PPU: work on rendering

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)
+                }
+            }
+        }
+    }
+}