libretro/emulators/jl-mod.yml

emulator: JL-Mod
type: standalone
core_classification: community_fork
source: "https://github.com/woesss/JL-Mod"
upstream: "https://github.com/nikita36078/J2ME-Loader"
author: "Yury Kharchenko"
profiled_date: "2026-08-11"
source_commit: "f723a190c0bdb44b31c3bc0ead6f8665c7ea517d"
core_version: "0.87.1"
display_name: "Mobile - J2ME (JL-Mod)"
cores:
  - jl-mod
  - "JL-MOD"
systems:
  - j2me
mode: standalone

notes: |
  MIDP/CLDC runtime for Android, package ru.woesss.j2meloader. A .jar, .jad or
  .kjx is instrumented and converted to Dalvik bytecode at install time, then
  runs against the javax.microedition classes compiled into the app, so no
  device firmware is read. Two build flavors share the sources: emulator, the
  published application, and midlet, which packs a single ported J2ME
  application and is the only one reading MIDLET-META-INF/MANIFEST.MF.
  ref: app/src/main/java/ru/woesss/j2me/installer/AppInstaller.java:127-146,
       app/build.gradle.kts:67-93,
       app/src/main/java/javax/microedition/shell/MicroLoader.java:127-146

  Three 3D stacks are compiled in, each with its own shaders and native code:
  JSR-184 M3G on GLES 1.1 (libjavam3g.so), Mascot Capsule v3 (libmicro3d.so with
  the tex, color, simple and sprite programs) and Nokia M3D (libgles_utils.so
  with the m3d pair). MIDI playback goes to the Android synthesizer unless a
  sound bank is selected, which routes it to Sonivox EAS or TinySoundFont, both
  driven by Oboe.
  ref: app/src/main/cpp/Android.mk:1,
       app/src/main/java/ru/woesss/j2me/mmapi/synth/SynthPluginFactory.java:34-52

  Assets are read through ContextHolder.getAssetAsString, which rethrows an
  IOException as RuntimeException instead of degrading, so an absent asset ends
  the code path that reads it.
  ref: app/src/main/java/javax/microedition/util/ContextHolder.java:178-192

  The working directory holds converted/, configs/, templates/ and data/, all
  written by the app, plus shaders/, soundbanks/ and skins/, created empty at
  first run and read from. data/ carries the RMS record stores and backs the
  JSR-75 c: drive.
  ref: app/src/main/java/ru/playsoftware/j2meloader/config/Config.java:41-58,
       app/src/main/java/ru/playsoftware/j2meloader/util/FileUtils.java:162-171,
       app/src/main/java/javax/microedition/shell/MicroLoader.java:221-227

files:
  - name: system.props
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Default microedition system properties"
    note: "Read from assets/defaults when a profile is created, when the config screen has no stored value and when updateSystemProperties fills the field. Each line becomes a System.setProperty and MidletSystem.setProperty pair at MIDlet startup, carrying microedition.configuration, microedition.platform, the JSR version strings and the vendor identity values."
    source_ref: "app/src/main/java/ru/playsoftware/j2meloader/config/ProfileModel.java:211, app/src/main/java/ru/playsoftware/j2meloader/config/ConfigActivity.java:644, app/src/main/java/ru/playsoftware/j2meloader/config/ProfilesManager.java:189, app/src/main/java/javax/microedition/shell/MicroLoader.java:246-252"

  - name: simple.vsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Vertex shader for the screen blitter"
    note: "Compiled when the GL surface is created and no user shader is selected. Graphics mode 1 is the default, so this is the standard display path. Also compiled as the Simple program of the Mascot Capsule renderer."
    source_ref: "app/src/main/java/javax/microedition/lcdui/graphics/ShaderProgram.java:34, app/src/main/java/javax/microedition/lcdui/graphics/ShaderProgram.java:58, app/src/main/java/javax/microedition/lcdui/Canvas.java:744, app/src/main/java/ru/playsoftware/j2meloader/config/ProfileModel.java:193, app/src/main/java/ru/woesss/j2me/micro3d/Program.java:216"

  - name: simple.fsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Fragment shader for the screen blitter"
    note: "Paired with simple.vsh. createProgram returning -1 raises RuntimeException at surface creation."
    source_ref: "app/src/main/java/javax/microedition/lcdui/graphics/ShaderProgram.java:35, app/src/main/java/javax/microedition/lcdui/graphics/ShaderProgram.java:59-63, app/src/main/java/ru/woesss/j2me/micro3d/Program.java:217"

