62 lines
1.6 KiB
PHP
62 lines
1.6 KiB
PHP
<?php
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// Base32Serialiser.php
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// Created: 2022-01-13
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// Updated: 2023-01-01
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namespace Index\Serialisation;
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use Index\IO\Stream;
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/**
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* Provides a Base32 serialiser.
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*/
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class Base32Serialiser extends Serialiser {
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private const CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';
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/**
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* Encodes binary data as a Base32 string.
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*
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* @param mixed $input Input binary data.
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* @return string Base32 string representing the binary data.
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*/
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public function serialise(mixed $input): string {
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$input = (string)$input;
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$length = strlen($input);
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$bin = '';
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$output = '';
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for($i = 0; $i < $length; $i++)
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$bin .= sprintf('%08b', ord($input[$i]));
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$bin = str_split($bin, 5);
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$last = array_pop($bin);
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$bin[] = str_pad((string)$last, 5, '0', STR_PAD_RIGHT);
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foreach($bin as $part)
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$output .= self::CHARS[bindec($part)];
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return $output;
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}
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/**
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* Decodes a Base32 string back to binary data.
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*
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* @param Stream|string $input Input Base32 string.
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* @return string Binary data.
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*/
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public function deserialise(Stream|string $input): mixed {
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$input = (string)$input;
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$length = strlen($input);
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$char = $shift = 0;
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$output = '';
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for($i = 0; $i < $length; $i++) {
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$char <<= 5;
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$char += stripos(self::CHARS, $input[$i]);
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$shift = ($shift + 5) % 8;
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$output .= $shift < 5 ? chr(($char & (0xFF << $shift)) >> $shift) : '';
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}
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return $output;
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}
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}
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