fff:
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let res = readBuff
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readBuff = chrRom[Int(addr)]
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return res
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case 0x2000...0x2fff:
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let res = readBuff
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readBuff = vram[Int(mirrorVramAddr(addr))]
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return res
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case 0x3000...0x3eff:
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fatalError("addr space 0x3000..0x3eff is not expected to be used, requested = \(addr)")
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case 0x3f00...0x3fff:
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return self.paletteTable[Int(addr - 0x3f00)]
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default:
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fatalError("Unexpected access to mirrored space \(addr)")
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}
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}
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func mirrorVramAddr(_ addr: UInt16) -> UInt16 {
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let mirroredVram = addr & 0b10111111111111 // mirror down 0x3000-0x3eff to 0x2000 - 0x2eff
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let vramIndex = mirroredVram - 0x2000 // to vram array index
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let nameTable = vramIndex / 0x400 // to the name index table
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return switch (mirroring, nameTable) {
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case (.vertical, 2), (.vertical, 3):
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vramIndex - 0x800
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case (.horizontal, 2):
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vramIndex - 0x400
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case (.horizontal, 1):
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vramIndex - 0x400
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case (.horizontal, 3):
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vramIndex - 0x800
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default:
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vramIndex
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}
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}
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func writeToData(_ data: UInt8) {
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fatalError("Not Implemented")
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}
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func readStatus() -> UInt8 {
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let data = status.snapshot()
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status.resetVblankStatus()
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addr.resetLatch()
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scroll.resetLatch()
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return data
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}
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func writeToScroll(_ value: UInt8) {
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scroll.write(value)
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}
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func writeToOamAddr(_ value: UInt8) {
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oamAddr = value
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}
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func writeToOamData(_ value: UInt8) {
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oamData[Int(oamAddr)] = value
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oamAddr = oamAddr &+ 1
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}
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func readOamData() -> UInt8 {
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oamData[Int(oamAddr)]
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}
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func writeToMask(_ value: UInt8) {
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mask.update(value)
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}
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}
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