  - name: color.vsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Vertex shader for untextured Mascot Capsule geometry"
    note: "Program.create builds the tex, color, simple and sprite programs together the first time the Mascot Capsule renderer draws, so all four pairs are read on the first micro3d frame."
    source_ref: "app/src/main/java/ru/woesss/j2me/micro3d/Program.java:150, app/src/main/java/ru/woesss/j2me/micro3d/Program.java:53-58, app/src/main/java/ru/woesss/j2me/micro3d/Render.java:156"

  - name: color.fsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Fragment shader for untextured Mascot Capsule geometry"
    note: "Carries the sphere map, toon threshold and primitive colour uniforms of the Color program."
    source_ref: "app/src/main/java/ru/woesss/j2me/micro3d/Program.java:151, app/src/main/java/ru/woesss/j2me/micro3d/Program.java:162-178"

  - name: tex.vsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Vertex shader for textured Mascot Capsule geometry"
    note: "Built by Program.create alongside the other three pairs."
    source_ref: "app/src/main/java/ru/woesss/j2me/micro3d/Program.java:233, app/src/main/java/ru/woesss/j2me/micro3d/Program.java:53-58"

  - name: tex.fsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Fragment shader for textured Mascot Capsule geometry"
    note: "Carries the texture size, sphere map and toon uniforms of the Tex program."
    source_ref: "app/src/main/java/ru/woesss/j2me/micro3d/Program.java:234, app/src/main/java/ru/woesss/j2me/micro3d/Program.java:253-271"

  - name: sprite.vsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Vertex shader for Mascot Capsule sprites"
    note: "Built by Program.create alongside the other three pairs."
    source_ref: "app/src/main/java/ru/woesss/j2me/micro3d/Program.java:313, app/src/main/java/ru/woesss/j2me/micro3d/Program.java:53-58"

  - name: sprite.fsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Fragment shader for Mascot Capsule sprites"
    note: "Carries the texture size and colour key uniforms of the Sprite program."
    source_ref: "app/src/main/java/ru/woesss/j2me/micro3d/Program.java:314, app/src/main/java/ru/woesss/j2me/micro3d/Program.java:330-337"

  - name: m3d.vsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Vertex shader for the Nokia M3D renderer"
    note: "Compiled when a MIDlet first binds a com.nokia.mid.m3d context. Carries the position, texture coordinate and matrix inputs."
    source_ref: "app/src/main/java/com/nokia/mid/m3d/ShaderProgram.java:28, app/src/main/java/com/nokia/mid/m3d/ShaderProgram.java:38, app/src/main/java/com/nokia/mid/m3d/M3D.java:132"

  - name: m3d.fsh
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Fragment shader for the Nokia M3D renderer"
    note: "Paired with m3d.vsh. A link failure raises RuntimeException in the constructor."
    source_ref: "app/src/main/java/com/nokia/mid/m3d/ShaderProgram.java:29, app/src/main/java/com/nokia/mid/m3d/ShaderProgram.java:39-76"

  - name: patches.bin
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Binary class patches applied during MIDlet conversion"
    note: "Index of class CRC32 to patch offset, read by the static field initializer of AndroidProducer and again for each matching class the dexer instruments. A read failure outside end of file is rethrown as RuntimeException, which breaks class initialization and therefore every conversion. Patch entries are applied by the SRC/EXT/FWD/BWD opcode stream of BinaryPatcher."
    source_ref: "dexlib/src/main/java/org/microemu/android/asm/AndroidProducer.java:41, dexlib/src/main/java/org/microemu/android/asm/AndroidProducer.java:62-90, dexlib/src/main/java/com/android/dx/command/dexer/Main.java:468, dexlib/src/main/java/org/microemu/android/asm/BinaryPatcher.java:49-71"

  - name: licenses.html
    system: j2me
    required: false
    bundled: true
    category: game_data
    description: "Third party licence text of the about screen"
    note: "Read when the licences dialog is opened and shown as HTML. Emulation never touches it."
    source_ref: "app/src/main/java/ru/playsoftware/j2meloader/info/LicensesDialogFragment.java:35"

  - name: appcenter.cer
    system: j2me
    required: false
    bundled: true
    category: game_data
    description: "X.509 certificate for the crash report endpoint"
    note: "Named as an ACRA certificate path only when the crash sender is configured on Android 4.1 through 4.4, where TLSv1.2 is forced. Every other release uses the default socket factory."
    source_ref: "app/src/main/java/ru/playsoftware/j2meloader/crashes/AppCenterSender.java:68-75"

