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<?php

/**

 * Pure-PHP 32-bit BigInteger Engine

 *

 * PHP version 5 and 7

 *

 * @category  Math

 * @package   BigInteger

 * @author    Jim Wigginton <terrafrost@php.net>

 * @copyright 2017 Jim Wigginton

 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License

 * @link      http://pear.php.net/package/Math_BigInteger

 */

namespace phpseclib3\Math\BigInteger\Engines;

/**

 * Pure-PHP 32-bit Engine.

 *

 * Uses 64-bit floats if int size is 4 bits

 *

 * @package PHP32

 * @author  Jim Wigginton <terrafrost@php.net>

 * @access  public

 */

class PHP32 extends PHP

{

    // Constants used by PHP.php

    const BASE = 26;

    const BASE_FULL = 0x4000000;

    const MAX_DIGIT = 0x3FFFFFF;

    const MSB = 0x2000000;

    /**

     * MAX10 in greatest MAX10LEN satisfying

     * MAX10 = 10**MAX10LEN <= 2**BASE.

     */

    const MAX10 = 10000000;

    /**

     * MAX10LEN in greatest MAX10LEN satisfying

     * MAX10 = 10**MAX10LEN <= 2**BASE.

     */

    const MAX10LEN = 7;

    const MAX_DIGIT2 = 4503599627370496;

    /**

     * Initialize a PHP32 BigInteger Engine instance

     *

     * @param int $base

     * @see parent::initialize()

     */

    protected function initialize($base)

    {

        if ($base != 256 && $base != -256) {

            return parent::initialize($base);

        }

        $val = $this->value;

        $this->value = [];

        $vals = &$this->value;

        $i = strlen($val);

        if (!$i) {

            return;

        }

        while (true) {

            $i -= 4;

            if ($i < 0) {

                if ($i == -4) {

                    break;

                }

                $val = substr($val, 0, 4 + $i);

                $val = str_pad($val, 4, "\0", STR_PAD_LEFT);

                if ($val == "\0\0\0\0") {

                    break;

                }

                $i = 0;

            }

            list(, $digit) = unpack('N', substr($val, $i, 4));

            $step = count($vals) & 3;

            if ($step) {

                $digit >>= 2 * $step;

            }

            if ($step != 3) {

                $digit &= static::MAX_DIGIT;

                $i++;

            }

            $vals[] = $digit;

        }

        while (end($vals) === 0) {

            array_pop($vals);

        }

        reset($vals);

    }

    /**

     * Test for engine validity

     *

     * @see parent::__construct()

     * @return bool

     */

    public static function isValidEngine()

    {

        return PHP_INT_SIZE >= 4;

    }

    /**

     * Adds two BigIntegers.

     *

     * @param PHP32 $y

     * @return PHP32

     */

    public function add(PHP32 $y)

    {

        $temp = self::addHelper($this->value, $this->is_negative, $y->value, $y->is_negative);

        return $this->convertToObj($temp);

    }

    /**

     * Subtracts two BigIntegers.

     *

     * @param PHP32 $y

     * @return PHP32

     */

    public function subtract(PHP32 $y)

    {

        $temp = self::subtractHelper($this->value, $this->is_negative, $y->value, $y->is_negative);

        return $this->convertToObj($temp);

    }

    /**

     * Multiplies two BigIntegers.

     *

     * @param PHP32 $y

     * @return PHP32

     */

    public function multiply(PHP32 $y)

    {

        $temp = self::multiplyHelper($this->value, $this->is_negative, $y->value, $y->is_negative);

        return $this->convertToObj($temp);

    }

    /**

     * Divides two BigIntegers.

     *

     * Returns an array whose first element contains the quotient and whose second element contains the

     * "common residue".  If the remainder would be positive, the "common residue" and the remainder are the

     * same.  If the remainder would be negative, the "common residue" is equal to the sum of the remainder

     * and the divisor (basically, the "common residue" is the first positive modulo).

     *

     * @param PHP32 $y

     * @return array{PHP32, PHP32}

     */

    public function divide(PHP32 $y)

    {

        return $this->divideHelper($y);

    }

    /**

     * Calculates modular inverses.

     *

     * Say you have (30 mod 17 * x mod 17) mod 17 == 1.  x can be found using modular inverses.

     * @param PHP32 $n

     * @return false|PHP32

     */

    public function modInverse(PHP32 $n)

    {

        return $this->modInverseHelper($n);

    }

    /**

     * Calculates modular inverses.

     *

     * Say you have (30 mod 17 * x mod 17) mod 17 == 1.  x can be found using modular inverses.

