Visual Studio 11开发者预览中的BitScanForward64问题 [英] BitScanForward64 issue in Visual Studio 11 Developer Preview

问题描述

我完全是新写C的。我正在写一个辅助DLL（从C＃调用）来执行二进制操作。我得到一个标识符BitScanForward64未定义的错误。提供32位版本。我想这是因为我创建了一个Win32 DLL。

I am totally new to writing anything in C. I am writing a helper DLL (to be called from C#) that performs binary manipulation. I get an 'identifier "BitScanForward64" is undefined' error. The 32-bit version is available. I figure this is because I created a Win32 DLL.

然后我明白，64位版本可能只有一个特定的64位DLL（我假设一般对新的项目向导），我可能需要一个单独的32位和64位的DLL。是这种情况，或者我可以有一个DLL运行BitScanForward和BitScanForward64内在函数，如果是这样，我如何去创建它？

It then dawned on me that the 64 bit version may only be available to a specific 64 bit DLL (I assume "General" on the new project wizard), and that I may need a separate 32 bit and 64 bit dll. Is this the case, or can I have a single DLL that runs both the BitScanForward and BitScanForward64 intrinsics, and if so, how do I go about creating it?

这里是我当前的代码：

// C Functions.cpp : Defines the exported functions for the DLL application.

#include "stdafx.h"
//#include <intrin.h>
//#include <winnt.h>

int _stdcall LSB_i32(unsigned __int32 x)
{
    DWORD result;
    BitScanForward(&result, x);
    return (int)result;
}

int _stdcall MSB_i32(unsigned __int32 x)
{
    DWORD result;
    BitScanReverse(&result, x);
    return (int)result; 
}

int _stdcall LSB_i64(unsigned __int64 x)
{
    DWORD result;
    BitScanForward64(&result, x);
    return (int)result;
}

int _stdcall MSB_i64(unsigned __int64 x)
{
    DWORD result;
    BitScanReverse64(&result, x);
    return (int)result;
}

推荐答案

DLL来保存这两个操作，但是它将是一个仅x64的DLL（因此只能在64位进程中的64位操作系统上使用），如表中所示这里（还要注意，intrisics有一个 _ 前缀， BitScan * 64 函数可能需要这个，他们都使用它，而不管）。

It is possible to create a DLL to hold both these operations, but it would then be an x64 only DLL (and thus usable only on a 64-bit OS in a 64-bit process), as shown in the table here (also note that the intrisics have an _ prefixed to them, the BitScan*64 functions might require this, they all work with it regardless).

此链接详细信息在Visual Studio中创建一个基于x64的项目，从中你应该能够创建你的dll。

This link details creating a x64 based project in Visual Studio, from which you should be able to create your dll.

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