Add SIMD vector generators for Float16

Sources/PropertyBased/Gen+SIMD.swift

@@ -103,6 +103,35 @@ extension Gen<SIMD4<Double>> {
     }
 }
 
+#if !((os(macOS) || targetEnvironment(macCatalyst)) && arch(x86_64))
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+extension Gen<SIMD2<Float16>> {
+    /// A generator of vectors with length 1.
+    public static var unitVector: Generator<SIMD2<Float16>, Shrink.None<(Float16, Float16)>> {
+        let gen = Gen<Float16>.float16(in: 0...1)
+        return gen.simd2.map { normalize($0) }.filter { $0.x.isFinite }.withoutShrink()
+    }
+}
+
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+extension Gen<SIMD3<Float16>> {
+    /// A generator of vectors with length 1.
+    public static var unitVector: Generator<SIMD3<Float16>, Shrink.None<(Float16, Float16, Float16)>> {
+        let gen = Gen<Float16>.float16(in: 0...1)
+        return gen.simd3.map { normalize($0) }.filter { $0.x.isFinite }.withoutShrink()
+    }
+}
+
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+extension Gen<SIMD4<Float16>> {
+    /// A generator of vectors with length 1.
+    public static var unitVector: Generator<SIMD4<Float16>, Shrink.None<(Float16, Float16, Float16, Float16)>> {
+        let gen = Gen<Float16>.float16(in: 0...1)
+        return gen.simd4.map { normalize($0) }.filter { $0.x.isFinite }.withoutShrink()
+    }
+}
+#endif
+
 #if canImport(simd)
 extension Gen where Value == simd_quatf {
     /// A generator of rotation quaternions with length 1 and a random angle.
@@ -121,6 +150,19 @@ extension Gen where Value == simd_quatd {
         return zip(angle, vector).map { t in simd.simd_quatd(angle: t.0, axis: t.1) }
     }
 }
+
+#if !((os(macOS) || targetEnvironment(macCatalyst)) && arch(x86_64))
+@available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+extension Gen where Value == simd_quath {
+    /// A generator of rotation quaternions with length 1 and a random angle.
+    public static var simd_quath: Generator<simd_quath, Shrink.Tuple<(Float, (Float, Float, Float))>> {
+        return Gen<simd_quatf>.simd_quatf.map { q in
+            simd.simd_quath(vector: simd_half4(q.vector))
+        }
+    }
+}
+#endif
+
 #endif
 
 @_disfavoredOverload

Tests/PropertyBasedTests/GenTests+SIMD.swift

@@ -74,6 +74,21 @@ import simd
         await unitVectorCheck(Gen<SIMD4<Double>>.unitVector)
     }
 
+    #if !((os(macOS) || targetEnvironment(macCatalyst)) && arch(x86_64))
+    @available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+    @Test func testUnitVectorHalf2() async {
+        await unitVectorCheck(Gen<SIMD2<Float16>>.unitVector)
+    }
+    @available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+    @Test func testUnitVectorHalf3() async {
+        await unitVectorCheck(Gen<SIMD3<Float16>>.unitVector)
+    }
+    @available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+    @Test func testUnitVectorHalf4() async {
+        await unitVectorCheck(Gen<SIMD4<Float16>>.unitVector)
+    }
+    #endif
+
     @Test func testVectorLength() {
         #expect(!length([2, 0] as SIMD2<Float>).isApproximately(1))
         #expect(length([3, 0] as SIMD2<Float>).isApproximately(3))
@@ -96,11 +111,23 @@ import simd
             #expect(quat.length.isApproximately(1))
         }
     }
+
+    #if !((os(macOS) || targetEnvironment(macCatalyst)) && arch(x86_64))
+    @available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
+    @Test func testQuatH() async {
+        await testGen(Gen.simd_quath.map(\.vector))
+        await propertyCheck(input: Gen.simd_quath) { quat in
+            let cast = simd_quatf(vector: .init(quat.vector))
+            #expect(cast.length.isApproximately(1))
+        }
+    }
+    #endif
+
     #endif
 }
 
 extension FloatingPoint where Self: ExpressibleByFloatLiteral {
-    func isApproximately(_ other: Self, tolerance: Self = 0.001) -> Bool {
+    func isApproximately(_ other: Self, tolerance: Self = 0.01) -> Bool {
         return abs(self - other) < tolerance
     }
 }