Fun with Native Code

Presented at Droidcon San Francisco, November 2017

Transcript

1. Eric Butler @codebutler Droidcon San Francisco November 2017 FUN WITH NATIVE CODE
2. How This All Started
3. Problems with Existing Apps Complicated Setup Broken Controller Support Touchscreen Required Ugly UI Intrusive Ads Bad Performance etc…
4. Designing My Dream App Androidy TV Interface Works with game controllers Loads games from cloud Supports all retro consoles
 Leanback Support Library Android Input APIs Google Drive/Dropbox SDKs ??
5. open source retro video game emulator library Google Search I’m Feeling Unlucky
7. • Single API that abstracts many retro console emulators. • Specifically designed to make writing frontends easy. • Free, open-source. • Well documented API. • Lightweight cross-platform C library. • Perfect?
8. • Single API that abstracts many retro console emulators • Specifically designed to make writing frontends easy. • Free, open-source. • Well documented API. • Lightweight cross-platform C library. • Perfect? h no…
9. Foreign Function Interface ? FFI High-level language Low-level language
10. Foreign Function Interface Python CTypes C# P/Invoke Java Native Interface
11. JVM CODE
12. JVM CODE NATIVE CODE Image: http://www.cakesandcomics.com/#/stranger-things/
14. $ cat test.c #include <stdio.h> void say_hello(const char* name) { printf("Hello %s!\n", name); } 
 $ clang -shared -o libtest.dylib test.c A simple C shared library
15. void say_hello(const char* name); $ cat test.py from ctypes import * lib = cdll.LoadLibrary("libtest.dylib") lib.say_hello("Droidcon") $ python test.py Hello Droidcon! Calling our native function with Python CTypes
16. void say_hello(const char* name); Calling our native function with C# PInvoke $ cat Test.cs using System.Runtime.InteropServices; static class LibTest { [DllImport("libtest.dylib")] public static extern void say_hello(string name); } LibTest.say_hello("Droidcon") $ csharp Test.cs Hello Droidcon!
17. void say_hello(const char* name); Calling our native function with Kotlin JNI…? $ cat test.kts
 external fun say_hello(name: String) System.loadLibrary("test") say_hello("Droidcon") $ kotlin -script test.kts java.lang.UnsatisfiedLinkError: Test.say_hello(Ljava/lang/String;)V at Test.say_hello(Native Method) at Test.<init>(Unknown Source)
18. void say_hello(const char* name);
19. A simple C shared library $ cat test.c Z1Z1Z1Z1 
 $ clang -shared -o libtest.dylib test.c Z5Z5Z5Z5 #include <stdio.h>Z2Z2Z2Z2 void say_hello(const char* name) {Z3Z3Z3Z3 printf("Hello %s!\n", name); }Z4Z4Z4Z4
20. $ cat test.cpp Z1Z1Z1Z1
 #include <stdio.h>Z2Z2Z2Z2 #include <jni.h> extern "C" { void say_hello(const char* name) {Z3Z3Z3Z3 printf("Hello %s!\n", name); }Z4Z4Z4Z4 JNIEXPORT void JNICALL Java_Test_sayHello( JNIEnv *env, jclass cls, jstring name) { const char *nativeHello = env->GetStringUTFChars(name, JNI_FALSE); say_hello(nativeHello); env->ReleaseStringUTFChars(name, nativeHello); } } $ clang++ -shared -o libtest.dylib \ -I${JAVA_HOME}/include -I${JAVA_HOME}/include/darwin test.cpp Z5Z5Z5Z5 A (not so) simple JNI-compatible C++ shared library
21. JNIEXPORT void JNICALL Java_Test_sayHello( JNIEnv *env, jclass cls, jstring name); Calling our native function with Kotlin JNI $ cat test.kts
 external fun sayHello(name: String) System.loadLibrary("test") sayHello("Droidcon") $ kotlin -script test.kts Hello Droidcon!
23. call native code from java without jni Google Search I’m Feeling Hopeless
24. JNA: Java Native Access
25. “JNA provides Java programs easy access to native shared libraries without writing anything but Java code - no JNI or native code is required.