  - name: libc++_shared.so
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "NDK C++ runtime for the native modules"
    note: "Named ahead of every other native library, in the static initializers of GLESUtils and micro3d Utils, in the M3G toolkit init and in both synthesizer classes."
    source_ref: "app/src/main/java/ru/woesss/gles/GLESUtils.java:31, app/src/main/java/ru/woesss/j2me/micro3d/Utils.java:103, app/src/main/java/javax/microedition/m3g/Platform.java:86, app/src/main/java/ru/woesss/j2me/mmapi/synth/eas/LibEAS.java:70, app/src/main/java/ru/woesss/j2me/mmapi/synth/tsf/LibTSF.java:70"

  - name: libgles_utils.so
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "GLES blit routines for the Nokia M3D and Mexa OpenGL surfaces"
    note: "Loaded from the static initializer of GLESUtils, so the first blit brings it in. Holds the GLES1 and GLES2 bitmap blits."
    source_ref: "app/src/main/java/ru/woesss/gles/GLESUtils.java:30-33, app/src/main/java/com/nokia/mid/m3d/M3D.java:323, app/src/main/java/com/mexa/opgl/OpglGraphics.java:493, app/src/main/cpp/gles_utils/Android.mk:5-11"

  - name: libjavam3g.so
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "JSR-184 M3G engine"
    note: "Named by System.loadLibrary outside any catch, the first time the toolkit reports the UI thread available. Built by ndkBuild from the m3g sources against GLES 1.1."
    source_ref: "app/src/main/java/javax/microedition/m3g/Platform.java:85-89, app/src/main/java/javax/microedition/m3g/Interface.java:314, app/src/main/cpp/m3g/Android.mk:5-15"

  - name: libmicro3d.so
    system: j2me
    required: true
    bundled: true
    category: game_data
    description: "Mascot Capsule vertex and buffer routines"
    note: "Loaded from the static initializer of Utils, so the first Mascot Capsule call brings it in. Holds fillBuffer, glReadPixels and the bone transform."
    source_ref: "app/src/main/java/ru/woesss/j2me/micro3d/Utils.java:97-105, app/src/main/cpp/micro3d/Android.mk:5-10"

  - name: liboboe.so
    system: j2me
    required: false
    bundled: true
    category: game_data
    description: "Audio output stream of the sound bank synthesizers"
    note: "Named by both synthesizer classes ahead of their own libraries. Reached only when a sound bank is selected, and SynthPluginFactory catches the load failure and falls back to the Android synthesizer."
    source_ref: "app/src/main/java/ru/woesss/j2me/mmapi/synth/eas/LibEAS.java:71, app/src/main/java/ru/woesss/j2me/mmapi/synth/tsf/LibTSF.java:71, app/src/main/java/ru/woesss/j2me/mmapi/synth/SynthPluginFactory.java:40-53"

  - name: libmmapi_common.so
    system: j2me
    required: false
    bundled: true
    category: game_data
    description: "Shared player and listener code of the synthesizer plugins"
    note: "Named by both synthesizer classes ahead of their own libraries. Same fallback as liboboe.so."
    source_ref: "app/src/main/java/ru/woesss/j2me/mmapi/synth/eas/LibEAS.java:72, app/src/main/java/ru/woesss/j2me/mmapi/synth/tsf/LibTSF.java:72, app/src/main/cpp/mmapi_common/Android.mk:5-12"

  - name: libmmapi_eas.so
    system: j2me
    required: false
    bundled: true
    category: game_data
    description: "Sonivox EAS synthesizer"
    note: "Loaded from the static initializer of LibEAS when a sound bank is selected. Links the sonivox wavetable engine statically and reads the bank as a DLS collection. A failure leaves the TinySoundFont plugin or the Android synthesizer."
    source_ref: "app/src/main/java/ru/woesss/j2me/mmapi/synth/eas/LibEAS.java:69-74, app/src/main/cpp/mmapi_eas/Android.mk:5-22, app/src/main/cpp/sonivox/Android.mk:134"

  - name: libmmapi_tsf.so
    system: j2me
    required: false
    bundled: true
    category: game_data
    description: "TinySoundFont synthesizer"
    note: "Loaded from the static initializer of LibTSF when a sound bank is selected. Reads the bank as a SoundFont and plays standard MIDI files. A failure leaves the EAS plugin or the Android synthesizer."
    source_ref: "app/src/main/java/ru/woesss/j2me/mmapi/synth/tsf/LibTSF.java:69-74, app/src/main/cpp/mmapi_tsf/Android.mk:5-11"

