Files
ask262/engine262/src/intrinsics/Math.mts
T

289 lines
8.4 KiB
TypeScript

import { surroundingAgent } from '../host-defined/engine.mts';
import {
Descriptor,
Value,
NumberValue,
type Arguments,
} from '../value.mts';
import { Q, X, type ValueEvaluator } from '../completion.mts';
import { bootstrapPrototype } from './bootstrap.mts';
import {
CreateBuiltinFunction,
ToNumber,
F, R,
Realm,
RequireObjectCoercible,
GetIterator,
IteratorStepValue,
IteratorClose,
} from '#self';
/** https://tc39.es/ecma262/#sec-math.abs */
function* Math_abs([x = Value.undefined]: Arguments): ValueEvaluator {
const n = Q(yield* ToNumber(x));
if (n.isNaN()) {
return n;
} else if (Object.is(R(n), -0)) {
return F(+0);
} else if (n.isInfinity()) {
return F(Infinity);
}
if (R(n) < 0) {
return F(-R(n));
}
return n;
}
/** https://tc39.es/ecma262/#sec-math.acos */
function* Math_acos([x = Value.undefined]: Arguments): ValueEvaluator {
const n = Q(yield* ToNumber(x));
if (n.isNaN()) {
return n;
} else if (R(n) > 1) {
return F(NaN);
} else if (R(n) < -1) {
return F(NaN);
} else if (R(n) === 1) {
return F(+0);
}
return F(Math.acos(R(n)));
}
/** https://tc39.es/ecma262/#sec-math.pow */
function* Math_pow([base = Value.undefined, exponent = Value.undefined]: Arguments): ValueEvaluator {
// 1. Set base to ? ToNumber(base).
base = Q(yield* ToNumber(base));
// 2. Set exponent to ? ToNumber(exponent).
exponent = Q(yield* ToNumber(exponent));
// 3. Return ! Number::exponentiate(base, exponent).
return X(NumberValue.exponentiate(base, exponent));
}
/** @param {bigint} h */
function fmix64(h: bigint) {
h ^= h >> 33n;
h *= 0xFF51AFD7ED558CCDn;
h ^= h >> 33n;
h *= 0xC4CEB9FE1A85EC53n;
h ^= h >> 33n;
return h;
}
const floatView = new Float64Array(1);
const big64View = new BigUint64Array(floatView.buffer);
/** https://tc39.es/ecma262/#sec-math.random */
function Math_random() {
const realm = surroundingAgent.currentRealmRecord;
if (realm.randomState === undefined) {
const seed = realm.HostDefined.randomSeed
? BigInt(X(realm.HostDefined.randomSeed()))
: BigInt(Math.round(Math.random() * (2 ** 32)));
realm.randomState = new BigUint64Array([
fmix64(BigInt.asUintN(64, seed)),
fmix64(BigInt.asUintN(64, ~seed)),
]);
}
const s = realm.randomState;
// XorShift128+
let s1 = s[0];
const s0 = s[1];
s[0] = s0;
s1 ^= s1 << 23n;
s1 ^= s1 >> 17n;
s1 ^= s0;
s1 ^= s0 >> 26n;
s[1] = s1;
// Convert to double in [0, 1) range
big64View[0] = (s0 >> 12n) | 0x3FF0000000000000n;
const result = floatView[0] - 1;
return F(result);
}
/** https://tc39.es/ecma262/#sec-math.sumprecise */
function* Math_sumPrecise([items = Value.undefined]: Arguments): ValueEvaluator {
Q(RequireObjectCoercible(items));
const iteratorRecord = Q(yield* GetIterator(items, 'sync'));
let state: 'minus-zero' | 'not-a-number' | 'minus-infinity' | 'plus-infinity' | 'finite' = 'minus-zero';
const sums: number[] = [];
let count = 0;
let next: 'not-started' | 'done' | Value = 'not-started';
while (next !== 'done') {
next = Q(yield* IteratorStepValue(iteratorRecord));
if (next !== 'done') {
if (count >= 2 ** 53 - 1) {
const error = surroundingAgent.Throw('RangeError', 'OutOfRange', '');
return Q(yield* IteratorClose(iteratorRecord, error));
}
if (!(next instanceof NumberValue)) {
const error = surroundingAgent.Throw('TypeError', 'NotANumber', next);
return Q(yield* IteratorClose(iteratorRecord, error));
}
const n = R(next);
if (state !== 'not-a-number') {
if (Number.isNaN(n)) {
state = 'not-a-number';
} else if (n === Infinity) {
if (state === 'minus-infinity') {
state = 'not-a-number';
} else {
state = 'plus-infinity';
}
} else if (n === -Infinity) {
if (state === 'plus-infinity') {
state = 'not-a-number';
} else {
state = 'minus-infinity';
}
} else if (!Object.is(n, -0) && (state === 'minus-zero' || state === 'finite')) {
state = 'finite';
sums.push(n);
