sysinfo.cpp

如何在Java程序中使用我们现有的DLL。因为这些DLLs并不是为在由Java创建的头文件中使用而编写的。这个问题的解决方法就是创建一个封装的DLL

#include <windows.h>
#include "sysinfo.h"

BOOL WINAPI DllMain(HANDLE hHandle, DWORD dwReason, LPVOID lpReserved)
{
	return TRUE;
}

JNIEXPORT jint JNICALL Java_sysInfo_getCPUSpeed(JNIEnv *, jclass)
{
	LARGE_INTEGER ulFreq, ulTicks, ulValue, ulStartCounter, ulEAX_EDX, ulResult;

	// it is number of ticks per seconds
	QueryPerformanceFrequency(&ulFreq);
	// current valueofthe performance counter
	
	QueryPerformanceCounter(&ulTicks);
	// calculate one second interval
	ulValue.QuadPart = ulTicks.QuadPart + ulFreq.QuadPart;
	// read time stamp counter
	// this asm instruction load the highorder 32 bit of the register into EDX
	// and the lower order 32 bits into EAX
	_asm 
	{
		rdtsc
			mov ulEAX_EDX.LowPart, EAX
			mov ulEAX_EDX.HighPart, EDX
	}
	
	// start no of ticks
	ulStartCounter.QuadPart = ulEAX_EDX.QuadPart;
	// loop for 1 second
	do 
	{
		QueryPerformanceCounter(&ulTicks);
	} while (ulTicks.QuadPart <= ulValue.QuadPart);
	
	// get the actual no of ticks
	_asm 
	{
		rdtsc
			mov ulEAX_EDX.LowPart, EAX
			mov ulEAX_EDX.HighPart, EDX
	}
	
	// calculate result
	ulResult.QuadPart = ulEAX_EDX.QuadPart - ulStartCounter.QuadPart;
	return (int)ulResult.QuadPart / 1000000;
}


JNIEXPORT jstring JNICALL Java_sysInfo_getCPUType(JNIEnv * env, jclass)
{
	static char pszCPUType[13];
	memset(pszCPUType, 0, 13);
	_asm 
	{
		mov eax, 0
		cpuid

		// getting information from EBX
		mov pszCPUType[0], bl
		mov pszCPUType[1], bh
		ror ebx, 16
		mov pszCPUType[2], bl
		mov pszCPUType[3], bh

		// getting information from EDX
		mov pszCPUType[4], dl
		mov pszCPUType[5], dh
		ror edx, 16
		mov pszCPUType[6], dl
		mov pszCPUType[7], dh

		// getting information from ECX
		mov pszCPUType[8], cl
		mov pszCPUType[9], ch
		ror ecx, 16
		mov pszCPUType[10], cl
		mov pszCPUType[11], ch
	}

	pszCPUType[12] = '\0';
	return env->NewStringUTF(pszCPUType);
}

JNIEXPORT jint JNICALL Java_sysInfo_getCPUFamily(JNIEnv *, jclass)
{
	int retVal;
	_asm 
	{
		mov eax, 1
		cpuid
		mov retVal, eax
	}

	return (retVal >> 8);
}

JNIEXPORT jint JNICALL Java_sysInfo_getCPUModal(JNIEnv *, jclass)
{
	int retVal;
	_asm 
	{
		mov eax, 1
		cpuid
		mov retVal, eax
	}

	return ((retVal >> 4 ) & 0x0000000f);
}

JNIEXPORT jint JNICALL Java_sysInfo_getCPUStepping(JNIEnv *, jclass)
{
	int retVal;
	_asm 
	{
		mov eax, 1
		cpuid
		mov retVal, eax
	}

	return (retVal & 0x0000000f);
}