39 lines
1 KiB
Text
39 lines
1 KiB
Text
import "./fmt" for Fmt
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var digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
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var encodeNegBase = Fn.new { |n, b|
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if (b < -62 || b > -1) Fiber.abort("Base must be between -1 and -62")
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if (n == 0) return "0"
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var out = ""
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while (n != 0) {
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var rem = n % b
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n = (n/b).truncate
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if (rem < 0) {
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n = n + 1
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rem = rem -b
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}
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out = out + digits[rem]
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}
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return out[-1..0]
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}
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var decodeNegBase = Fn.new { |ns, b|
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if (b < -62 || b > -1) Fiber.abort("Base must be between -1 and -62")
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if (ns == "0") return 0
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var total = 0
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var bb = 1
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for (c in ns[-1..0]) {
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total = total + digits.indexOf(c)*bb
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bb = bb * b
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}
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return total
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}
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var nbl = [ [10, -2], [146, -3], [15, -10], [-7425195, -62] ]
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for (p in nbl) {
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var ns = encodeNegBase.call(p[0], p[1])
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Fmt.print("$8d encoded in base $-3d = $s", p[0], p[1], ns)
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var n = decodeNegBase.call(ns, p[1])
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Fmt.print("$8s decoded in base $-3d = $d\n", ns, p[1], n)
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}
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