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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 <= 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.without_escaping(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 <= 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.without_escaping(input:read()!)
say(b:decode_text()!)
else:
text := input:read()!
say(Base64.parse(text)!.text)
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