 This functionality is comparable to C#’s PInvoke and Python's ctypes.” github.com/java-native-access/jna JNA: Java Native Access Kotlin Kotlin
26. JNA Features Functions Methods C JVM Data Types Primitives Structs Classes Function Pointers Callback Interfaces
27. package com.sun.jna Library Native Structure Callback Pointer
28. Base type for interfaces containing native library function definitions. interface Library interface TestLibrary : Library { fun some_method() }
29. Static methods for loading native libraries, JNA configuration, and other utility tasks. final class Native val lib = Native.loadLibrary( "libName", TestLibrary::class.java) lib.some_method()
30. Base type for classes that are automatically mapped to/from native structs. abstract class Structure class example_struct : Structure() { } @JvmField var field1: String? = null @JvmField var field2: String? = null override fun getFieldOrder() = listOf("field1", “field2")
31. Base type for callback interfaces to be used as function pointers. Requires one public method. interface Callback interface my_callback : Callback { fun invoke() } interface TestLibrary : Library { fun set_callback(cb: my_callback) } val lib = Native.loadLibrary(/* … */) lib.set_callback(object : my_callback { override fun invoke() { /* TODO */ } })
32. Represents a native pointer, used for accessing arbitrary memory. class Pointer interface TestLibrary : Library { fun set_memory(pointer: Pointer) fun get_memory(): Pointer } interface my_callback : Callback { fun invoke(data: Pointer) }
33. Represents a native pointer, used for accessing arbitrary memory. class Pointer Pointer#getString(offset) Pointer#getInt(offset) Pointer#getLong(offset) Pointer#getByteArray(offset, length) Pointer#read(offset, buffer, index, length) // etc…
34. JNA Performance https://github.com/java-native-access/jna/blob/master/www/FrequentlyAskedQuestions.md • Call overhead up to 10x slower
35. JNA Performance https://github.com/java-native-access/jna/blob/master/www/FrequentlyAskedQuestions.md • Call overhead up to 10x slower • Ease of programing outweighs difference • Build, measure, optimize • Incrementally rewrite using JNI if needed
36. $ cat test.c #include <stdio.h> void say_hello(const char* name) { printf("Hello %s!\n", name); } 
 $ clang -shared -o libtest.dylib test.c A simple C shared library, one last time
37. void say_hello(const char* name) Calling our function from Kotlin with JNA!
38. Calling our function from Kotlin with JNI…? external fun say_hello(name: String) System.loadLibrary("test") say_hello("Droidcon") void say_hello(const char* name)
39. Calling our function from Kotlin with JNA! import com.sun.jna.* 
 external fun say_hello(name: String) System.loadLibrary("test") say_hello("Droidcon") void say_hello(const char* name)
40. Calling our function from Kotlin with JNA! import com.sun.jna.* external fun say_hello(name: String) System.loadLibrary("test") say_hello("Droidcon") void say_hello(const char* name) interface TestLib: Library { }
41. Calling our function from Kotlin with JNA! import com.sun.jna.* fun say_hello(name: String) System.loadLibrary("test") say_hello("Droidcon") void say_hello(const char* name) interface TestLib: Library { }
42. Calling our function from Kotlin with JNA! import com.sun.jna.* fun say_hello(name: String) val lib = Native.loadLibrary("test", TestLib::class.java)ZZZ say_hello("Droidcon") void say_hello(const char* name) interface TestLib: Library { }
43. Calling our function from Kotlin with JNA! import com.sun.jna.* fun say_hello(name: String) val lib = Native.loadLibrary("test", TestLib::class.java)ZZZ lib.say_hello("Droidcon") void say_hello(const char* name) interface TestLib: Library { }
44. void say_hello(const char* name) Calling our function from Kotlin with JNA! $ cat test-jna.kts 
 import com.sun.jna.* interface TestLib: Library { fun say_hello(name: String) } val lib = Native.loadLibrary("test", TestLib::class.java) lib.say_hello("Droidcon") $ mvn dependency:get \ -Dartifact=net.java.dev.jna:jna:4.5.0 \ -Ddest=jna.jar $ kotlinc -cp jna.jar -script test-jna.kts Hello Droidcon!
45. My Dream App Androidy TV Interface Works with game controllers Loads games from cloud Supports all retro consoles
 Leanback Support Library Android Input APIs Google Drive/Dropbox SDKs ??
