very basic libretro core (no sound + limited controls)

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "libretro/libretro-common"]
-	path = libretro/libretro-common
-	url = https://github.com/libretro/libretro-common.git

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+  "files.associations": {
+    "libretro.h": "c"
+  }
+}

Makefile

@@ -1,5 +1,5 @@
 TARGET=chip8_libretro
-LIBRETRO_CORE=$(TARGET).so
+LIBRETRO_CORE=$(TARGET).dylib
 LIBRETRO_HEADER=$(TARGET).h
 BUILD_VERSION=$(shell git rev-parse --short HEAD)
 

chip8/chip8.go

@@ -23,6 +23,7 @@ const (
 	Width          = 64
 	Height         = 32
 	FPS            = 60
+	CyclesPerFrame = 8
 	SampleRate     = 44100
 )
 
@@ -98,6 +99,13 @@ func (emulator *Emulator) LoadFont() {
 	})
 }
 
+func (emulator *Emulator) Update() {
+	emulator.UpdateTimers()
+	for cycle := 0; cycle < CyclesPerFrame; cycle++ {
+		emulator.Cycle()
+	}
+}
+
 func (emulator *Emulator) UpdateTimers() {
 	if emulator.ST != 0 {
 		emulator.PlaySound()
@@ -110,6 +118,9 @@ func (emulator *Emulator) UpdateTimers() {
 
 func (emulator *Emulator) Cycle() {
 	instruction := binary.BigEndian.Uint16(emulator.Memory[emulator.PC:])
+	if instruction == 0x0000 {
+		return
+	}
 	emulator.PC += InstructionSize
 
 	nnn := instruction & 0x0FFF

go.mod

@@ -4,6 +4,7 @@ go 1.17
 
 require (
 	github.com/hajimehoshi/ebiten/v2 v2.2.5
+	github.com/lanzafame/bobblehat v0.0.0-20190628174408-a0f0792c1691
 	github.com/stretchr/testify v1.7.0
 )
 

go.sum

@@ -20,6 +20,8 @@ github.com/jfreymuth/vorbis v1.0.2/go.mod h1:DoftRo4AznKnShRl1GxiTFCseHr4zR9BN3T
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/lanzafame/bobblehat v0.0.0-20190628174408-a0f0792c1691 h1:o3aMwSNYkdM+w3zODsAQTGsP09c4r9E2DW42NjYRS0M=
+github.com/lanzafame/bobblehat v0.0.0-20190628174408-a0f0792c1691/go.mod h1:CuWZprWAvuwcm4Sl0Vt1qL8foyta9HIBRLC5qyYtUW4=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/pkg/browser v0.0.0-20180916011732-0a3d74bf9ce4/go.mod h1:4OwLy04Bl9Ef3GJJCoec+30X3LQs/0/m4HFRt/2LUSA=

libretro/bridge.c

@@ -1,55 +0,0 @@
-#include "libretro-common/include/libretro.h"
-#include <string.h>
-
-// RETRO_API void retro_set_environment(retro_environment_t);
-// RETRO_API void retro_set_video_refresh(retro_video_refresh_t);
-// RETRO_API void retro_set_audio_sample(retro_audio_sample_t);
-// RETRO_API void retro_set_audio_sample_batch(retro_audio_sample_batch_t);
-// RETRO_API void retro_set_input_poll(retro_input_poll_t);
-// RETRO_API void retro_set_input_state(retro_input_state_t);
-
-RETRO_API void retro_init(void)
-{
-    void Initialize(void);
-    Initialize();
-}
-
-RETRO_API void retro_deinit(void)
-{
-    void Deinitialize(void);
-    Deinitialize();
-}
-
-RETRO_API unsigned retro_api_version(void)
-{
-    return 1;
-}
-
-RETRO_API void retro_get_system_info(struct retro_system_info *info)
-{
-    memset(info, 0, sizeof(*info));
-    void GetEmulatorInfo(struct retro_system_info * info);
-    GetEmulatorInfo(info);
-}
-
-RETRO_API void retro_get_system_av_info(struct retro_system_av_info *info)
-{
-    memset(info, 0, sizeof(*info));
-    void GetEmulatorAVInfo(struct retro_system_av_info * info);
-    GetEmulatorAVInfo(info);
-}
-
-// RETRO_API void retro_set_controller_port_device(unsigned port, unsigned device);
-// RETRO_API void retro_reset(void);
-// RETRO_API void retro_run(void);
-// RETRO_API size_t retro_serialize_size(void);
-// RETRO_API bool retro_serialize(void *data, size_t size);
-// RETRO_API bool retro_unserialize(const void *data, size_t size);
-// RETRO_API void retro_cheat_reset(void);
-// RETRO_API void retro_cheat_set(unsigned index, bool enabled, const char *code);
-// RETRO_API bool retro_load_game(const struct retro_game_info *game);
-// RETRO_API bool retro_load_game_special(unsigned game_type, const struct retro_game_info *info, size_t num_info);
-// RETRO_API void retro_unload_game(void);
-// RETRO_API unsigned retro_get_region(void);
-// RETRO_API void *retro_get_memory_data(unsigned id);
-// RETRO_API size_t retro_get_memory_size(unsigned id);

