base64.go

package bits

// Configure the bit writing and reading functions to work natively in BASE-64
// encoding. That way, we don't have to convert back and forth to bytes.

var BASE64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"

/**
  The width of each unit of the encoding, in bits. Here we use 6, for base-64
  encoding.
*/
var W uint = 6

/**
  Returns the character unit that represents the given value. If this were
  binary data, we would simply return id.
*/
func CHR(id uint) string {
	return BASE64[id : id+1]
}

/**
  Returns the decimal value of the given character unit.
*/
var BASE64_CACHE = map[string]uint{
	"A": 0, "B": 1, "C": 2, "D": 3, "E": 4, "F": 5, "G": 6, "H": 7,
	"I": 8, "J": 9, "K": 10, "L": 11, "M": 12, "N": 13, "O": 14,
	"P": 15, "Q": 16, "R": 17, "S": 18, "T": 19, "U": 20, "V": 21,
	"W": 22, "X": 23, "Y": 24, "Z": 25, "a": 26, "b": 27, "c": 28,
	"d": 29, "e": 30, "f": 31, "g": 32, "h": 33, "i": 34, "j": 35,
	"k": 36, "l": 37, "m": 38, "n": 39, "o": 40, "p": 41, "q": 42,
	"r": 43, "s": 44, "t": 45, "u": 46, "v": 47, "w": 48, "x": 49,
	"y": 50, "z": 51, "0": 52, "1": 53, "2": 54, "3": 55, "4": 56,
	"5": 57, "6": 58, "7": 59, "8": 60, "9": 61, "-": 62, "_": 63,
}

func ORD(ch string) uint {
	// Used to be: return BASE64.indexOf(ch);
	return BASE64_CACHE[ch]
}