Function stringToUTF8Array

mkbitmap/mkbitmap.js:1283–1329

(str, heap, outIdx, maxBytesToWrite)

    }
  
  function stringToUTF8Array(str, heap, outIdx, maxBytesToWrite) {
      assert(typeof str === 'string');
      // Parameter maxBytesToWrite is not optional. Negative values, 0, null,
      // undefined and false each don't write out any bytes.
      if (!(maxBytesToWrite > 0))
        return 0;
  
      var startIdx = outIdx;
      var endIdx = outIdx + maxBytesToWrite - 1; // -1 for string null terminator.
      for (var i = 0; i < str.length; ++i) {
        // Gotcha: charCodeAt returns a 16-bit word that is a UTF-16 encoded code
        // unit, not a Unicode code point of the character! So decode
        // UTF16->UTF32->UTF8.
        // See http://unicode.org/faq/utf_bom.html#utf16-3
        // For UTF8 byte structure, see http://en.wikipedia.org/wiki/UTF-8#Description
        // and https://www.ietf.org/rfc/rfc2279.txt
        // and https://tools.ietf.org/html/rfc3629
        var u = str.charCodeAt(i); // possibly a lead surrogate
        if (u >= 0xD800 && u <= 0xDFFF) {
          var u1 = str.charCodeAt(++i);
          u = 0x10000 + ((u & 0x3FF) << 10) | (u1 & 0x3FF);
        }
        if (u <= 0x7F) {
          if (outIdx >= endIdx) break;
          heap[outIdx++] = u;
        } else if (u <= 0x7FF) {
          if (outIdx + 1 >= endIdx) break;
          heap[outIdx++] = 0xC0 | (u >> 6);
          heap[outIdx++] = 0x80 | (u & 63);
        } else if (u <= 0xFFFF) {
          if (outIdx + 2 >= endIdx) break;
          heap[outIdx++] = 0xE0 | (u >> 12);
          heap[outIdx++] = 0x80 | ((u >> 6) & 63);
          heap[outIdx++] = 0x80 | (u & 63);
        } else {
          if (outIdx + 3 >= endIdx) break;
          if (u > 0x10FFFF) warnOnce('Invalid Unicode code point ' + ptrToString(u) + ' encountered when serializing a JS string to a UTF-8 string in wasm memory! (Valid unicode code points should be in range 0-0x10FFFF).');
          heap[outIdx++] = 0xF0 | (u >> 18);
          heap[outIdx++] = 0x80 | ((u >> 12) & 63);
          heap[outIdx++] = 0x80 | ((u >> 6) & 63);
          heap[outIdx++] = 0x80 | (u & 63);
        }
      }
      // Null-terminate the pointer to the buffer.
      heap[outIdx] = 0;
      return outIdx - startIdx;
    }
  /** @type {function(string, boolean=, number=)} */
  function intArrayFromString(stringy, dontAddNull, length) {
    var len = length > 0 ? length : lengthBytesUTF8(stringy)+1;