Method performDecode

src/Encoder/BaudotCode.js:221–256

* Performs decode on given content. * @protected * @param {Chain} content * @return {number[]|string|Uint8Array|Chain|Promise} Decoded content

(content)

   * @return {number[]|string|Uint8Array|Chain|Promise} Decoded content
   */
  performDecode (content) {
    // Retrieve character set
    const variant = this.getSettingValue('variant')
    const characterSet = this.getVariantCharacterSet(variant)
    const switchToFigures = characterSet.indexOf('FS') % 32
    const switchToLetters = characterSet.indexOf('LS') % 32

    // Compose 5-bit tape from byte array
    const tape = ArrayUtil.resizeBitSizedArray(content.getBytes(), 8, 5, true)
    const result = new Array(tape.length)

    // Go through tape and map each character to Unicode code points
    let char, codePoint
    let figureSet = false
    let j = 0

    for (let i = 0; i < tape.length; i++) {
      char = tape[i]

      if (!figureSet && char === switchToFigures) {
        // Switch to figure set
        figureSet = true
      } else if (figureSet && char === switchToLetters) {
        // Switch to letter set
        figureSet = false
      } else {
        // Map tape character
        codePoint = characterSet[char + (figureSet ? 32 : 0)]
        if (codePoint !== null) {
          result[j++] = codePoint
        }
      }
    }

    return result.slice(0, j)
  }

  /**
   * Composes the character set for the given variant name.