libretro/libretro-common

@@ -1 +0,0 @@
-Subproject commit 716bb5e7b761a3b4d44e069c84491d906d32aba0

libretro/libretro.c

@@ -0,0 +1,162 @@
+#include "libretro.h"
+#include <string.h>
+#include <stdio.h>
+
+// callbacks
+static retro_video_refresh_t retro_video_refresh = NULL;
+static retro_input_poll_t retro_input_poll = NULL;
+static retro_input_state_t retro_input_state = NULL;
+
+// input params
+static unsigned input_port = 0;
+static unsigned input_device = 0;
+
+RETRO_API void retro_set_environment(retro_environment_t cb)
+{
+    // TODO: implement this
+}
+
+RETRO_API void retro_set_video_refresh(retro_video_refresh_t cb)
+{
+    retro_video_refresh = cb;
+}
+
+RETRO_API void retro_set_audio_sample(retro_audio_sample_t cb)
+{
+    // TODO: implement this
+}
+
+RETRO_API void retro_set_audio_sample_batch(retro_audio_sample_batch_t cb)
+{
+    // TODO: implement this
+}
+
+RETRO_API void retro_set_input_poll(retro_input_poll_t cb)
+{
+    retro_input_poll = cb;
+}
+
+RETRO_API void retro_set_input_state(retro_input_state_t cb)
+{
+    retro_input_state = cb;
+}
+
+RETRO_API void retro_init(void)
+{
+    void Initialize(void);
+    Initialize();
+}
+
+RETRO_API void retro_deinit(void)
+{
+    void Deinitialize(void);
+    Deinitialize();
+}
+
+RETRO_API unsigned retro_api_version(void)
+{
+    return RETRO_API_VERSION;
+}
+
+RETRO_API void retro_get_system_info(struct retro_system_info *info)
+{
+    memset(info, 0, sizeof(struct retro_system_info));
+    void GetEmulatorInfo(struct retro_system_info * info);
+    GetEmulatorInfo(info);
+}
+
+RETRO_API void retro_get_system_av_info(struct retro_system_av_info *info)
+{
+    memset(info, 0, sizeof(struct retro_system_av_info));
+    void GetEmulatorAVInfo(struct retro_system_av_info * info);
+    GetEmulatorAVInfo(info);
+}
+
+RETRO_API void retro_set_controller_port_device(unsigned port, unsigned device)
+{
+    input_port = port;
+    input_device = device;
+}
+
+RETRO_API void retro_reset(void)
+{
+    void Reset(void);
+    Reset();
+}
+
+RETRO_API void retro_run(void)
+{
+    void Run(void);
+    Run();
+}
+
+RETRO_API size_t retro_serialize_size(void)
+{
+    return 0; // TODO: implement this
+}
+
+RETRO_API bool retro_serialize(void *data, size_t size)
+{
+    return true; // TODO: implement this
+}
+
+RETRO_API bool retro_unserialize(const void *data, size_t size)
+{
+    return true; // TODO: implement this
+}
+
+RETRO_API void retro_cheat_reset(void)
+{
+    // TODO: implement this
+}
+
+RETRO_API void retro_cheat_set(unsigned index, bool enabled, const char *code)
+{
+    // TODO: implement this
+}
+
+RETRO_API bool retro_load_game(const struct retro_game_info *game)
+{
+    bool LoadGame(struct retro_game_info *);
+    return LoadGame((struct retro_game_info *)game);
+}
+
+RETRO_API bool retro_load_game_special(unsigned game_type, const struct retro_game_info *info, size_t num_info)
+{
+    return true; // TODO: implement this
+}
+
+RETRO_API void retro_unload_game(void)
+{
+    // TODO: implement this
+}
+
+RETRO_API unsigned retro_get_region(void)
+{
+    return RETRO_REGION_NTSC;
+}
+
+RETRO_API void *retro_get_memory_data(unsigned id)
+{
+    return NULL; // TODO: implement this
+}
+
+RETRO_API size_t retro_get_memory_size(unsigned id)
+{
+    return 0; // TODO: implement this
+}
+
+void VideoRefresh(const void *data, unsigned width, unsigned height, size_t pitch)
+{
+    retro_video_refresh(data, width, height, pitch);
+}
+
+void InputPoll(void)
+{
+    retro_input_poll();
+}
+
+int16_t InputState(unsigned id)
+{
+    return retro_input_state(0, RETRO_DEVICE_JOYPAD, 0, id);
+}

