98 lines
3.4 KiB
Tcl
98 lines
3.4 KiB
Tcl
# Base 64 encoding and decoding
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_enc := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/":bytes()
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_EQUAL_BYTE := Byte(0x3D)
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_dec := [
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:Byte
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255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 62, 255, 255, 255, 63,
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52, 53, 54, 55, 56, 57, 58, 59,
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60, 61, 255, 255, 255, 255, 255, 255,
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255, 0, 1, 2, 3, 4, 5, 6,
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7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22,
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23, 24, 25, 255, 255, 255, 255, 255,
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255, 26, 27, 28, 29, 30, 31, 32,
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33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48,
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49, 50, 51, 255, 255, 255, 255, 255,
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]
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lang Base64:
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func parse(text:Text -> Base64?):
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return Base64.from_bytes(text:bytes())
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func from_bytes(bytes:[Byte] -> Base64?):
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output := [Byte(0) for _ in bytes.length * 4 / 3 + 4]
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src := Int64(1)
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dest := Int64(1)
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while src + 2 <= bytes.length:
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chunk24 := (
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(Int32(bytes[src]) <<< 16) or (Int32(bytes[src+1]) <<< 8) or Int32(bytes[src+2])
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)
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src += 3
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output[dest] = _enc[1 + ((chunk24 >>> 18) and 0b111111)]
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output[dest+1] = _enc[1 + ((chunk24 >>> 12) and 0b111111)]
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output[dest+2] = _enc[1 + ((chunk24 >>> 6) and 0b111111)]
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output[dest+3] = _enc[1 + (chunk24 and 0b111111)]
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dest += 4
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if src + 1 == bytes.length:
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chunk16 := (
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(Int32(bytes[src]) <<< 8) or Int32(bytes[src+1])
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)
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output[dest] = _enc[1 + ((chunk16 >>> 10) and 0b11111)]
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output[dest+1] = _enc[1 + ((chunk16 >>> 4) and 0b111111)]
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output[dest+2] = _enc[1 + ((chunk16 <<< 2)and 0b111111)]
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output[dest+3] = _EQUAL_BYTE
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else if src == bytes.length:
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chunk8 := Int32(bytes[src])
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output[dest] = _enc[1 + ((chunk8 >>> 2) and 0b111111)]
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output[dest+1] = _enc[1 + ((chunk8 <<< 4) and 0b111111)]
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output[dest+2] = _EQUAL_BYTE
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output[dest+3] = _EQUAL_BYTE
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return Base64.without_escaping(Text.from_bytes(output) or return !Base64)
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func decode_text(b64:Base64 -> Text?):
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return Text.from_bytes(b64:decode_bytes() or return !Text)
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func decode_bytes(b64:Base64 -> [Byte]?):
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bytes := b64.text_content:bytes()
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output := [Byte(0) for _ in bytes.length/4 * 3]
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src := Int64(1)
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dest := Int64(1)
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while src + 3 <= bytes.length:
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chunk24 := (
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(Int32(_dec[1+bytes[src]]) <<< 18) or
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(Int32(_dec[1+bytes[src+1]]) <<< 12) or
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(Int32(_dec[1+bytes[src+2]]) <<< 6) or
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Int32(_dec[1+bytes[src+3]])
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)
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src += 4
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output[dest] = Byte((chunk24 >>> 16) and 0xFF)
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output[dest+1] = Byte((chunk24 >>> 8) and 0xFF)
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output[dest+2] = Byte(chunk24 and 0xFF)
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dest += 3
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while output[-1] == 0xFF:
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output = output:to(-2)
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return output
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func main(input=(/dev/stdin), decode=no):
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if decode:
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b := Base64.without_escaping(input:read()!)
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say(b:decode_text()!)
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else:
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text := input:read()!
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say(Base64.parse(text)!.text_content)
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