46. My Dream App Androidy TV Interface Works with game controllers Loads games from cloud Supports all retro consoles
 Leanback Support Library Android Input APIs Google Drive/Dropbox SDKs libretro + JNA
47. Learning Libretro Documentation C Headers Core Implementations Existing Frontends
48. Libretro Documentation bit.ly/libretro-pdf doc.libretro.com/specs/api
49. libretro.h • Single header file • 2178 lines • Mostly documentation comments! • 25 functions, 31 structs
50. Libretro Cores • “core”: An emulator that has been ported to the common libretro API. • Useful to see which APIs are actually needed. • https://github.com/libretro/snes9x/blob/master/libretro/libretro.cpp • https://github.com/libretro/Genesis-Plus-GX/blob/master/libretro/libretro.c
51. Libretro: Existing Frontends RetroArch C++ retroarch.com Phoenix Qt/C++ phoenix.vg GNOME Games C/Vala wiki.gnome.org/ Apps/Games
52. Libretro Architecture Init Callbacks Load Game ROM Run Game Loop Waveform https://thenounproject.com/icon/1345324/
 NES Cartridge https://thenounproject.com/icon/1127992/
 Refresh https://thenounproject.com/icon/974170/
53. Libretro Architecture: Callbacks Video Callback: Called once per frame with a pointer to video data. Input Callback: Called for every supported button on every frame. Return true if button is pressed. Audio Callback: Called once per frame with a pointer to audio data. “Environment” Callback: Generic callback for obscure functions. Mostly unused, per documentation.
54. Libretro Architecture: Loading Games Two Options 1. Core loads game, specify file path. 2. Frontend loads game, specify memory pointer.
55. Libretro Architecture: Game Loop Libretro runs one frame at a time. Frontend maintains the framerate.
56. libretro + JNA 1. Write library bindings. 2. Implement callbacks. 3. Call functions.
57. JNAerator github.com/nativelibs4java/JNAerator
58. build.gradle dependencies { implementation 'net.java.dev.jna:jna:4.5.0@aar' }
59. Native Libraries Go Here
60. Writing Bindings: Initialize void retro_init(void);
61. Writing Bindings: Initialize void retro_init(void); interface LibRetro : Library { fun retro_init() } LibRetro.kt libretro.h
62. Writing Bindings: Load Game bool retro_load_game(retro_game_info);
63. Writing Bindings: Load Game struct retro_game_info {AA const char *path; const void *data; size_t size; const char *meta; }; bool retro_load_game(retro_game_info);
64. Writing Bindings: Load Game struct retro_game_info {AA const char *path; const void *data; size_t size; const char *meta; }; bool retro_load_game(retro_game_info); LibRetro.kt libretro.h
65. Writing Bindings: Load Game struct retro_game_info { const char *path; const void *data; size_t size; const char *meta; }; bool retro_load_game(retro_game_info); class retro_game_info : Structure() { }AA struct retro_game_info 
 }; LibRetro.kt libretro.h
66. Writing Bindings: Load Game struct retro_game_info { const char *path; const void *data; size_t size; const char *meta; }; bool retro_load_game(retro_game_info); class retro_game_info : Structure() { }AA const char *path; const void *data; size_t size; const char *meta; @JvmField var path: String? = null @JvmField var data: Pointer? = null @JvmField var size: SizeT = SizeT() @JvmField var meta: String? = null LibRetro.kt libretro.h
67. Writing Bindings: Load Game struct retro_game_info { const char *path; const void *data; size_t size; const char *meta; }; bool retro_load_game(retro_game_info); class retro_game_info : Structure() { @JvmField var path: String? = null @JvmField var data: Pointer? = null @JvmField var size: SizeT = SizeT() @JvmField var meta: String? = null }AAA override fun getFieldOrder() = listOf("path", "data", "size", "meta") LibRetro.kt libretro.h
68. Writing Bindings: Load Game struct retro_game_info { const char *path; const void *data; size_t size; const char *meta; }; bool retro_load_game(retro_game_info); class retro_game_info : Structure() { @JvmField var path: String? = null @JvmField var data: Pointer? = null @JvmField var size: SizeT = SizeT() @JvmField var meta: String? = null override fun getFieldOrder() = listOf("path", "data", "size", "meta") }AAA bool retro_load_game(retro_game_info); interface LibRetro : Library { fun retro_load_game(info: retro_game_info): Boolean } LibRetro.kt libretro.h
69. Writing Bindings: Audio Callback void retro_set_audio_sample_batch(retro_audio_sample_batch_t);
70. Writing Bindings: Audio Callback typedef size_t (*retro_audio_sample_batch_t)( const int16_t *data, size_t frames); void retro_set_audio_sample_batch(retro_audio_sample_batch_t);
