Add direct mapping and SKIP EXTERN tests

Package.swift

@@ -6,14 +6,14 @@ let package = Package(
     defaultLocalization: "en",
     platforms: [.iOS(.v16), .macOS(.v13), .tvOS(.v16), .watchOS(.v9), .macCatalyst(.v16)],
     products: [
-        .library(name: "SkipFFI", type: .dynamic, targets: ["SkipFFI"]),
+        .library(name: "SkipFFI", targets: ["SkipFFI"]),
     ],
     dependencies: [
-        .package(url: "https://source.skip.tools/skip.git", from: "0.7.16"),
-        .package(url: "https://source.skip.tools/skip-lib.git", from: "0.5.0")
+        .package(url: "https://source.skip.tools/skip.git", from: "0.7.30"),
+        .package(url: "https://source.skip.tools/skip-foundation.git", from: "0.3.7")
     ],
     targets: [
-        .target(name: "SkipFFI", dependencies: [.product(name: "SkipLib", package: "skip-lib")], plugins: [.plugin(name: "skipstone", package: "skip")]),
+        .target(name: "SkipFFI", dependencies: [.product(name: "SkipFoundation", package: "skip-foundation")], plugins: [.plugin(name: "skipstone", package: "skip")]),
         .testTarget(name: "SkipFFITests", dependencies: ["SkipFFI", .product(name: "SkipTest", package: "skip")], plugins: [.plugin(name: "skipstone", package: "skip")]),
     ]
 )

README.md

@@ -8,7 +8,7 @@ On the Kotlin side, SkipFFI uses the Java Native Access ([JNA](https://github.co
 library to simulate Swift types like `Swift.OpaquePointer` as `com.sun.jna.Pointer` pointer references, 
 and implements `Swift.withUnsafeMutablePointer` using a `com.sun.jna.ptr.PointerByReference` on the Java side.
 
-This capability is used by Skip frameworks like [SkipScript](https://source.skip.tools/skip-script) to 
+This capability is used by Skip frameworks like [SkipSQL](https://source.skip.tools/skip-sql) and [SkipScript](https://source.skip.tools/skip-script) to 
 provide a unified API to underlying native C APIs on both Darwin and Android.
 
 ## Example

Sources/SkipFFI/SkipFFI.swift

@@ -23,4 +23,5 @@ public func String(cString: OpaquePointer) -> String {
     cString.getString(0)
 }
 
+
 #endif

Tests/SkipFFITests/SkipFFITests.swift

@@ -47,6 +47,11 @@ final class SkipFFITests: XCTestCase {
         XCTAssertNil(Darwin.getenv("PATH_DOES_NOT_EXIST"), "non-existent key should not return a value for getenv")
     }
 
+    func testDarwinDirectMappingJNA() throws {
+        let dd = DarwinDirect()
+        XCTAssertEqual(12, dd.abs(-12))
+    }
+
     func testSQLiteJNA() throws {
         #if SKIP
         // You may set the system property jna.debug_load=true to make JNA print the steps of its library search to the console.
@@ -117,6 +122,23 @@ final class SkipFFITests: XCTestCase {
     }
 }
 
+
+final class DarwinDirect {
+    init() {
+        #if SKIP
+        // Android JNA error: "java.lang.IllegalStateException: The SecurityManager implementation on this platform is broken; you must explicitly provide the class to register"
+        // com.sun.jna.Native.register("c")
+        com.sun.jna.Native.register((DarwinDirect.self as kotlin.reflect.KClass).java, "c")
+        #endif
+    }
+
+    // @JvmName is needed for test cases, since otherwise it is mangled to 'abs$SkipFFI_debugUnitTest'
+    // SKIP INSERT: @JvmName("abs")
+    // SKIP EXTERN
+    func abs(_ value: Int32) -> Int32 { Darwin.abs(value) }
+}
+
+
 #if SKIP
 
 // MARK: BionicDarwin
@@ -135,6 +157,7 @@ private protocol BionicDarwin : com.sun.jna.Library {
 }
 
 
+
 // MARK: LibXMLLibrary
 
 private func LibXMLLibrary() -> LibXMLLibrary {