C# 使用汇编

本文告诉大家如何在 C# 里面使用汇编代码

请看

通过这个方法在 dotnet core 获取 CPU 信息

[StructLayout(LayoutKind.Sequential)]

internal ref struct CpuIdInfo

{

    public uint Eax;

    public uint Ebx;

    public uint Ecx;

    public uint Edx;

    public static void AppendAsString(StringBuilder builder,uint value)

    {

        var val = value;

        while (val != 0)

        {

            builder.Append((char) (val & 0xFF));

            val >>= 8;

        }

    }

    public string GetString()

    {

        StringBuilder ret = new StringBuilder(16);

        AppendAsString(ret,Ebx);

        AppendAsString(ret,Edx);

        AppendAsString(ret,Ecx);

        return ret.ToString();

    }

}

internal sealed class CpuIdAssemblyCode

    : IDisposable

{

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]

    private delegate void CpuIDDelegate(int level, ref CpuIdInfo cpuId);

    private IntPtr _codePointer;

    private uint _size;

    private CpuIDDelegate _delegate;

    public CpuIdAssemblyCode()

    {

        byte[] codeBytes = (IntPtr.Size == 4) ? x86CodeBytes : x64CodeBytes;

        _size = (uint) codeBytes.Length;

        _codePointer = NativeMethods.Kernel32.VirtualAlloc(

                IntPtr.Zero,

                new UIntPtr(_size),

                AllocationType.COMMIT | AllocationType.RESERVE,

                MemoryProtection.EXECUTE_READWRITE

            );

        Marshal.Copy(codeBytes, 0, _codePointer, codeBytes.Length);

#if NET40

        _delegate = (CpuIDDelegate) Marshal.GetDelegateForFunctionPointer(_codePointer, typeof(CpuIDDelegate));

#else

        _delegate = Marshal.GetDelegateForFunctionPointer<CpuIDDelegate>(_codePointer);

#endif

    }

    ~CpuIdAssemblyCode()

    {

        Dispose(false);

    }

    public void Call(int level, ref CpuIdInfo cpuInfo)

    {

        _delegate(level, ref cpuInfo);

    }

    public void Dispose()

    {

        Dispose(true);

        GC.SuppressFinalize(this);

    }

    private void Dispose(bool disposing)

    {

        NativeMethods.Kernel32.VirtualFree(_codePointer, _size, 0x8000);

    }

    // Basic ASM strategy --

    // void x86CpuId(int level, byte* buffer)

    // {

    //    eax = level

    //    cpuid

    //    buffer[0] = eax

    //    buffer[4] = ebx

    //    buffer[8] = ecx

    //    buffer[12] = edx

    // }

    private readonly static byte[] x86CodeBytes =

    {

    0x55,                   // push        ebp

    0x8B, 0xEC,             // mov         ebp,esp

    0x53,                   // push        ebx

    0x57,                   // push        edi

    0x8B, 0x45, 0x08,       // mov         eax, dword ptr [ebp+8] (move level into eax)

    0x0F, 0xA2,              // cpuid

    0x8B, 0x7D, 0x0C,       // mov         edi, dword ptr [ebp+12] (move address of buffer into edi)

    0x89, 0x07,             // mov         dword ptr [edi+0], eax  (write eax, ... to buffer)

    0x89, 0x5F, 0x04,       // mov         dword ptr [edi+4], ebx

    0x89, 0x4F, 0x08,       // mov         dword ptr [edi+8], ecx

    0x89, 0x57, 0x0C,       // mov         dword ptr [edi+12],edx 

    0x5F,                   // pop         edi

    0x5B,                   // pop         ebx

    0x8B, 0xE5,             // mov         esp,ebp

    0x5D,                   // pop         ebp

    0xc3                    // ret

    };

    private readonly static byte[] x64CodeBytes =

    {

    0x53,                       // push rbx    this gets clobbered by cpuid

    // rcx is level

    // rdx is buffer.

    // Need to save buffer elsewhere, cpuid overwrites rdx

    // Put buffer in r8, use r8 to reference buffer later.

    // Save rdx (buffer addy) to r8

    0x49, 0x89, 0xd0,           // mov r8,  rdx

    // Move ecx (level) to eax to call cpuid, call cpuid

    0x89, 0xc8,                 // mov eax, ecx

    0x0F, 0xA2,                 // cpuid

    // Write eax et al to buffer

    0x41, 0x89, 0x40, 0x00,     // mov    dword ptr [r8+0],  eax

    0x41, 0x89, 0x58, 0x04,     // mov    dword ptr [r8+4],  ebx

    0x41, 0x89, 0x48, 0x08,     // mov    dword ptr [r8+8],  ecx

    0x41, 0x89, 0x50, 0x0c,     // mov    dword ptr [r8+12], edx

    0x5b,                       // pop rbx

    0xc3                        // ret

    };

}

使用方法

var asmCode = new CpuIdAssemblyCode();

CpuIdInfo info = new CpuIdInfo();

asmCode.Call(0, ref info);

asmCode.Dispose();

string ret= info.GetString();

c# - How can I get CPU name in .NET Core? - Stack Overflow

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C# 使用汇编

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