71. Writing Bindings: Audio Callback void retro_set_audio_sample_batch(retro_audio_sample_batch_t); interface retro_audio_sample_batch : Callback { fun invoke(data: Pointer, frames: SizeT): SizeT }AA typedef size_t (*retro_audio_sample_batch_t)( const int16_t *data, size_t frames); LibRetro.kt libretro.h
72. Writing Bindings: Audio Callback void retro_set_audio_sample_batch(retro_audio_sample_batch_t); typedef size_t (*retro_audio_sample_batch_t)( const int16_t *data, size_t frames); interface retro_audio_sample_batch : Callback { fun invoke(data: Pointer, frames: SizeT): SizeT }AA interface LibRetro : Library { fun retro_set_audio_sample_batch(cb: retro_audio_sample_batch) } LibRetro.kt libretro.h
73. Writing Bindings: Video Callback void retro_set_video_refresh(retro_video_refresh_t);
74. Writing Bindings: Video Callback typedef void (*retro_video_refresh_t) ( const void *data, unsigned width, unsigned height, size_t pitch); void retro_set_video_refresh(retro_video_refresh_t);
75. Writing Bindings: Video Callback void retro_set_video_refresh(retro_video_refresh_t); interface retro_video_refresh : Callback { fun invoke( data: Pointer, width: UnsignedInt, height: UnsignedInt,
 pitch: SizeT) } typedef void (*retro_video_refresh_t) ( const void *data, unsigned width, unsigned height, size_t pitch); LibRetro.kt libretro.h
76. Writing Bindings: Video Callback interface retro_video_refresh : Callback { fun invoke( data: Pointer, width: UnsignedInt, height: UnsignedInt,
 pitch: SizeT) } void retro_set_video_refresh(retro_video_refresh_t); typedef void (*retro_video_refresh_t) ( const void *data, unsigned width, unsigned height, size_t pitch); interface LibRetro : Library { fun retro_set_video_refresh(cb: retro_video_refresh) } LibRetro.kt libretro.h
77. void retro_set_input_state(retro_input_state_t); Writing Bindings: Input State Callback
78. void retro_set_input_state(retro_input_state_t); typedef int16_t (*retro_input_state_t)( unsigned port, unsigned device, unsigned index, unsigned id); Writing Bindings: Input State Callback
79. interface retro_input_state : Callback { fun invoke( port: UInt, device: UInt, index: UInt, id: UInt): Short } void retro_set_input_state(retro_input_state_t); typedef int16_t (*retro_input_state_t)( unsigned port, unsigned device, unsigned index, unsigned id); interface LibRetro : Library { fun retro_set_input_state(cb: retro_input_state) } LibRetro.kt libretro.h Writing Bindings: Input State Callback
80. interface retro_input_state : Callback { fun invoke( port: UInt, device: UInt, index: UInt, id: UInt): Short } void retro_set_input_state(retro_input_state_t); typedef int16_t (*retro_input_state_t)( unsigned port, unsigned device, unsigned index, unsigned id); interface LibRetro : Library { fun retro_set_input_state(cb: retro_input_state) } LibRetro.kt libretro.h Writing Bindings: Input State Callback
81. #define RETRO_DEVICE_JOYPAD 1 #define RETRO_DEVICE_ID_JOYPAD_START 3 #define RETRO_DEVICE_ID_JOYPAD_UP 4 #define RETRO_DEVICE_ID_JOYPAD_DOWN 5 #define RETRO_DEVICE_ID_JOYPAD_LEFT 6 #define RETRO_DEVICE_ID_JOYPAD_RIGHT 7 const val RETRO_DEVICE_JOYPAD = 1 const val RETRO_DEVICE_ID_JOYPAD_START = 3 const val RETRO_DEVICE_ID_JOYPAD_UP = 4 const val RETRO_DEVICE_ID_JOYPAD_DOWN = 5 const val RETRO_DEVICE_ID_JOYPAD_LEFT = 6 const val RETRO_DEVICE_ID_JOYPAD_RIGHT = 7 LibRetro.kt libretro.h Writing Bindings: Input State Callback
82. void retro_run(void); interface LibRetro : Library { fun retro_run() } LibRetro.kt libretro.h Writing Bindings: Run Game Loop
83. class retro_game_info : Structure() { @JvmField var path: String? = null @JvmField var data: Pointer? = null @JvmField var size: SizeT = SizeT() @JvmField var meta: String? = null override fun getFieldOrder() = listOf("path", "data", "size", "meta") } interface retro_audio_sample_batch : Callback { fun invoke(data: Pointer, frames: SizeT): SizeT } interface retro_video_refresh : Callback { fun invoke(data: Pointer, width: UInt, height: UInt, pitch: SizeT) } interface retro_input_state : Callback { fun invoke(port: UInt, device: UInt, index: UInt, id: UInt): Short } interface retro_input_poll : Callback { fun invoke() } interface LibRetro : Library {AA fun retro_init() fun retro_load_game(game: retro_game_info): Boolean fun retro_set_audio_sample_batch(cb: retro_audio_sample_batch) fun retro_set_video_refresh(cb: retro_video_refresh) fun retro_set_input_state(cb: retro_input_state) fun retro_set_input_poll(cb: retro_input_poll) fun retro_run() }BB
84. libretro + JNA 1. Write library bindings. 2. Implement callbacks. 3. Call functions.