  - name: "<soundbank>.dls"
    path: "soundbanks/<soundbank>.dls"
    system: j2me
    required: false
    unsourceable: "user supplied, no canonical file"
    category: game_data
    description: "DLS sound bank for MIDI playback"
    note: "The config screen lists every regular file in the sound banks directory with no extension filter, and the selected name is kept as a path when the file exists. EAS_LoadDLSCollection reads it with the header search flag off; a rejected file throws and the plugin is skipped."
    source_ref: "app/src/main/java/ru/playsoftware/j2meloader/config/ConfigActivity.java:318-337, app/src/main/java/javax/microedition/shell/MicroLoader.java:272-274, app/src/main/cpp/mmapi_eas/eas_player.cpp:112-126"

  - name: "<soundbank>.sf2"
    path: "soundbanks/<soundbank>.sf2"
    system: j2me
    required: false
    unsourceable: "user supplied, no canonical file"
    category: game_data
    description: "SoundFont sound bank for MIDI playback"
    note: "Same selection path as the DLS bank. tsf_load_filename parses it, and a null result throws IllegalArgumentException so the plugin is skipped. Only standard MIDI files are played through this synthesizer."
    source_ref: "app/src/main/java/ru/playsoftware/j2meloader/config/ConfigActivity.java:318-337, app/src/main/cpp/mmapi_tsf/tsf_player.cpp:87-94, app/src/main/cpp/mmapi_tsf/tsf_player_jni.cpp:15-27"

  - name: "<skin>"
    path: "skins/<skin>"
    system: j2me
    required: false
    unsourceable: "user supplied, no canonical file"
    category: game_data
    description: "Background image drawn behind the virtual screen"
    note: "Any image format Android can decode. Decoded twice, once for bounds and once downsampled to the display, and an undecodable file leaves the layer unset. A rectangular area filled with transparent black is taken as the screen placement."
    source_ref: "app/src/main/java/ru/playsoftware/j2meloader/config/ConfigActivity.java:297-316, app/src/main/java/javax/microedition/lcdui/skin/SkinLayer.java:81-111, app/src/main/java/javax/microedition/shell/MicroLoader.java:276-278"

  - name: "<shader>.ini"
    path: "shaders/<shader>.ini"
    system: j2me
    required: false
    unsourceable: "user supplied, no canonical file"
    category: game_data
    description: "Shader descriptor read from the emulator directory"
    note: "The config screen creates the shaders directory, keeps every file ending in .ini and parses it as sections opened by a bracketed name, retaining the entries that name both a Vertex and a Fragment file. Name, Author, OutputResolution, Upscaling and four SettingName/SettingDefaultValue/SettingMinValue/SettingStep groups are also read, which is the PPSSPP post-processing descriptor format."
    source_ref: "app/src/main/java/ru/playsoftware/j2meloader/config/ConfigActivity.java:403-464, app/src/main/java/ru/playsoftware/j2meloader/config/ShaderInfo.java:101-207"

  - name: "<shader>.vsh"
    path: "shaders/<shader>.vsh"
    system: j2me
    required: false
    unsourceable: "user supplied, no canonical file"
    category: game_data
    description: "Vertex shader named by a descriptor"
    note: "Read whole from the shaders directory when the selected filter names it, then compiled in place of the built-in blitter. An unreadable file yields an empty string, the program fails to build and the bundled default is used after a toast."
    source_ref: "app/src/main/java/javax/microedition/lcdui/graphics/ShaderProgram.java:44-56, app/src/main/java/javax/microedition/shell/MicroLoader.java:263-266, app/src/main/java/ru/playsoftware/j2meloader/util/FileUtils.java:152-160"

  - name: "<shader>.fsh"
    path: "shaders/<shader>.fsh"
    system: j2me
    required: false
    unsourceable: "user supplied, no canonical file"
    category: game_data
    description: "Fragment shader named by a descriptor"
    note: "Paired with the vertex file of the same descriptor. Four float uniforms from the descriptor settings are pushed to it at surface creation."
    source_ref: "app/src/main/java/javax/microedition/lcdui/graphics/ShaderProgram.java:44-56, app/src/main/java/javax/microedition/lcdui/Canvas.java:753-754"