<?php
/**
* Phpmodbus Copyright (c) 2004, 2010 Jan Krakora, WAGO Kontakttechnik GmbH & Co. KG (http://www.wago.com)
*
* This source file is subject to the "PhpModbus license" that is bundled
* with this package in the file license.txt.
*
* @author Jan Krakora
* @copyright Copyright (c) 2004, 2010 Jan Krakora, WAGO Kontakttechnik GmbH & Co. KG (http://www.wago.com)
* @license PhpModbus license
* @category Phpmodbus
* @package Phpmodbus
* @version $id$
*
*/
/**
* PhpType
*
* The class includes set of methods that convert the received Modbus data
* (array of bytes) to the PHP data type, i.e. signed int, unsigned int and float.
*
* @author Jan Krakora
* @copyright Copyright (c) 2004, 2010 Jan Krakora, WAGO Kontakttechnik GmbH & Co. KG (http://www.wago.com)
* @package Phpmodbus
*
*/
class PhpType {
/**
* bytes2float
*
* The function converts array of 4 bytes to float. The return value
* depends on order of the input bytes (endianning).
*
* @param array $values
* @param bool $endianness
* @return float
*/
public static function bytes2float($values, $endianness = 0) {
$data = array();
$real = 0;
// Set the array to correct form
$data = self::checkData($values);
// Combine bytes
$real = self::combineBytes($data, $endianness);
// Convert the real value to float
return (float) self::real2float($real);
}
/**
* bytes2signedInt
*
* The function converts array of 2 or 4 bytes to signed integer.
* The return value depends on order of the input bytes (endianning).
*
* @param array $values
* @param bool $endianness
* @return int
*/
public static function bytes2signedInt($values, $endianness = 0) {
$data = array();
$int = 0;
// Set the array to correct form
$data = self::checkData($values);
// Combine bytes
$int = self::combineBytes($data, $endianness);
// In the case of signed 2 byte value convert it to 4 byte one
if ((count($values) == 2) && ((0x8000 & $int) > 0)) {
$int = 0xFFFF8000 | $int;
}
// Convert the value
return (int) self::dword2signedInt($int);
}
/**
* bytes2unsignedInt
*
* The function converts array of 2 or 4 bytes to unsigned integer.
* The return value depends on order of the input bytes (endianning).
*
* @param array $values
* @param bool $endianness
* @return int|float
*/
public static function bytes2unsignedInt($values, $endianness = 0) {
$data = array();
$int = 0;
// Set the array to correct form
$data = self::checkData($values);
// Combine bytes
$int = self::combineBytes($data, $endianness);
// Convert the value
return self::dword2unsignedInt($int);
}
/**
* bytes2string
*
* The function converts an values array to the string. The function detects
* the end of the string by 0x00 character as defined by string standards.
*
* @param array $values
* @param bool $endianness
* @return string
*/
public static function bytes2string($values, $endianness = 0) {
// Prepare string variable
$str = "";
// Parse the received data word array
for($i=0;$i<count($values);$i+=2) {
if ($endianness) {
if($values[$i] != 0)
$str .= chr($values[$i]);
else
break;
if($values[$i+1] != 0)
$str .= chr($values[$i+1]);
else
break;
}
else {
if($values[$i+1] != 0)
$str .= chr($values[$i+1]);
else
break;
if($values[$i] != 0)
$str .= chr($values[$i]);
else
break;
}
}
// return string
return $str;
}
/**
* real2float
*
* This function converts a value in IEC-1131 REAL single precision form to float.
*
* For more see [{@link http://en.wikipedia.org/wiki/Single_precision Single precision on Wiki}] or
* [{@link http://de.php.net/manual/en/function.base-convert.php PHP base_convert function commentary}, Todd Stokes @ Georgia Tech 21-Nov-2007] or
* [{@link http://www.php.net/manual/en/function.pack.php PHP pack/unpack functionality}]
*
* @param value value in IEC REAL data type to be converted
* @return float float value
*/
private static function real2float($value) {
// get unsigned long
$ulong = pack("L", $value);
// set float
$float = unpack("f", $ulong);
return $float[1];
}
/**
* dword2signedInt
*
* Switch double word to signed integer
*
* @param int $value
* @return int
*/
private static function dword2signedInt($value) {
if ((0x80000000 & $value) != 0) {
return -(0x7FFFFFFF & ~$value)-1;
} else {
return (0x7FFFFFFF & $value);
}
}
/**
* dword2signedInt
*
* Switch double word to unsigned integer
*
* @param int $value
* @return int|float
*/
private static function dword2unsignedInt($value) {
if ((0x80000000 & $value) != 0) {
return ((float) (0x7FFFFFFF & $value)) + 2147483648;
} else {
return (int) (0x7FFFFFFF & $value);
}
}
/**
* checkData
*
* Check if the data variable is array, and check if the values are numeric
*
* @param int $data
* @return int
*/
private static function checkData($data) {
// Check the data
if (!is_array($data) ||
count($data)<2 ||
count($data)>4 ||
count($data)==3) {
throw new Exception('The input data should be an array of 2 or 4 bytes.');
}
// Fill the rest of array by zeroes
if (count($data) == 2) {
$data[2] = 0;
$data[3] = 0;
}
// Check the values to be number
if (!is_numeric($data[0]) ||
!is_numeric($data[1]) ||
!is_numeric($data[2]) ||
!is_numeric($data[3])) {
throw new Exception('Data are not numeric or the array keys are not indexed by 0,1,2 and 3');
}
return $data;
}
/**
* combineBytes
*
* Combine bytes together
*
* @param int $data
* @param bool $endianness
* @return int
*/
private static function combineBytes($data, $endianness) {
$value = 0;
// Combine bytes
if ($endianness == 0)
$value = (($data[3] & 0xFF)<<16) |
(($data[2] & 0xFF)<<24) |
(($data[1] & 0xFF)) |
(($data[0] & 0xFF)<<8);
else
$value = (($data[3] & 0xFF)<<24) |
(($data[2] & 0xFF)<<16) |
(($data[1] & 0xFF)<<8) |
(($data[0] & 0xFF));
return $value;
}
}
?>