move main.go to root so go build actually builds

1 files changed, 153 insertions, 0 deletions

diff --git a/main.go b/main.go
new file mode 100644
index 0000000..2ce3745
--- /dev/null
+++ b/main.go
@@ -0,0 +1,153 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+	"runtime"
+	"time"
+
+	"github.com/veandco/go-sdl2/sdl"
+
+	"crecher.net/gones/v2/cart"
+	"crecher.net/gones/v2/nes"
+	"crecher.net/gones/v2/ppu"
+)
+
+const (
+	windowScale = 3
+
+	// nes: 1789773 cpu cycles per sec / 29780.5 cycles per frame
+	framesPerSecond = 60.0988
+)
+
+func init() {
+	// sdl wants to be driven from the main thread
+	runtime.LockOSThread()
+}
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "usage: %s <rom.nes>\n", os.Args[0])
+		os.Exit(2)
+	}
+	if err := run(os.Args[1]); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run(romPath string) error {
+	c, err := cart.Load(romPath)
+	if err != nil {
+		return err
+	}
+	console := nes.New(c)
+	name := filepath.Base(romPath)
+
+	if err := sdl.Init(sdl.INIT_VIDEO); err != nil {
+		return err
+	}
+	defer sdl.Quit()
+
+	window, err := sdl.CreateWindow("gones - "+name,
+		sdl.WINDOWPOS_CENTERED, sdl.WINDOWPOS_CENTERED,
+		ppu.ScreenWidth*windowScale, ppu.ScreenHeight*windowScale,
+		sdl.WINDOW_SHOWN|sdl.WINDOW_RESIZABLE)
+	if err != nil {
+		return err
+	}
+	defer window.Destroy()
+
+	renderer, err := sdl.CreateRenderer(window, -1, sdl.RENDERER_ACCELERATED|sdl.RENDERER_PRESENTVSYNC)
+	if err != nil {
+		return err
+	}
+	defer renderer.Destroy()
+
+	// the window can be resized freely, sdl scales (and letterboxes) the 256x240 picture
+	if err := renderer.SetLogicalSize(ppu.ScreenWidth, ppu.ScreenHeight); err != nil {
+		return err
+	}
+
+	// framebuffer is ARGB8888, streaming since we rewrite it every frame
+	texture, err := renderer.CreateTexture(sdl.PIXELFORMAT_ARGB8888, sdl.TEXTUREACCESS_STREAMING,
+		ppu.ScreenWidth, ppu.ScreenHeight)
+	if err != nil {
+		return err
+	}
+	defer texture.Destroy()
+
+	fps := framesPerSecond // a variable, a constant would have to be a whole number of nanoseconds
+	frameTime := time.Duration(float64(time.Second) / fps)
+	next := time.Now()
+	fpsStart, frames := next, 0
+	jamShown := false
+
+	for {
+		for e := sdl.PollEvent(); e != nil; e = sdl.PollEvent() {
+			switch ev := e.(type) {
+			case *sdl.QuitEvent:
+				return nil
+			case *sdl.KeyboardEvent:
+				if ev.Type == sdl.KEYDOWN && ev.Keysym.Sym == sdl.K_ESCAPE {
+					return nil
+				}
+			}
+		}
+
+		console.SetButtons(0, heldButtons())
+		console.StepFrame()
+
+		// UpdateRGBA multiplies the pitch by 4 itself, so this is in pixels, not bytes
+		if err := texture.UpdateRGBA(nil, console.PPU.Framebuffer(), ppu.ScreenWidth); err != nil {
+			return err
+		}
+		renderer.Clear()
+		renderer.Copy(texture, nil, nil)
+		renderer.Present()
+
+		if console.CPU.Jammed && !jamShown {
+			window.SetTitle("gones - " + name + " - CPU jammed (reset needed)")
+			jamShown = true
+		}
+
+		frames++
+		if elapsed := time.Since(fpsStart); elapsed >= time.Second && !jamShown {
+			window.SetTitle(fmt.Sprintf("gones - %s - %.1f fps", name, float64(frames)/elapsed.Seconds()))
+			fpsStart, frames = time.Now(), 0
+		}
+
+		// vsync alone would run too fast on a 120/144hz monitor, so pace to the nes frame rate
+		next = next.Add(frameTime)
+		if wait := time.Until(next); wait > 0 {
+			time.Sleep(wait)
+		} else if wait < -100*time.Millisecond {
+			next = time.Now() // fell far behind (window drag etc), don't try to catch up
+		}
+	}
+}
+
+// keyboard layout for controller 1
+// TODO: add remapping
+var keyMap = map[sdl.Scancode]uint8{
+	sdl.SCANCODE_X:      nes.ButtonA,
+	sdl.SCANCODE_Y:      nes.ButtonB,
+	sdl.SCANCODE_RSHIFT: nes.ButtonSelect,
+	sdl.SCANCODE_RETURN: nes.ButtonStart,
+	sdl.SCANCODE_UP:     nes.ButtonUp,
+	sdl.SCANCODE_DOWN:   nes.ButtonDown,
+	sdl.SCANCODE_LEFT:   nes.ButtonLeft,
+	sdl.SCANCODE_RIGHT:  nes.ButtonRight,
+}
+
+func heldButtons() uint8 {
+	keys := sdl.GetKeyboardState()
+	var b uint8
+	for scancode, button := range keyMap {
+		if keys[scancode] != 0 {
+			b |= button
+		}
+	}
+	return b
+}