updates

Author: keynmol

.github/workflows/ci.yml

@@ -0,0 +1,29 @@
+name: CI
+on:
+  push:
+    branches: ["main"]
+    tags: ["v*"]
+  pull_request:
+    branches: ["*"]
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-22.04, macos-14, macos-13]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin' 
+          java-version: '23'
+
+      - uses: coursier/cache-action@v6
+
+      - uses: VirtusLab/scala-cli-setup@main
+
+      - name: Test
+        run: make run

README.md

@@ -0,0 +1,9 @@
+## Call Scala Native from Java using FFM
+
+Demonstration project for my [blog post](https://blog.indoorvivants.com/2025-02-16-scala-native-from-java-via-ffm).
+
+Uses Scala CLI.
+
+Run with `make run`. 
+
+Other commands will require both [jextract](https://github.com/openjdk/jextract) and [sn-bindgen](https://sn-bindgen.indoorvivants.com/) to be installed.

interface.h

@@ -1,15 +1,8 @@
-
-typedef enum {
-  MULTIPLY = 1,
-  ADD = 2
-} myscalalib_operation;
+typedef enum { MULTIPLY = 1, ADD = 2 } myscalalib_operation;
 
 typedef struct {
   myscalalib_operation op;
-  char* label;
+  char *label;
 } myscalalib_config;
 
-
-extern float myscalalib_run(myscalalib_config* config, float left, float right);
-
-extern int ScalaNativeInit(void);
+extern float myscalalib_run(myscalalib_config *config, float left, float right);

java-side/Main.java

@@ -15,12 +15,7 @@ public static void main(String[] args) {
 		} else {
 			dylibPath = args[0];
 		}
-		var p = Paths.get(dylibPath).toAbsolutePath().toString();
-
-		System.load(p);
-
-		// Make sure Scala Native GC is initialised correctly!
-		assert (interface_h.ScalaNativeInit() == 0);
+		System.load(Paths.get(dylibPath).toAbsolutePath().toString());
 
 		// Run exported functions
 		try (Arena arena = Arena.ofConfined()) {
@@ -33,7 +28,6 @@ public static void main(String[] args) {
 			myscalalib_config.label(config, arena.allocateFrom("Second"));
 			myscalalib_config.op(config, interface_h.MULTIPLY());
 			interface_h.myscalalib_run(config, 50.0f, 10.0f);
-
 		}
 
 	}

java-side/myscalalib_bindings/interface_h.java

@@ -146,61 +146,5 @@ public static float myscalalib_run(MemorySegment config, float left, float right
            throw new AssertionError("should not reach here", ex$);
         }
     }
-
-    private static class ScalaNativeInit {
-        public static final FunctionDescriptor DESC = FunctionDescriptor.of(
-            interface_h.C_INT    );
-
-        public static final MemorySegment ADDR = interface_h.findOrThrow("ScalaNativeInit");
-
-        public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
-    }
-
-    /**
-     * Function descriptor for:
-     * {@snippet lang=c :
-     * extern int ScalaNativeInit()
-     * }
-     */
-    public static FunctionDescriptor ScalaNativeInit$descriptor() {
-        return ScalaNativeInit.DESC;
-    }
-
-    /**
-     * Downcall method handle for:
-     * {@snippet lang=c :
-     * extern int ScalaNativeInit()
-     * }
-     */
-    public static MethodHandle ScalaNativeInit$handle() {
-        return ScalaNativeInit.HANDLE;
-    }
-
-    /**
-     * Address for:
-     * {@snippet lang=c :
-     * extern int ScalaNativeInit()
-     * }
-     */
-    public static MemorySegment ScalaNativeInit$address() {
-        return ScalaNativeInit.ADDR;
-    }
-
-    /**
-     * {@snippet lang=c :
-     * extern int ScalaNativeInit()
-     * }
-     */
-    public static int ScalaNativeInit() {
-        var mh$ = ScalaNativeInit.HANDLE;
-        try {
-            if (TRACE_DOWNCALLS) {
-                traceDowncall("ScalaNativeInit");
-            }
-            return (int)mh$.invokeExact();
-        } catch (Throwable ex$) {
-           throw new AssertionError("should not reach here", ex$);
-        }
-    }
 }
 

java-side/myscalalib_bindings/myscalalib_config.java

@@ -30,7 +30,7 @@ public class myscalalib_config {
         interface_h.C_INT.withName("op"),
         MemoryLayout.paddingLayout(4),
         interface_h.C_POINTER.withName("label")
-    ).withName("$anon$7:9");
+    ).withName("$anon$3:9");
 
     /**
      * The layout of this struct

scala-native-side/interface.scala

@@ -75,12 +75,13 @@ object functions extends ExportedFunctions:
    * [bindgen] header: interface.h
   */
   @exported
-  override def myscalalib_run(config : Ptr[myscalalib_config], left : Float, right : Float): Float = myscalalib.impl.Implementations.myscalalib_run(config, left, right)
+  override def myscalalib_run(config : Ptr[myscalalib_config], left : Float, right : Float): Float = 
+    myscalalib.impl.Implementations.myscalalib_run(config, left, right)
 
 object types:
   export _root_.myscalalib.structs.*
   export _root_.myscalalib.enumerations.*
 
 object all:
   export _root_.myscalalib.enumerations.myscalalib_operation
-  export _root_.myscalalib.structs.myscalalib_config
+  export _root_.myscalalib.structs.myscalalib_config

scala-native-side/main.scala

@@ -1,3 +1,9 @@
+//> using platform scala-native
+//> using scala 3.6.3
+//> using nativeVersion 0.5.6
+//> using nativeTarget dynamic
+//> using dep com.outr::scribe::3.16.0
+
 package myscalalib.impl
 
 import scalanative.unsafe.*