85. Implementing Callbacks: Audio private val audioSampleBatch = object : retro_audio_sample_batch { override fun invoke(data: Pointer, frames: SizeT): SizeT { }AA }BB
86. Implementing Callbacks: Audio private val audioBytesPerFrame = 4 // 16-bit stereo private val audioSampleBatch = object : retro_audio_sample_batch { override fun invoke(data: Pointer, frames: SizeT): SizeT { val length = frames * audioBytesPerFrame }AA }BB
87. Implementing Callbacks: Audio private val audioBytesPerFrame = 4 // 16-bit stereo private val audioSampleBatch = object : retro_audio_sample_batch { override fun invoke(data: Pointer, frames: SizeT): SizeT { val length = frames * audioBytesPerFrame val buffer = data.getByteArray(0, length) }AA }BB
88. Implementing Callbacks: Audio import android.media.AudioTrack private val audioTrack = AudioTrack.Builder() .setAudioFormat(AudioFormat.Builder() .setEncoding(AudioFormat.ENCODING_PCM_16BIT) .setSampleRate(32040) .setChannelMask(AudioFormat.CHANNEL_OUT_STEREO) .build()) .build() private val audioBytesPerFrame = 4 // 16-bit stereo private val audioSampleBatch = object : retro_audio_sample_batch { override fun invoke(data: Pointer, frames: SizeT): SizeT { val length = frames * audioBytesPerFrame val buffer = data.getByteArray(0, length) }AA }BB
89. Implementing Callbacks: Audio import android.media.AudioTrack private val audioTrack = AudioTrack.Builder() .setAudioFormat(AudioFormat.Builder() .setEncoding(AudioFormat.ENCODING_PCM_16BIT) .setSampleRate(32040) .setChannelMask(AudioFormat.CHANNEL_OUT_STEREO) .build()) .build() private val audioBytesPerFrame = 4 // 16-bit stereo private val audioSampleBatch = object : retro_audio_sample_batch { override fun invoke(data: Pointer, frames: SizeT): SizeT { val length = frames * audioBytesPerFrame val buffer = data.getByteArray(0, length) val written = audioTrack.write(buffer, 0, buffer.size) audioTrack.play() return SizeT(written) }AA }BB
90. Implementing Callbacks: Video private val videoRefresh = object : retro_video_refresh { override fun invoke(data: Pointer, width: UInt, height: UInt, pitch: SizeT) { }AA }BB
91. Implementing Callbacks: Video private val videoBytesPerPixel = 2 // RGB 565 private val videoRefresh = object : retro_video_refresh { override fun invoke(data: Pointer, width: UInt, height: UInt, pitch: SizeT) { val widthBytes = width * videoBytesPerPixel val totalBytes = width * height * videoBytesPerPixel }AA }BB
92. Implementing Callbacks: Video private val videoBytesPerPixel = 2 // RGB 565 private val videoRefresh = object : retro_video_refresh { override fun invoke(data: Pointer, width: UInt, height: UInt, pitch: SizeT) { val widthBytes = width * videoBytesPerPixel val totalBytes = width * height * videoBytesPerPixel val buffer = ByteArray(totalBytes) for (i in 0 until height.toInt()) { data.read(i * pitch.toLong(), buffer, i * widthBytes, widthBytes) }FF }AA }BB
93. Implementing Callbacks: Video import android.graphics.Bitmap private val videoBytesPerPixel = 2 // RGB 565 private val videoRefresh = object : retro_video_refresh { override fun invoke(data: Pointer, width: UInt, height: UInt, pitch: SizeT) { val widthBytes = width * videoBytesPerPixel val totalBytes = width * height * videoBytesPerPixel val buffer = ByteArray(totalBytes) for (i in 0 until height.toInt()) { data.read(i * pitch.toLong(), buffer, i * widthBytes, widthBytes) }FF val bitmap = Bitmap.createBitmap( width.toInt(), height.toInt(), Bitmap.Config.RGB_565) bitmap.copyPixelsFromBuffer(ByteBuffer.wrap(buffer)) }AA }BB
