42 lines
906 B
PHP
42 lines
906 B
PHP
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<?php
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declare(strict_types = 1);
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namespace BaconQrCode\Common;
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/**
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* General bit utilities.
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*
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* All utility methods are based on 32-bit integers and also work on 64-bit
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* systems.
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*/
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final class BitUtils
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{
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private function __construct()
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{
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}
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/**
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* Performs an unsigned right shift.
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*
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* This is the same as the unsigned right shift operator ">>>" in other
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* languages.
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*/
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public static function unsignedRightShift(int $a, int $b) : int
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{
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return (
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$a >= 0
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? $a >> $b
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: (($a & 0x7fffffff) >> $b) | (0x40000000 >> ($b - 1))
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);
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}
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/**
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* Gets the number of trailing zeros.
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*/
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public static function numberOfTrailingZeros(int $i) : int
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{
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$lastPos = strrpos(str_pad(decbin($i), 32, '0', STR_PAD_LEFT), '1');
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return $lastPos === false ? 32 : 31 - $lastPos;
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}
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}
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