RosettaCodeData/Task/Variable-length-quantity/Wren/variable-length-quantity.wren

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import "./fmt" for Fmt, Conv
import "./str" for Str
var toOctets = Fn.new { |n|
var s = Conv.itoa(n, 2)
var le = s.count
var r = le % 7
var d = (le/7).floor
if (r > 0) {
d = d + 1
s = Fmt.zfill(7 * d, s)
}
var chunks = Str.chunks(s, 7)
var last = "0" + chunks[-1]
s = chunks[0..-2].map { |ch| "1" + ch }.join() + last
return Str.chunks(s, 8).map { |ch| Conv.atoi(ch, 2) }.toList
}
var fromOctets = Fn.new { |octets|
var s = ""
for (oct in octets) {
var bin = Conv.itoa(oct, 2)
bin = Fmt.zfill(7, bin)
s = s + bin[-7..-1]
}
return Conv.atoi(s, 2)
}
var tests = [2097152, 2097151]
for (test in tests) {
var octets = toOctets.call(test)
var display = octets.map { |oct| "Ox" + Fmt.xz(2, oct) }.toList
System.write("%(test) -> %(Fmt.v("s", 4, display, 0, " ", "")) -> ")
System.print(fromOctets.call(octets))
}