function BigInteger::fromBytes

Translates a string of bytes containing the binary representation of a BigInteger into a BigInteger.

The input string is assumed to be in big-endian byte-order: the most significant byte is in the zeroth element.

If `$signed` is true, the input is assumed to be in two's-complement representation, and the leading bit is interpreted as a sign bit. If `$signed` is false, the input is interpreted as an unsigned number, and the resulting BigInteger will always be positive or zero.

This method can be used to retrieve a number exported by `toBytes()`, as long as the `$signed` flags match.

Parameters

string $value The byte string.:

bool $signed Whether to interpret as a signed number in two's-complement representation with a leading: sign bit.

Throws

NumberFormatException If the string is empty.

1 call to BigInteger::fromBytes()

BigInteger::randomBits in vendor/brick/math/src/BigInteger.php

Generates a pseudo-random number in the range 0 to 2^numBits - 1.

File

vendor/brick/math/src/BigInteger.php, line 174

Class

BigInteger

An arbitrary-size integer.

Namespace

Brick\Math

Code

public static function fromBytes(string $value, bool $signed = true) : BigInteger {
    if ($value === '') {
        throw new NumberFormatException('The byte string must not be empty.');
    }
    $twosComplement = false;
    if ($signed) {
        $x = \ord($value[0]);
        if ($twosComplement = $x >= 0x80) {
            $value = ~$value;
        }
    }
    $number = self::fromBase(\bin2hex($value), 16);
    if ($twosComplement) {
        return $number->plus(1)
            ->negated();
    }
    return $number;
}