94. Implementing Callbacks: Video import android.graphics.Bitmap private val imageView by lazy { findViewById<ImageView>(R.id.imageView) } private val videoBytesPerPixel = 2 // RGB 565 private val videoRefresh = object : retro_video_refresh { override fun invoke(data: Pointer, width: UInt, height: UInt, pitch: SizeT) { val widthBytes = width * videoBytesPerPixel val totalBytes = width * height * videoBytesPerPixel val buffer = ByteArray(totalBytes) for (i in 0 until height.toInt()) { data.read(i * pitch.toLong(), buffer, i * widthBytes, widthBytes) }FF val bitmap = Bitmap.createBitmap( width.toInt(), height.toInt(), Bitmap.Config.RGB_565) bitmap.copyPixelsFromBuffer(ByteBuffer.wrap(buffer)) imageView.post { imageView.setImageBitmap(bitmap) } }AA }BB
95. Implementing Callbacks: Input State private val inputState = object : retro_input_state { override fun invoke(port: UInt, device: UInt, index: UInt, id: UInt): Short { }BB }ZZ
96. Implementing Callbacks: Input State private val inputState = object : retro_input_state { override fun invoke(port: UInt, device: UInt, index: UInt, id: UInt): Short { }BB }ZZ // TODO: Multiplayer support if (port.toInt() != 0) { return 0AA }AA
97. Implementing Callbacks: Input State private val inputState = object : retro_input_state { override fun invoke(port: UInt, device: UInt, index: UInt, id: UInt): Short { if (port.toInt() != 0) { return 0AA }AA }BB }ZZ if (device.toInt() != RETRO_DEVICE_JOYPAD) { return 0JJ }DD
98. Implementing Callbacks: Input State private val inputState = object : retro_input_state { override fun invoke(port: UInt, device: UInt, index: UInt, id: UInt): Short { if (port.toInt() != 0) { return 0 }AA if (device.toInt() != RETRO_DEVICE_JOYPAD) { return 0JJ }DD }BB }ZZ private val pressedButtons = mutableSetOf<Int>()
99. Implementing Callbacks: Input State private val pressedButtons = mutableSetOf<Int>() private val inputState = object : retro_input_state { override fun invoke(port: UInt, device: UInt, index: UInt, id: UInt): Short { if (port.toInt() != 0) { return 0 RR }AA if (device.toInt() != RETRO_DEVICE_JOYPAD) { return 0 GG }DD }BB }ZZ val isPressed = when (id.toInt()) { RETRO_DEVICE_ID_JOYPAD_START -> pressedButtons.contains(KeyEvent.KEYCODE_BUTTON_START) RETRO_DEVICE_ID_JOYPAD_UP -> pressedButtons.contains(KeyEvent.KEYCODE_DPAD_UP) RETRO_DEVICE_ID_JOYPAD_DOWN -> pressedButtons.contains(KeyEvent.KEYCODE_DPAD_DOWN) RETRO_DEVICE_ID_JOYPAD_LEFT -> pressedButtons.contains(KeyEvent.KEYCODE_DPAD_LEFT) RETRO_DEVICE_ID_JOYPAD_RIGHT -> pressedButtons.contains(KeyEvent.KEYCODE_DPAD_RIGHT) else -> false } return if (isPressed) 1 else 0 import android.view.KeyEvent
100. Implementing Callbacks: Input State private val inputState = object : retro_input_state { override fun invoke(port: UInt, device: UInt, index: UInt, id: UInt): Short { if (port.toInt() != 0) { return 0 RR }AA if (device.toInt() != RETRO_DEVICE_JOYPAD) { return 0 GG }DD }BB }ZZ val isPressed = when (id.toInt()) { RETRO_DEVICE_ID_JOYPAD_START -> pressedButtons.contains(KeyEvent.KEYCODE_BUTTON_START) RETRO_DEVICE_ID_JOYPAD_UP -> pressedButtons.contains(KeyEvent.KEYCODE_DPAD_UP) RETRO_DEVICE_ID_JOYPAD_DOWN -> pressedButtons.contains(KeyEvent.KEYCODE_DPAD_DOWN) RETRO_DEVICE_ID_JOYPAD_LEFT -> pressedButtons.contains(KeyEvent.KEYCODE_DPAD_LEFT) RETRO_DEVICE_ID_JOYPAD_RIGHT -> pressedButtons.contains(KeyEvent.KEYCODE_DPAD_RIGHT) else -> false } return if (isPressed) 1 else 0 import android.view.KeyEvent private val pressedButtons = mutableSetOf<Int>()