     * @param PHP32 $n

     * @return PHP32[]

     */

    public function extendedGCD(PHP32 $n)

    {

        return $this->extendedGCDHelper($n);

    }

    /**

     * Calculates the greatest common divisor

     *

     * Say you have 693 and 609.  The GCD is 21.

     *

     * @param PHP32 $n

     * @return PHP32

     */

    public function gcd(PHP32 $n)

    {

        return $this->extendedGCD($n)['gcd'];

    }

    /**

     * Logical And

     *

     * @param PHP32 $x

     * @return PHP32

     */

    public function bitwise_and(PHP32 $x)

    {

        return $this->bitwiseAndHelper($x);

    }

    /**

     * Logical Or

     *

     * @param PHP32 $x

     * @return PHP32

     */

    public function bitwise_or(PHP32 $x)

    {

        return $this->bitwiseOrHelper($x);

    }

    /**

     * Logical Exclusive Or

     *

     * @param PHP32 $x

     * @return PHP32

     */

    public function bitwise_xor(PHP32 $x)

    {

        return $this->bitwiseXorHelper($x);

    }

    /**

     * Compares two numbers.

     *

     * Although one might think !$x->compare($y) means $x != $y, it, in fact, means the opposite.  The reason for this is

     * demonstrated thusly:

     *

     * $x  > $y: $x->compare($y)  > 0

     * $x  < $y: $x->compare($y)  < 0

     * $x == $y: $x->compare($y) == 0

     *

     * Note how the same comparison operator is used.  If you want to test for equality, use $x->equals($y).

     *

     * {@internal Could return $this->subtract($x), but that's not as fast as what we do do.}

     *

     * @param PHP32 $y

     * @return int in case < 0 if $this is less than $y; > 0 if $this is greater than $y, and 0 if they are equal.

     * @access public

     * @see self::equals()

     */

    public function compare(PHP32 $y)

    {

        return $this->compareHelper($this->value, $this->is_negative, $y->value, $y->is_negative);

    }

    /**

     * Tests the equality of two numbers.

     *

     * If you need to see if one number is greater than or less than another number, use BigInteger::compare()

     *

     * @param PHP32 $x

     * @return bool

     */

    public function equals(PHP32 $x)

    {

        return $this->value === $x->value && $this->is_negative == $x->is_negative;

    }

    /**

     * Performs modular exponentiation.

     *

     * @param PHP32 $e

     * @param PHP32 $n

     * @return PHP32

     */

    public function modPow(PHP32 $e, PHP32 $n)

    {

        return $this->powModOuter($e, $n);

    }

    /**

     * Performs modular exponentiation.

     *

     * Alias for modPow().

     *

     * @param PHP32 $e

     * @param PHP32 $n

     * @return PHP32

     */

    public function powMod(PHP32 $e, PHP32 $n)

    {

        return $this->powModOuter($e, $n);

    }

    /**

     * Generate a random prime number between a range

     *

     * If there's not a prime within the given range, false will be returned.

     *

     * @param PHP32 $min

     * @param PHP32 $max

     * @return false|PHP32

     */

    public static function randomRangePrime(PHP32 $min, PHP32 $max)

    {

        return self::randomRangePrimeOuter($min, $max);

    }

    /**

     * Generate a random number between a range

     *

     * Returns a random number between $min and $max where $min and $max

     * can be defined using one of the two methods:

     *

     * BigInteger::randomRange($min, $max)

     * BigInteger::randomRange($max, $min)

     *

     * @param PHP32 $min

     * @param PHP32 $max

     * @return PHP32

     */

    public static function randomRange(PHP32 $min, PHP32 $max)

    {

        return self::randomRangeHelper($min, $max);

    }

    /**

     * Performs exponentiation.

     *

     * @param PHP32 $n

     * @return PHP32

     */

    public function pow(PHP32 $n)

    {

        return $this->powHelper($n);

    }

    /**

     * Return the minimum BigInteger between an arbitrary number of BigIntegers.

     *

     * @param PHP32 ...$nums

     * @return PHP32

     */

    public static function min(PHP32 ...$nums)

    {

        return self::minHelper($nums);

    }

    /**

     * Return the maximum BigInteger between an arbitrary number of BigIntegers.

     *

     * @param PHP32 ...$nums

     * @return PHP32

     */

    public static function max(PHP32 ...$nums)

    {

        return self::maxHelper($nums);

    }

    /**

     * Tests BigInteger to see if it is between two integers, inclusive

     *

     * @param PHP32 $min

     * @param PHP32 $max

     * @return bool

     */

    public function between(PHP32 $min, PHP32 $max)

    {

        return $this->compare($min) >= 0 && $this->compare($max) <= 0;

    }

}