mirror of https://github.com/pixelfed/pixelfed.git
39 lines
1.3 KiB
PHP
39 lines
1.3 KiB
PHP
<?php
|
|
|
|
namespace App\Util\Blurhash;
|
|
|
|
use InvalidArgumentException;
|
|
|
|
class Base83 {
|
|
private const ALPHABET = [
|
|
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D',
|
|
'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R',
|
|
'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
|
|
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
|
|
'u', 'v', 'w', 'x', 'y', 'z', '#', '$', '%', '*', '+', ',', '-', '.',
|
|
':', ';', '=', '?', '@', '[', ']', '^', '_', '{', '|', '}', '~'
|
|
];
|
|
|
|
private const BASE = 83;
|
|
|
|
public static function encode(int $value, int $length): string {
|
|
if (floor($value / (self::BASE ** $length)) != 0) {
|
|
throw new InvalidArgumentException('Specified length is too short to encode given value.');
|
|
}
|
|
|
|
$result = '';
|
|
for ($i = 1; $i <= $length; $i++) {
|
|
$digit = floor($value / (self::BASE ** ($length - $i))) % self::BASE;
|
|
$result .= self::ALPHABET[$digit];
|
|
}
|
|
return $result;
|
|
}
|
|
|
|
public static function decode(string $hash): int {
|
|
$result = 0;
|
|
foreach (str_split($hash) as $char) {
|
|
$result = $result * self::BASE + (int) array_search($char, self::ALPHABET, true);
|
|
}
|
|
return (int) $result;
|
|
}
|
|
} |