101. Implementing Callbacks: Input State import android.view.KeyEvent private val pressedButtons = mutableSetOf<Int>() override fun dispatchKeyEvent(event: KeyEvent): Boolean { }ZZ
102. Implementing Callbacks: Input State private val pressedButtons = mutableSetOf<Int>() override fun dispatchKeyEvent(event: KeyEvent): Boolean { }ZZ import android.view.KeyEvent super.dispatchKeyEvent(event) when (event.action) { KeyEvent.ACTION_DOWN -> pressedButtons.add(event.keyCode) KeyEvent.ACTION_UP -> pressedButtons.remove(event.keyCode) } return true
103. libretro + JNA 1. Write library bindings. 2. Implement callbacks. 3. Call functions.
104. Calling Functions val lib = Native.loadLibrary(
 "snes9x_libretro_android",
 LibRetro::class.java) lib.retro_set_audio_sample_batch(audioSampleBatch)
 lib.retro_set_video_refresh(videoRefresh)
 lib.retro_set_input_poll(inputPoll)
 lib.retro_set_input_state(inputState)
 lib.retro_init() val gameInfo = retro_game_info()
 gameInfo.path = "/sdcard/allstars.smc"
 lib.retro_load_game(gameInfo) fixedRateTimer(period = 1000L / 60L) {
 lib.retro_run()
 }
106. wat libc F Fatal signal 11 (SIGSEGV), code 1, fault addr 0x0 in tid 12676 ( DEBUG F #00 pc 00000000 <unknown> F #01 pc 00010fc9 /data/app/com.codebutler.funwithnativecode-n1T9 F #02 pc 00010c40 /data/app/com.codebutler.funwithnativecode-n1T9 F #03 pc 000051e0 /data/app/com.codebutler.funwithnativecode-n1T9 F #04 pc 00007c8f /data/app/com.codebutler.funwithnativecode-n1T9 F #05 pc 0063ec67 /system/lib/libart.so (art_quick_generic_jni_tr F #06 pc 00638ea2 /system/lib/libart.so (art_quick_invoke_static_ F #07 pc 00112b92 /system/lib/libart.so (_ZN3art9ArtMethod6Invoke F #08 pc 003231ff /system/lib/libart.so (_ZN3art11interpreter34Ar F #09 pc 0031bde1 /system/lib/libart.so (_ZN3art11interpreter6DoC F #10 pc 0061faf4 /system/lib/libart.so (MterpInvokeStatic+484)
107. wat
108. wat
109. interface retro_environment : Callback { fun invoke(cmd: UInt, data: Pointer): Boolean }EE LibRetro.kt libretro.h interface LibRetro : Library { } void retro_set_environment(retro_environment_t); typedef bool (*retro_environment_t)(unsigned cmd, void *data); Writing Bindings: Environment Callback fun retro_set_environment(cb: retro_environment)
110. class retro_game_info : Structure() { @JvmField var path: String? = null @JvmField var data: Pointer? = null @JvmField var size: SizeT = SizeT() @JvmField var meta: String? = null override fun getFieldOrder() = listOf("path", "data", "size", "meta") } interface retro_audio_sample_batch : Callback { fun invoke(data: Pointer, frames: SizeT): SizeT } interface retro_video_refresh : Callback { fun invoke(data: Pointer, width: UInt, height: UInt, pitch: SizeT) } interface retro_input_state : Callback { fun invoke(port: UInt, device: UInt, index: UInt, id: UInt): Short } interface retro_input_poll : Callback { fun invoke() } interface LibRetro : Library {AA fun retro_init() fun retro_load_game(game: retro_game_info): Boolean fun retro_set_audio_sample_batch(cb: retro_audio_sample_batch) fun retro_set_video_refresh(cb: retro_video_refresh) fun retro_set_input_state(cb: retro_input_state) fun retro_set_input_poll(cb: retro_input_poll) fun retro_run() }BB fun retro_set_environment(cb: retro_environment) interface retro_environment : Callback { fun invoke(cmd: UInt, data: Pointer): Boolean }EE
