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# Base 64 encoding and decoding
_enc := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".bytes()
_EQUAL_BYTE := Byte(0x3D)
_dec : [Byte] = [
255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 62, 255, 255, 255, 63,
52, 53, 54, 55, 56, 57, 58, 59,
60, 61, 255, 255, 255, 255, 255, 255,
255, 0, 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22,
23, 24, 25, 255, 255, 255, 255, 255,
255, 26, 27, 28, 29, 30, 31, 32,
33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48,
49, 50, 51, 255, 255, 255, 255, 255,
]
lang Base64
func parse(text:Text -> Base64?)
return Base64.from_bytes(text.bytes())
func from_bytes(bytes:[Byte] -> Base64?)
output := &[Byte(0) for _ in bytes.length * 4 / 3 + 4]
src := Int64(1)
dest := Int64(1)
while src + 2 <= Int64(bytes.length)
chunk24 := (
(Int32(bytes[src]) <<< 16) or (Int32(bytes[src+1]) <<< 8) or Int32(bytes[src+2])
)
src += 3
output[dest] = _enc[1 + ((chunk24 >>> 18) and 0b111111)]
output[dest+1] = _enc[1 + ((chunk24 >>> 12) and 0b111111)]
output[dest+2] = _enc[1 + ((chunk24 >>> 6) and 0b111111)]
output[dest+3] = _enc[1 + (chunk24 and 0b111111)]
dest += 4
if src + 1 == bytes.length
chunk16 := (
(Int32(bytes[src]) <<< 8) or Int32(bytes[src+1])
)
output[dest] = _enc[1 + ((chunk16 >>> 10) and 0b11111)]
output[dest+1] = _enc[1 + ((chunk16 >>> 4) and 0b111111)]
output[dest+2] = _enc[1 + ((chunk16 <<< 2)and 0b111111)]
output[dest+3] = _EQUAL_BYTE
else if src == bytes.length
chunk8 := Int32(bytes[src])
output[dest] = _enc[1 + ((chunk8 >>> 2) and 0b111111)]
output[dest+1] = _enc[1 + ((chunk8 <<< 4) and 0b111111)]
output[dest+2] = _EQUAL_BYTE
output[dest+3] = _EQUAL_BYTE
return Base64.from_text(Text.from_bytes(output[]) or return none)
func decode_text(b64:Base64 -> Text?)
return Text.from_bytes(b64.decode_bytes() or return none)
func decode_bytes(b64:Base64 -> [Byte]?)
bytes := b64.text.bytes()
output := &[Byte(0) for _ in bytes.length/4 * 3]
src := Int64(1)
dest := Int64(1)
while src + 3 <= Int64(bytes.length)
chunk24 := (
(Int32(_dec[1+bytes[src]]) <<< 18) or
(Int32(_dec[1+bytes[src+1]]) <<< 12) or
(Int32(_dec[1+bytes[src+2]]) <<< 6) or
Int32(_dec[1+bytes[src+3]])
)
src += 4
output[dest] = Byte((chunk24 >>> 16) and 0xFF)
output[dest+1] = Byte((chunk24 >>> 8) and 0xFF)
output[dest+2] = Byte(chunk24 and 0xFF)
dest += 3
while output[-1] == 0xFF
output[] = output.to(-2)
return output[]
func main(input=(/dev/stdin), decode=no)
if decode
b := Base64.from_text(input.read()!)
say(b.decode_text()!)
else
text := input.read()!
say(Base64.parse(text)!.text)
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