转换C到PHP的CRC16功能 [英] Convert C to PHP for CRC16 Function

问题描述

我需要转换C $ C $ç到PHP的帮助。以下是C code：

I need help in converting C code into PHP. The following is the C Code:

static const U16 crctab16[] = { 0x0000, 0x1189, ... };

U16 GetCrc16(const U8* pData, int nLength)
{
  U16 fcs = 0xffff;
  while(nLength > 0)
  {
    fcs = (fcs >> 8) ^ crctab16[fcs ^ *pData) & 0xff];
    nLength--; pData++;
  }
  return ~fcs;
}

我有以下PHP code，我已设法迄今转换：

I have the following PHP code that I have managed to convert thus far:

$crctab16 = array(0x0000, 0x1189, ... );

function getCrc16($pData)
{
    $hexdata = pack('H*',$pData);
    $nLength = strlen($hexdata);
    $fcs = 0xFFFF;
    $pos = 0;
    while($nLength > 0)
    {
        $fcs = ($fcs >> 8) ^ $crctab16[($fcs ^ $hexdata[$pos]) & 0xFF];
        $nLength--;
        $pos++;
    }
    return ~$fcs;
}

我试图运行下面的code：

I have tried to run the following code:

$str = "0A1344010400010005"; 
var_dump(getCrc16($str));
var_dump(bin2hex(getCrc16($str))); // result supposed to be 08 45

这似乎是显示错误的结果。当我试图替换 $ STR 与其他值，结果将始终是相同的。

It seems to be showing the wrong result. When I tried to substitute $str with other values, the result will always be the SAME.

我相信有可能是坏了我的PHP code。但是，我似乎无法找出这个原因。

I believe there might be something wrong with my PHP code. But, I cannot seem to figure out the cause of this.

推荐答案

我设法弄清楚这个解决方案。由于@nhahtdh，@Carsten和@odiszapc谁都有帮助。

I have managed to figure out the solution for this. Thanks to @nhahtdh, @Carsten, and @odiszapc who have helped.

这是正确的PHP函数：

This is the correct PHP function:

function getCrc16($pData)
{
    $hexdata = pack('H*',$pData);
    $nLength = strlen($hexdata);
    $fcs = 0xFFFF;
    $pos = 0;
    while($nLength > 0)
    {
        $fcs = ($fcs >> 8) ^ $crctab16[($fcs ^ ord($hexdata[$pos])) & 0xFF];
        $nLength--;
        $pos++;
    }
    return ~$fcs;
}

看来，我需要 ORD在字节格式的数据（）功能。我已经想通了这一点继@Carsten提供的CRC16例子。

It seems that I need to ord() function in the byte format data. I have figured this out following the CRC16 example provided by @Carsten.

感谢你这么多的家伙！

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