index.js

/**
 * @module linefont
 * Values → linefont string: 0–127 map to chars U+0100–U+017F.
 */

/** Max value a single char can encode (higher codepoints render blank). */
export const MAX = 127

const BASE = 0x0100, CHUNK = 8192

const clamp = v => Math.round(Math.min(Math.max(v || 0, 0), MAX))

/**
 * Char for a single value.
 * @param {number} value 0–127, clamped & rounded
 * @returns {string} char in U+0100–U+017F
 */
export const char = value => String.fromCharCode(BASE + clamp(value))

/**
 * Linefont string for values.
 * @param {...number | ArrayLike<number>} values numbers 0–127, or a single (typed) array of them
 * @returns {string}
 */
export default (...values) => {
  const v = values.length === 1 && typeof values[0] === 'object' && values[0] !== null ? values[0] : values
  let out = ''
  for (let i = 0, n = v.length; i < n; i += CHUNK) {
    const end = Math.min(i + CHUNK, n), codes = new Array(end - i)
    for (let j = i; j < end; j++) codes[j - i] = BASE + clamp(v[j])
    out += String.fromCharCode(...codes)
  }
  return out
}