111. class retro_game_info : Structure() { @JvmField var path: String? = null @JvmField var data: Pointer? = null @JvmField var size: SizeT = SizeT() @JvmField var meta: String? = null override fun getFieldOrder() = listOf("path", "data", "size", "meta") } interface retro_environment : Callback { fun invoke(cmd: UInt, data: Pointer): Boolean } interface retro_audio_sample_batch : Callback { fun invoke(data: Pointer, frames: SizeT): SizeT } interface retro_video_refresh : Callback { fun invoke(data: Pointer, width: UInt, height: UInt, pitch: SizeT) } interface retro_input_state : Callback { fun invoke(port: UInt, device: UInt, index: UInt, id: UInt): Short } interface retro_input_poll : Callback { fun invoke() } interface LibRetro : Library {AA fun retro_init() fun retro_load_game(game: retro_game_info): Boolean fun retro_set_environment(cb: retro_input_poll) fun retro_set_audio_sample_batch(cb: retro_audio_sample_batch) fun retro_set_video_refresh(cb: retro_video_refresh) fun retro_set_input_state(cb: retro_input_state) fun retro_set_input_poll(cb: retro_input_poll) fun retro_run() }BB
112. private val environment = object : retro_environment { override fun invoke(cmd: UInt, data: Pointer): Boolean = false } Implementing Callbacks: Environment
113. val lib = Native.loadLibrary( "snes9x_libretro_android", LibRetro::class.java) lib.retro_set_audio_sample_batch(audioSampleBatch) lib.retro_set_video_refresh(videoRefresh) lib.retro_set_input_poll(inputPoll) lib.retro_set_input_state(inputState) lib.retro_init() val gameInfo = retro_game_info() gameInfo.path = "/sdcard/allstars.smc" lib.retro_load_game(gameInfo) fixedRateTimer(period = 1000L / 60L) { lib.retro_run() }AA
114. val lib = Native.loadLibrary( "snes9x_libretro_android", LibRetro::class.java) lib.retro_set_audio_sample_batch(audioSampleBatch) lib.retro_set_video_refresh(videoRefresh) lib.retro_set_input_poll(inputPoll) lib.retro_set_input_state(inputState) lib.retro_init() val gameInfo = retro_game_info() gameInfo.path = "/sdcard/allstars.smc" lib.retro_load_game(gameInfo) fixedRateTimer(period = 1000L / 60L) { lib.retro_run() }AA lib.retro_set_environment(environment)
117. val lib = Native.loadLibrary( "snes9x_libretro_android", LibRetro::class.java) lib.retro_set_environment(environment) lib.retro_set_audio_sample_batch(audioSampleBatch) lib.retro_set_video_refresh(videoRefresh) lib.retro_set_input_poll(inputPoll) lib.retro_set_input_state(inputState) lib.retro_init() val gameInfo = retro_game_info() gameInfo.path = "/sdcard/allstars.smc" lib.retro_load_game(gameInfo) fixedRateTimer(period = 1000L / 60L) { lib.retro_run() }
118. val lib = Native.loadLibrary( LibRetro::class.java) lib.retro_set_environment(environment) lib.retro_set_audio_sample_batch(audioSampleBatch) lib.retro_set_video_refresh(videoRefresh) lib.retro_set_input_poll(inputPoll) lib.retro_set_input_state(inputState) lib.retro_init() val gameInfo = retro_game_info() lib.retro_load_game(gameInfo) fixedRateTimer(period = 1000L / 60L) { lib.retro_run() } "genesis_plus_gx_libretro_android", gameInfo.path = "/sdcard/sonic3.md"
120. MY DREAM APP...
121. MY APP...!
123. ODYSSEY github.com/codebutler/odyssey Current Features 7 Console Systems Early Leanback UI Controller Support Game Covert Art Game Save/Restore WebDAV Future Features More Console Systems Better UI Local Multiplayer Game State Save/Restore Dropbox/GDrive Cheat Codes Internet Multiplayer Twitch/YouTube (Named after the Magnavox Odyssey, the first commercial home video game console released in 1972)
124. THANKS! Slides & Code bit.ly/FunWithNativeCode Follow Me @codebutler