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PPU: impl scrolling

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This commit is contained in:
Andrew Glaze 2024-08-23 23:36:25 -04:00
parent af3be8d93d
commit 9f12bb2ba0
5 changed files with 119 additions and 35 deletions
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7
Sources/Data/Bus.swift
View File

@ -23,8 +23,11 @@ class Bus {
func tick(_ cycles: UInt8) {
self.cycles += Int(cycles)
let newFrame = self.ppu.tick(cycles * 3)
if newFrame {
let nmiBefore = ppu.nmiInterrupt != nil
_ = self.ppu.tick(cycles * 3)
let nmiAfter = ppu.nmiInterrupt != nil
if !nmiBefore && nmiAfter {
gameloopCallback(ppu)
}

9
Sources/PPU/NesPPU.swift
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@ -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

15
Sources/PPU/Registers/ControlRegister.swift
View File

@ -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!")
}
}
}

120
Sources/Render/Render.swift
View File

@ -1,37 +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)
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("cringe looking nametable arrangment: \(ppu.mirroring)")
}
// MARK: Draw Background
for y in 0...7 {
var upper = tile[tile.startIndex + y]
var lower = tile[tile.startIndex + y + 8]
renderNameTable(
ppu,
frame: frame,
nameTable: Array(mainNametable),
viewPort: Rect(x1: scroll.x, y1: scroll.y, x2: 256, y2: 240),
shift: (-scroll.x, -scroll.y)
)
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")
}
frame.setPixel((tileLoc.col * 8 + x, tileLoc.row * 8 + y), rgb)
}
}
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
@ -85,9 +88,50 @@ class Render {
}
}
static func getBgPalette(_ ppu: NesPPU, tileLoc: (col: Int, row: Int)) -> [UInt8] {
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")
}
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
}

3
Sources/main.swift
View File

@ -22,7 +22,8 @@ var texture = SDL_CreateTexture(canvas, SDL_PIXELFORMAT_RGB24.rawValue, Int32(SD
var event = SDL_Event()
guard let bytes = NSData(contentsOfFile: "pacman.nes") else { fatalError("Rom not found") }
guard let bytes = NSData(contentsOfFile: "smb1.nes") else { fatalError("Rom not found") }
var gameCode = [UInt8](repeating: 0, count: bytes.length)
bytes.getBytes(&gameCode, length: bytes.length)