LibJS: Implement Atomics.sub

Userland/Libraries/LibJS/Runtime/AtomicsObject.cpp

@@ -121,6 +121,7 @@ void AtomicsObject::initialize(GlobalObject& global_object)
     define_native_function(vm.names.and_, and_, 3, attr);
     define_native_function(vm.names.load, load, 2, attr);
     define_native_function(vm.names.or_, or_, 3, attr);
+    define_native_function(vm.names.sub, sub, 3, attr);
 
     // 25.4.15 Atomics [ @@toStringTag ], https://tc39.es/ecma262/#sec-atomics-@@tostringtag
     define_direct_property(*vm.well_known_symbol_to_string_tag(), js_string(global_object.heap(), "Atomics"), Attribute::Configurable);
@@ -203,4 +204,22 @@ JS_DEFINE_NATIVE_FUNCTION(AtomicsObject::or_)
     VERIFY_NOT_REACHED();
 }
 
+// 25.4.11 Atomics.sub ( typedArray, index, value ), https://tc39.es/ecma262/#sec-atomics.sub
+JS_DEFINE_NATIVE_FUNCTION(AtomicsObject::sub)
+{
+    auto* typed_array = typed_array_from(global_object, vm.argument(0));
+    if (!typed_array)
+        return {};
+
+    auto atomic_sub = [](auto* storage, auto value) { return AK::atomic_fetch_sub(storage, value); };
+
+#define __JS_ENUMERATE(ClassName, snake_name, PrototypeName, ConstructorName, Type) \
+    if (is<ClassName>(typed_array))                                                 \
+        return perform_atomic_operation<Type>(global_object, *typed_array, move(atomic_sub));
+    JS_ENUMERATE_TYPED_ARRAYS
+#undef __JS_ENUMERATE
+
+    VERIFY_NOT_REACHED();
+}
+
 }

Userland/Libraries/LibJS/Runtime/AtomicsObject.h

@@ -23,6 +23,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(and_);
     JS_DECLARE_NATIVE_FUNCTION(load);
     JS_DECLARE_NATIVE_FUNCTION(or_);
+    JS_DECLARE_NATIVE_FUNCTION(sub);
 };
 
 }

Userland/Libraries/LibJS/Tests/builtins/Atomics/Atomics.sub.js

@@ -0,0 +1,74 @@
+test("invariants", () => {
+    expect(Atomics.sub).toHaveLength(3);
+});
+
+test("error cases", () => {
+    expect(() => {
+        Atomics.sub("not an array", 0, 1);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const bad_array_type = new Float32Array(4);
+        Atomics.sub(bad_array_type, 0, 1);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const bad_array_type = new Uint8ClampedArray(4);
+        Atomics.sub(bad_array_type, 0, 1);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const array = new Int32Array(4);
+        Atomics.sub(array, 100, 1);
+    }).toThrow(RangeError);
+});
+
+test("basic functionality (non-BigInt)", () => {
+    [Int8Array, Int16Array, Int32Array, Uint8Array, Uint16Array, Uint32Array].forEach(ArrayType => {
+        const array = new ArrayType(4);
+        array[0] = 1;
+        array[1] = 2;
+        array[2] = 3;
+        array[3] = 4;
+
+        expect(Atomics.sub(array, 0, 1)).toBe(1);
+        expect(array).toEqual([0, 2, 3, 4]);
+
+        expect(Atomics.sub(array, 1, 1)).toBe(2);
+        expect(array).toEqual([0, 1, 3, 4]);
+
+        expect(Atomics.sub(array, 1, 1)).toBe(1);
+        expect(array).toEqual([0, 0, 3, 4]);
+
+        expect(Atomics.sub(array, 2, 3.14)).toBe(3);
+        expect(array).toEqual([0, 0, 0, 4]);
+
+        expect(Atomics.sub(array, 3, "1")).toBe(4);
+        expect(array).toEqual([0, 0, 0, 3]);
+    });
+});
+
+test("basic functionality (BigInt)", () => {
+    [BigInt64Array, BigUint64Array].forEach(ArrayType => {
+        const array = new ArrayType(4);
+        array[0] = 1n;
+        array[1] = 2n;
+        array[2] = 3n;
+        array[3] = 4n;
+
+        expect(Atomics.sub(array, 0, 1n)).toBe(1n);
+        expect(array).toEqual([0n, 2n, 3n, 4n]);
+
+        expect(Atomics.sub(array, 1, 1n)).toBe(2n);
+        expect(array).toEqual([0n, 1n, 3n, 4n]);
+
+        expect(Atomics.sub(array, 1, 1n)).toBe(1n);
+        expect(array).toEqual([0n, 0n, 3n, 4n]);
+
+        expect(Atomics.sub(array, 2, 3n)).toBe(3n);
+        expect(array).toEqual([0n, 0n, 0n, 4n]);
+
+        expect(Atomics.sub(array, 3, 1n)).toBe(4n);
+        expect(array).toEqual([0n, 0n, 0n, 3n]);
+    });
+});