sidef-scripts/Encoding/integers_binary_encoding.sf at master · trizen/sidef-scripts · GitHub

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#!/usr/bin/ruby

# Author: Trizen

# Date: 23 March 2023

# https://github.com/trizen

# Encode and decode a random list of integers into a binary string.

func encode_integers (Array integers) {

var counts = []

var count = 0

var bits_per_symbol = 2

var processed_len = 0

for k in (integers) {

while (k >= bits_per_symbol) {

if (count > 0) {

counts << [bits_per_symbol.len(2)-1, count]

processed_len += count

}

count = 0

bits_per_symbol *= 2

}

++count

}

counts << [[bits_per_symbol.len(2)-1, integers.len - processed_len]].grep { .tail > 0 }...

var clen = counts.len

var header = clen.chr

for b,len in (counts) {

header += chr(b)

header += pack('N', len)

}

var bits = []

for b,len in (counts) {

bits << integers.splice(0, len).map{ sprintf('%0*s', b, .as_bin) }...

}

header + pack('B*', bits.join)

}

func decode_integers (String str) {

var str_fh = str.open_r(:raw)

var count_len = str_fh.getc.ord

var counts = []

count_len.times {

var b = str_fh.getc.ord

var l = Num(unpack('N', 4.of { str_fh.getc }.join))

counts << [b, l] if (l > 0)

}

var chunks = []

var bits_fh = str_fh.slurp.ascii2bin.open_r(:raw)

for b,len in (counts) {

bits_fh.read(\var chunk, len*b)

chunks << chunk.slices(b)...

}

chunks.map { Num(_, 2) }

}

var integers = 1000.of { .irand }

var str = encode_integers(integers.clone)

say ("Encoded length: ", str.len)

say ("Rawdata length: ", integers.join(' ').len)

var decoded = decode_integers(str)

assert_eq(integers, decoded)

__END__

Encoded length: 1158

Rawdata length: 3621

sidef-scripts/Encoding/integers_binary_encoding.sf at master · trizen/sidef-scripts · GitHub

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