Function digitToBasic

lib/punycode.js:180–184

(digit, flag)

 * if `flag` is non-zero and `digit` has no uppercase form.
 */
const digitToBasic = function(digit, flag) {
	//  0..25 map to ASCII a..z or A..Z
	// 26..35 map to ASCII 0..9
	return digit + 22 + 75 * (digit < 26) - ((flag != 0) << 5);
};

/**
 * Bias adaptation function as per section 3.4 of RFC 3492.