}
}
count += 1;
}
}
if (state === 'not-a-number') {
return F(NaN);
}
if (state === 'plus-infinity') {
return F(Infinity);
}
if (state === 'minus-infinity') {
return F(-Infinity);
}
if (state === 'minus-zero') {
return F(-0);
}
return F(sum(sums));
function sum(items: number[]) {
if ('sumPrecise' in Math) {
// @ts-expect-error
return Math.sumPrecise(items);
}
const fractional_parts: number[] = [];
let whole_part_sum = 0n;
items.forEach((n) => {
const whole_num = Math.trunc(n);
fractional_parts.push(n - whole_num);
whole_part_sum += BigInt(whole_num);
});
const fractional_parts_as_hex = fractional_parts.map((n) => n.toString(32));
const fractional: number[] = [];
for (const fractional_str of fractional_parts_as_hex) {
const neg = fractional_str[0] === '-';
const prefix = neg ? 3 : 2; // -0.xxx or 0.xxx
for (let index = prefix; index < fractional_str.length; index += 1) {
fractional[index - prefix] ??= 0;
if (neg) {
fractional[index - prefix] -= parseInt(fractional_str[index], 32);
} else {
fractional[index - prefix] += parseInt(fractional_str[index], 32);
}
}
}
for (let index = fractional.length - 1; index >= 0; index -= 1) {
const element = fractional[index];
if (element >= 32) {
fractional[index] = element % 32;
fractional[index - 1] ??= 0;
fractional[index - 1] += Math.floor(element / 32);
}
if (element < 0) {
fractional[index] = 32 + element;
fractional[index - 1] ??= 0;
fractional[index - 1] -= 1;
}
}
const fractional_part = fractional.reduceRight((acc, digit, index) => acc + digit * 32 ** -(index + 1), 0);
if (fractional[-1]) {
whole_part_sum += BigInt(fractional[-1]);
}
return Number(whole_part_sum) + fractional_part;
}
}
/** https://tc39.es/ecma262/#sec-math-object */
export function bootstrapMath(realmRec: Realm) {
/** https://tc39.es/ecma262/#sec-value-properties-of-the-math-object */
const readonly = { Writable: Value.false, Configurable: Value.false };
// @@toStringTag is handled in the bootstrapPrototype() call.
const mathObj = bootstrapPrototype(realmRec, [
['E', F(2.718281828459045), undefined, readonly],
['LN10', F(2.302585092994046), undefined, readonly],
['LN2', F(0.6931471805599453), undefined, readonly],
['LOG10E', F(0.4342944819032518), undefined, readonly],
['LOG2E', F(1.4426950408889634), undefined, readonly],
['PI', F(3.141592653589793), undefined, readonly],
['SQRT1_2', F(0.7071067811865476), undefined, readonly],
['SQRT2', F(1.4142135623730951), undefined, readonly],
['abs', Math_abs, 1],
['acos', Math_acos, 1],
['pow', Math_pow, 2],
['random', Math_random, 0],
['sumPrecise', Math_sumPrecise, 1],
], realmRec.Intrinsics['%Object.prototype%'], 'Math');
/** https://tc39.es/ecma262/#sec-function-properties-of-the-math-object */
([
['acosh', 1],
['asin', 1],
['asinh', 1],
['atan', 1],
['atanh', 1],
['atan2', 2],
['cbrt', 1],
['ceil', 1],
['clz32', 1],
['cos', 1],
['cosh', 1],
['exp', 1],
['expm1', 1],
['floor', 1],
['fround', 1],
['hypot', 2],
['imul', 2],
['log', 1],
['log1p', 1],
['log10', 1],
['log2', 1],
['max', 2],
['min', 2],
['round', 1],
['sign', 1],
['sin', 1],
['sinh', 1],
['sqrt', 1],
['tan', 1],
['tanh', 1],
['trunc', 1],
] as const).forEach(([name, length]) => {
// TODO(18): Math
/** https://tc39.es/ecma262/#sec-function-properties-of-the-math-object */
const method = function* method(args: Arguments): ValueEvaluator {
const nextArgs: number[] = [];
for (let i = 0; i < args.length; i += 1) {
nextArgs[i] = R(Q(yield* ToNumber(args[i]!)));
}
// we're calling host Math functions here.
return F((Math[name] as (...args: unknown[]) => number)(...nextArgs));
};
const func = CreateBuiltinFunction(method, length, Value(name), [], realmRec);
X(mathObj.DefineOwnProperty(Value(name), Descriptor({
Value: func,
Writable: Value.true,
Enumerable: Value.false,
Configurable: Value.true,
})));
});
realmRec.Intrinsics['%Math%'] = mathObj;
}