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<?php |
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namespace SPSS; |
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use SPSS\Sav\Record\Variable; |
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class Utils |
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{ |
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/** |
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* SPSS represents a date as the number of seconds since the epoch, midnight, Oct. 14, 1582. |
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* |
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* @param $timestamp |
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* @param string $format |
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* @return false|int |
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*/ |
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public static function formatDate($timestamp, $format = 'Y M d') |
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{ |
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return date($format, strtotime('1582-10-04 00:00:00') + $timestamp); |
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} |
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/** |
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* Rounds X up to the next multiple of Y. |
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* |
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* @param int $x |
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* @param int $y |
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* @return int |
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*/ |
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public static function roundUp($x, $y) |
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{ |
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return ceil($x / $y) * $y; |
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} |
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/** |
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* Rounds X down to the prev multiple of Y. |
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* |
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* @param int $x |
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* @param int $y |
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* @return int |
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*/ |
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public static function roundDown($x, $y) |
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{ |
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return floor($x / $y) * $y; |
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} |
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/** |
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* Convert bytes to string |
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* |
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* @param array $bytes |
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* @return string |
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*/ |
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public static function bytesToString(array $bytes) |
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{ |
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$str = ''; |
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foreach ($bytes as $byte) { |
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$str .= chr($byte); |
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} |
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return $str; |
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} |
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/** |
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* Convert double to string |
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* |
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* @param double $num |
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* @return string |
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*/ |
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public static function doubleToString($num) |
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{ |
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return self::bytesToString(unpack('C8', pack('d', $num))); |
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} |
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/** |
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* @param string $str |
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* @return double |
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*/ |
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public static function stringToDouble($str) |
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{ |
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// if (strlen($str) < 8) { |
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// throw new Exception('String must be a 8 length'); |
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// } |
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return unpack('d', pack('A8', $str))[1]; |
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} |
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/** |
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* @param array $bytes |
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* @param bool $unsigned |
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* @return int |
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*/ |
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public static function bytesToInt(array $bytes, $unsigned = true) |
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{ |
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$bytes = array_reverse($bytes); |
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$value = 0; |
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foreach ($bytes as $i => $b) { |
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$value |= $b << $i * 8; |
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} |
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return $unsigned ? $value : self::unsignedToSigned($value, count($bytes) * 8); |
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} |
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/** |
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* @param $int |
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* @param int $size |
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* @return array |
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*/ |
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public static function intToBytes($int, $size = 32) |
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{ |
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$size = self::roundUp($size, 8); |
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$bytes = []; |
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for ($i = 0; $i < $size; $i += 8) { |
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$bytes[] = 0xFF & $int >> $i; |
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} |
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$bytes = array_reverse($bytes); |
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return $bytes; |
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} |
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/** |
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* @param int $value |
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* @param int $size |
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* @return string |
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*/ |
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public static function unsignedToSigned($value, $size = 32) |
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{ |
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$size = self::roundUp($size, 8); |
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if (bccomp($value, bcpow(2, $size - 1)) >= 0) { |
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$value = bcsub($value, bcpow(2, $size)); |
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} |
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return $value; |
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} |
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/** |
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* @param int $value |
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* @param int $size |
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* @return string |
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*/ |
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public static function signedToUnsigned($value, $size = 32) |
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{ |
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return $value + bcpow(2, $size); |
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} |
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/** |
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* Returns the number of 8-byte units (octs) used to write data for a variable of the given WIDTH. |
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* |
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* @param int $width |
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* @return int |
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*/ |
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public static function widthToOcts($width) |
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{ |
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$result = 0; |
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foreach(self::getSegments($width) as $segmentWidth) { |
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$result += ceil($segmentWidth / 8); |
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} |
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return (int) max(1, $result); |
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} |
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/** |
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* Returns the number of "segments" used for writing case data for a variable of the given WIDTH. |
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* A segment is a physical variable in the system file that represents some piece of a logical variable. |
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* Only very long string variables have more than one segment. |
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* |
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* @param int $width |
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* @return int |
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*/ |
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public static function widthToSegments(int $width): int |
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{ |
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return (int) Variable::isVeryLong($width) ? ceil($width / Variable::EFFECTIVE_VLS_CHUNK) : 1; |
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} |
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public static function getSegments(int $width): iterable |
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{ |
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$count = self::widthToSegments($width); |
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for($i = 1; $i < $count; $i++) { |
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yield 255; |
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} |
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yield $width - ($count - 1) * Variable::EFFECTIVE_VLS_CHUNK; |
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} |
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} |
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