std/io/slice_long_to_bytes.ts

// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.

/**
 * Slice number into 64bit big endian byte array.
 *
 * @example Usage
 * ```ts
 * import { sliceLongToBytes } from "@std/io/slice-long-to-bytes";
 * import { assertEquals } from "@std/assert/equals";
 *
 * const dest = sliceLongToBytes(0x123456789a);
 * assertEquals(dest, [0, 0, 0, 0x12, 0x34, 0x56, 0x78, 0x9a]);
 * ```
 *
 * @param d The number to be sliced
 * @param dest The array to store the sliced bytes
 * @returns The sliced bytes
 *
 * @deprecated This will be removed in the future.
 */
export function sliceLongToBytes(
  d: number,
  dest: number[] = Array.from<number>({ length: 8 }),
): number[] {
  let big = BigInt(d);
  for (let i = 0; i < 8; i++) {
    dest[7 - i] = Number(big & 0xffn);
    big >>= 8n;
  }
  return dest;
}