mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-24 06:14:01 +08:00
Chris Tate
32061e8ba3
Float16Array is a native typed-array kind with IEEE 754 binary16 storage. Stores round the number to nearest-even in one step from the double, as Node does, including overflow to Infinity, subnormals, -0 and NaN; reads widen exactly. The runtime converts with integer operations, so no target needs half-precision hardware or compiler-rt support. Construction, element reads and writes, ArrayBuffer views, fill, set, subarray, slice, both sort orders, constructor values and checked-dynamic storage work as for the other typed arrays. Math.f16round, DataView.prototype.getFloat16 and setFloat16, and util.types.isFloat16Array compile.
96 lines
3.9 KiB
JavaScript
96 lines
3.9 KiB
JavaScript
// Float16Array from JavaScript: construction from lengths, arrays, typed
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// arrays and ArrayBuffer views; round-to-nearest-even stores with overflow,
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// NaN, -0 and subnormals; fill, set, subarray, slice and both sort orders;
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// DataView getFloat16 and setFloat16 in both byte orders; Math.f16round;
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// util.types and instanceof; structuredClone, assert and Buffer views.
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// Node.js prints the same.
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import { types } from "node:util";
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import assert from "node:assert";
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const show = (label , a ) => console.log(label, a.length, Array.from(a).join(","));
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const a = new Float16Array(6);
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a[0] = 1.5;
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a[1] = 65519;
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a[2] = 65520;
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a[3] = 0.1;
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a[4] = -0;
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a[5] = 5.960464477539063e-8 / 2;
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show("rounding", a);
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const b = new Float16Array([NaN, Infinity, -Infinity, 1e-8, 2049, 2051, 4097, -1e6]);
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show("specials", b);
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console.log(Object.is(a[4], -0), a[6], a.length, a.byteLength, Number.isNaN(b[0]));
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const c = Float16Array.from([3.14159, 2.71828, 1.41421]);
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show("from", c);
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const e = new Float16Array(c);
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e[0] = 100;
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show("copy", e);
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show("source untouched", c);
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const f32 = new Float32Array([1 / 3, 2 / 3]);
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show("from f32", new Float16Array(f32));
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const buf = new ArrayBuffer(8);
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const view = new Float16Array(buf, 2, 2);
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view[0] = 1;
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view[1] = -2;
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console.log("view bytes", Array.from(new Uint8Array(buf)).join(","), new Uint16Array(buf)[1]);
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const g = new Float16Array(5);
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g.fill(0.3);
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show("fill", g);
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g.set([1.1, 2.2], 3);
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show("set", g);
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show("subarray", g.subarray(1, 4));
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show("slice", g.slice(-2));
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const h = new Float16Array([3, -0, 0, NaN, -1, 2.5, -Infinity, 0.1]);
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show("sort", h.slice().sort());
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show("sort desc", h.slice().sort((x, y) => y - x));
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show("toSorted", h.toSorted());
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let sum = 0;
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for (const v of c) sum += v;
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console.log("for-of", sum, h.join("|"), String(c), Object.prototype.toString.call(c));
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const dv = new DataView(new ArrayBuffer(8));
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dv.setFloat16(0, 3.14159);
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dv.setFloat16(2, 3.14159, true);
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dv.setFloat16(4, -65504);
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dv.setFloat16(6, NaN, true);
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console.log("dataview", dv.getFloat16(0), dv.getFloat16(2, true), dv.getFloat16(4), dv.getFloat16(6, true), dv.getUint16(0), dv.getUint16(2));
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try {
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dv.getFloat16(7);
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} catch (err) {
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console.log((err ).name, (err ).message);
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}
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console.log("f16round", Math.f16round(1.337), Math.f16round(65520), Math.f16round(-0), Math.f16round(5e-8), Math.f16round(2 ** -25), Math.f16round(1.0009765625 + 2 ** -12));
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console.log("types", types.isFloat16Array(a), types.isFloat32Array(a), types.isTypedArray(a), a instanceof Float16Array);
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const u = a;
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console.log("unknown", u instanceof Float16Array, u instanceof Float32Array);
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const big = new Float16Array(1000);
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for (let i = 0; i < big.length; i++) big[i] = Math.sin(i) * 1000;
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let acc = 0;
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for (let i = 0; i < big.length; i++) acc += big[i] ;
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console.log("loop", acc, big[999]);
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const f = new Float16Array([1.5, NaN, -0, 65504]);
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const clone = structuredClone(f);
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clone[0] = 2;
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console.log(clone[0], f[0], clone.length);
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assert.deepStrictEqual(new Float16Array([NaN, 1]), new Float16Array([NaN, 1]));
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try {
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assert.deepStrictEqual(new Float16Array([0]), new Float16Array([-0]));
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} catch (e) {
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console.log("deepStrictEqual -0", (e ).name);
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}
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assert.deepEqual(new Float16Array([0]), new Float16Array([-0]));
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const raw = Buffer.from(f.buffer);
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console.log(raw.length, raw.readUInt16LE(0), raw.readUInt16LE(6));
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const fromBuf = new Float16Array(f.buffer, 2, 1);
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console.log(Number.isNaN(fromBuf[0]));
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const list = [f, new Float16Array(2)];
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const m = new Map ([["a", f]]);
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console.log(list.length, m.get("a") [3], list[1] .length);
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const Ctor = Float16Array;
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const x = new Ctor(3);
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x[1] = 0.2;
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console.log(x.length, x[1]);
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const y = new Float16Array([1, 2]);
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const D = y.constructor ;
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const z = new D(2);
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console.log(z.length, z instanceof Float16Array);
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const unknownView = new Float16Array([7]);
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console.log(unknownView instanceof Float16Array);
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