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<?php
/**
* ZSTD compressor using FFI and libzstd
* PoC, only for documentation purpose
*
* Copyright (c) 2019 Remi Collet
* License: CC-BY-SA
* http://creativecommons.org/licenses/by-sa/4.0/
*/
namespace Remi;
class Zstd {
static private $ffi = null;
private static function init() {
if (self::$ffi) {
return;
}
// Try if preloaded
try {
self::$ffi = \FFI::scope("_REMI_ZSTD_");
echo "Using FFI::scope OK\n";
} catch (\FFI\Exception $e) {
// Try direct load
self::$ffi = \FFI::load(__DIR__ . '/preload-zstd.h');
echo "Using FFI::load OK\n";
}
if (!self::$ffi) {
throw new \RuntimeException("FFI parse fails");
}
}
public static function compress(string $src): string {
self::init();
$len = strlen($src);
$max = self::$ffi->ZSTD_compressBound($len);
$comp = str_repeat(' ', $max);
$clen = self::$ffi->ZSTD_compress($comp, $max, $src, $len, 6);
if (self::$ffi->ZSTD_isError($clen)) {
throw new \RuntimeException("Compression fails");
}
return substr($comp, 0, $clen);
}
public static function decompress(string $comp): string {
self::init();
$clen = strlen($comp);
$max = self::$ffi->ZSTD_decompressBound($comp, $clen);
$unco = str_repeat(' ', $max);
$ulen = self::$ffi->ZSTD_decompress($unco, $max, $comp, $clen);
if (self::$ffi->ZSTD_isError($clen)) {
throw new \RuntimeException("Decompression fails");
}
return substr($unco, 0, $ulen);
}
}
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