libretro/libretro.go

@@ -1,27 +1,70 @@
 package main
 
 /*
-#include "libretro-common/include/libretro.h"
+#include "libretro.h"
 
 typedef struct retro_system_info retro_system_info;
 typedef struct retro_system_av_info retro_system_av_info;
+typedef struct retro_game_info retro_game_info;
+
+void VideoRefresh(const void *data, unsigned width, unsigned height, size_t pitch);
+void InputPoll(void);
+int16_t InputState(unsigned id);
 */
 import "C"
 import (
+	"image"
+	"image/draw"
+	"io/ioutil"
+	"log"
+	"unsafe"
+
+	"github.com/lanzafame/bobblehat/sense/screen/color"
 	"github.com/tangzero/chip8-emulator/chip8"
 )
 
+const (
+	RetroButtonB uint8 = iota
+	RetroButtonY
+	RetroButtonSelect
+	RetroButtonStart
+	RetroButtonUp
+	RetroButtonDown
+	RetroButtonLeft
+	RetroButtonRight
+	RetroButtonA
+	RetroButtonX
+	RetroButtonL
+	RetroButtonR
+	FirstRetroButton = RetroButtonB
+	LastRetroButton  = RetroButtonR
+)
+
+var KeyMapping = map[uint8]uint8{
+	RetroButtonLeft:  0x04,
+	RetroButtonX:     0x05,
+	RetroButtonRight: 0x06,
+}
+
 var BuildVersion string
-var emulator *chip8.Emulator
+var Emulator *chip8.Emulator
+var FrameBuffer *color.RGB565
+var KeysState [16]bool
 
 //export Initialize
 func Initialize() {
-	emulator = chip8.NewEmulator(nil, nil)
+	playSound := func() {}
+	stopSound := func() {}
+	soundPlayer := func([]byte) (func(), func()) { return playSound, stopSound }
+
+	Emulator = chip8.NewEmulator(KeyPressed, soundPlayer)
+
+	FrameBuffer = color.NewRGB565(Emulator.Display.Rect)
 }
 
 //export Deinitialize
 func Deinitialize() {
-	emulator = nil
+	Emulator = nil
 }
 
 //export GetEmulatorInfo
@@ -29,7 +72,7 @@ func GetEmulatorInfo(info *C.retro_system_info) {
 	info.library_name = C.CString("CHIP-8 Emulator by TangZero")
 	info.library_version = C.CString(BuildVersion)
 	info.valid_extensions = C.CString("ch8")
-	info.need_fullpath = false
+	info.need_fullpath = true
 	info.block_extract = false
 }
 
@@ -44,4 +87,47 @@ func GetEmulatorAVInfo(info *C.retro_system_av_info) {
 	info.timing.sample_rate = 44100
 }
 
+//export Reset
+func Reset() {
+	Emulator.Reset()
+}
+
+//export Run
+func Run() {
+	C.InputPoll()
+	UpdateKeysState()
+
+	Emulator.Update()
+
+	// convert from RGBA to RGB565
+	draw.Draw(FrameBuffer, Emulator.Display.Rect, Emulator.Display, image.Point{}, draw.Src)
+
+	// draw frame
+	C.VideoRefresh(unsafe.Pointer(&FrameBuffer.Pix[0]), chip8.Width, chip8.Height, C.size_t(FrameBuffer.Stride))
+}
+
+//export LoadGame
+func LoadGame(game *C.retro_game_info) bool {
+	data, err := ioutil.ReadFile(C.GoString(game.path))
+	if err != nil {
+		log.Println(err)
+		return false
+	}
+	Emulator.LoadROM(chip8.ROM{Data: data})
+	return true
+}
+
+func UpdateKeysState() {
+	for button := FirstRetroButton; button < LastRetroButton; button++ {
+		key, ok := KeyMapping[button]
+		if ok {
+			KeysState[key] = C.InputState(C.uint(button)) > 0
+		}
+	}
+}
+
+func KeyPressed(key uint8) bool {
+	return KeysState[key]
+}
+
 func main() {}

main.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	_ "embed"
 	"log"
-	"time"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/audio"
@@ -57,24 +56,11 @@ type GUI struct {
 	Emulator *chip8.Emulator
 }
 
-func (gui *GUI) Run() {
-	for {
-		gui.Emulator.Cycle()
-		time.Sleep(time.Millisecond * 2)
-	}
-}
-
 func (gui *GUI) Update() error {
 	if ebiten.IsKeyPressed(ebiten.KeyEscape) {
 		gui.Emulator.Reset()
 	}
-	switch gui.State {
+	gui.Emulator.Update()
-	case LoadingState:
-		go gui.Run()
-		gui.State = RunningState
-	case RunningState:
-		gui.Emulator.UpdateTimers()
-	}
 	return nil
 }