Conversion fails in some cases about float16

[zqianem]

I did a git bisect and it looks like the culprit is 92e5f2c.

Another case:

#!/bin/env -S deno run

import { assertEquals } from "https://deno.land/[email protected]/assert/mod.ts";
import { f16round } from "https://deno.land/x/[email protected]/mod.ts";

assertEquals(f16round(7.9999999), 8); // => 4

[petamoriken]

I have found a way to fix this bug. It is expected to be fixed by tomorrow.

[bbbbx]

Just a quick test, numbers starting with 0.4999 will be converted to 0.25 (0x3400)

const array = new Float16Array(1000);
for (let i = 0; i < 1000; i++) {
  const dValue = 0.4999 + i * 0.0000001;
  array[i] = dValue;
  console.log(dValue, 'to', array[i]);
  if (array[i] !== 0.25) debugger
}
console.log(array.buffer);

There are more accurate numbers:

• 0x3800 => 0.5
• 0x37ff => 0.499755859375