如何在PHP中执行适当的无符号右移? [英] How do I perform a proper unsigned right shift in PHP?

问题描述

是否有可能在PHP和Javascript中获得相同的结果?

Is this possible to get the same results in PHP and Javascript?

示例:

JavaScript

<script>

function urshift(a, b)
{
  return a >>> b;
}

document.write(urshift(10,3)+"<br />");
document.write(urshift(-10,3)+"<br />");
document.write(urshift(33, 33)+"<br />");
document.write(urshift(-10, -30)+"<br />");
document.write(urshift(-14, 5)+"<br />");

</script>

输出:

1
536870910
16
1073741821
134217727

PHP

function uRShift($a, $b) 
    { 
        if ($a < 0) 
        { 
            $a = ($a >> 1); 
            $a &= 2147483647; 
            $a |= 0x40000000; 
            $a = ($a >> ($b - 1)); 
        } else { 
            $a = ($a >> $b); 
        } 
        return $a; 
    }

echo uRShift(10,3)."<br />";
echo uRShift(-10,3)."<br />";
echo uRShift(33,33)."<br />";
echo uRShift(-10,-30)."<br />";
echo uRShift(-14,5)."<br />";

输出:

1
536870910
0
0
134217727

是否有可能获得相同的结果?

Is this possible to get the same results?

最接近我想要的功能在这里:

Closest function to what I want is here:

无符号右移功能不适用于负输入

感谢您的帮助.

推荐答案

尝试使用此功能:

function unsigned_shift_right($value, $steps) {
    if ($steps == 0) {
         return $value;
    }

    return ($value >> $steps) & ~(1 << (8 * PHP_INT_SIZE - 1) >> ($steps - 1));
}

基于您的代码示例的输出:

The output, based on your code sample:

1
536870910
16
1073741821
134217727

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