模拟线程切换

古月不傲

链接：
https://www.bilibili.com/video/av68700135?p=47
http://blog.initm.com/threadswitch.shtml

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//头文件 #include <iostream> #include <Windows.h>   using namespace std;   #pragma once   //最大支持的线程数 #define MAXGMTHREAD 100   //线程信息的结构 typedef struct {     char* name;                     //线程名     int Flags;                      //线程状态     int SleepMillsecondDot;         //休眠时间       void* initialStack;             //线程堆栈起始位置     void* StackLimit;               //线程堆栈界限     void* KernelStack;              //线程堆栈当前位置，也就是ESP       void* lpParameter;              //线程函数的参数     void(*func)(void* lpParameter); //线程函数指针 }GMThread_t;   void GMSleep(int MilliSeconds); int RegisterGMThread(char* name, void(*func)(void*lpParameter), void* lpParameter); void Scheduling(void);   //源文件 #include "ThreadSwitch.h"   //定义线程栈的大小 #define GMTHREADSTACKSIZE 0x80000   //当前线程的索引 int CurrentThreadIndex = 0;   //线程的列表 GMThread_t GMThreadList[MAXGMTHREAD] = { NULL, 0 };   //线程状态的标志 enum FLAGS {     GMTHREAD_CREATE = 0x1,     GMTHREAD_READY = 0x2,     GMTHREAD_SLEEP = 0x4,     GMTHREAD_EXIT = 0x8, };   //启动线程的函数 void GMThreadStartup(GMThread_t* GMThreadp) {     GMThreadp->func(GMThreadp->lpParameter);     GMThreadp->Flags = GMTHREAD_EXIT;        //执行完线程退出     Scheduling();       return; }   //空闲线程的函数 void IdleGMThread(void* lpParameter) {     printf("IdleGMThread---------------\n");     Scheduling();     return; }   //向栈中压入一个uint值 void PushStack(unsigned int** Stackpp, unsigned int v) {     *Stackpp -= 1;  //-4     **Stackpp = v;  //push v       return; }   //初始化线程的信息 void initGMThread(GMThread_t* GMThreadp, char* name, void(*func)(void* lpParameter), void* lpParameter) {     unsigned char* StackPages;     unsigned int* StackDWordParam;     GMThreadp->Flags = GMTHREAD_CREATE;     GMThreadp->name = name;     GMThreadp->func = func;     GMThreadp->lpParameter = lpParameter;     //分配栈空间     StackPages = (unsigned char*)VirtualAlloc(NULL, GMTHREADSTACKSIZE, MEM_COMMIT, PAGE_READWRITE);     ZeroMemory(StackPages, GMTHREADSTACKSIZE);     GMThreadp->initialStack = StackPages + GMTHREADSTACKSIZE;     StackDWordParam = (unsigned int*)GMThreadp->initialStack;     //入栈     PushStack(&StackDWordParam, (unsigned int)GMThreadp);     PushStack(&StackDWordParam, (unsigned int)0);     PushStack(&StackDWordParam, (unsigned int)GMThreadStartup);     PushStack(&StackDWordParam, (unsigned int)5);     PushStack(&StackDWordParam, (unsigned int)7);     PushStack(&StackDWordParam, (unsigned int)6);     PushStack(&StackDWordParam, (unsigned int)3);     PushStack(&StackDWordParam, (unsigned int)2);     PushStack(&StackDWordParam, (unsigned int)1);     PushStack(&StackDWordParam, (unsigned int)0);     //当前线程的栈顶     GMThreadp->KernelStack = StackDWordParam;     GMThreadp->Flags = GMTHREAD_READY;     return; }   //将一个函数注册为单独线程执行 int RegisterGMThread(char* name, void(*func)(void*lpParameter), void* lpParameter) {     int i = 0;     for (i = 1; GMThreadList[i].name; i++) {         if (0 == _stricmp(GMThreadList[i].name, name)) {             break;         }     }     initGMThread(&GMThreadList[i], name, func, lpParameter);       return (i & 0x55AA0000); }   //切换线程  线程切换的本质 也就是切换堆栈 __declspec(naked) void SwitchContext(GMThread_t* SrcGMThreadp, GMThread_t* DstGMThreadp) {     __asm {         push ebp         mov ebp, esp         push edi         push esi         push ebx         push ecx         push edx         push eax           mov esi, SrcGMThreadp         mov edi, DstGMThreadp         mov[esi + GMThread_t.KernelStack], esp  //保存源线程栈顶         //经典线程切换，另外一个线程复活         mov esp, [edi + GMThread_t.KernelStack] //切换线程 也就是切换堆栈         //下面切换寄存器         pop eax         pop edx         pop ecx         pop ebx         pop esi         pop edi         pop ebp         ret //执行GMThreadStartup     } }   //这个函数会让出cpu，从队列里重新选择一个线程执行 void Scheduling(void) {     int i;     int TickCount;     GMThread_t* SrcGMThreadp;       GMThread_t* DstGMThreadp;       TickCount = GetTickCount();     SrcGMThreadp = &GMThreadList[CurrentThreadIndex];   //源线程     DstGMThreadp = &GMThreadList[0];                    //目标线程       //寻找就绪线程    没找到就执行空闲线程     for (i = 1; GMThreadList[i].name; i++) {         //如果线程是休眠状态         if (GMThreadList[i].Flags & GMTHREAD_SLEEP) {             if (TickCount > GMThreadList[i].SleepMillsecondDot) {                 //切换就绪状态                 GMThreadList[i].Flags = GMTHREAD_READY;             }         }         //如果线程是就绪状态         if (GMThreadList[i].Flags & GMTHREAD_READY) {             //找到就绪线程             DstGMThreadp = &GMThreadList[i];             break;         }     }     //得到下标     CurrentThreadIndex = DstGMThreadp - GMThreadList;     //线程切换     SwitchContext(SrcGMThreadp, DstGMThreadp);     return; }   void GMSleep(int MilliSeconds) {     GMThread_t* GMThreadp;     GMThreadp = &GMThreadList[CurrentThreadIndex];     if (GMThreadp->Flags != 0) {         GMThreadp->Flags = GMTHREAD_SLEEP;       //当前线程挂入等待链表         GMThreadp->SleepMillsecondDot = GetTickCount() + MilliSeconds;     }     //寻找新的就绪线程     Scheduling();     return; }   //测试 #include "ThreadSwitch.h"   extern int CurrentThreadIndex;   extern GMThread_t GMThreadList[MAXGMTHREAD]; void Thread1(void*) {     while (1) {         printf("Thread1\n");         GMSleep(100);     } } void Thread2(void*) {     while (1) {         printf("Thread2\n");         GMSleep(200);     } }   void Thread3(void*) {     while (1) {         printf("Thread3\n");         GMSleep(300);     } }   void Thread4(void*) {     while (1) {         printf("Thread4\n");         GMSleep(200);     } }     int main() {     char name1[20] = "Thread1";     char name2[20] = "Thread2";     char name3[20] = "Thread3";     char name4[20] = "Thread4";     RegisterGMThread(name1, Thread1, NULL);     RegisterGMThread(name2, Thread2, NULL);     RegisterGMThread(name3, Thread3, NULL);     RegisterGMThread(name4, Thread4, NULL);       while (TRUE) {         Sleep(20);         Scheduling();     }       return 0; }

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楼主也在B站？

yywapj

还有说明，真心辛苦啦，厉害

xlxjyxs

支持一下

kilasuelika

厉害厉害

zoiitylj

牛逼，切换线程是操作系统的事，能自己切换不是可以给特定线程多安排时间片了？GetTickCount的粒度不如timegettime