linux下软件定时器的实现

/*********************************************** Author:Charles Stone Email:sc8312@qq.com;sc8312@sohu.com QQ:13148567 Corporation:Pulante Dirigible Function:Linux下实现毫秒级的软件定时 Notice:该定时器最小延迟依赖于系统HZ，故不一定能满足毫秒级定时 ***********************************************/ #include<sys/types.h> #include<sys/stat.h> #include<fcntl.h> #include<unistd.h> #include<termios.h> #include<errno.h> #include<stdio.h> #include<stdlib.h> #include<time.h> #include<sys/time.h> #include<sys/times.h> #include<sys/ioctl.h> #include<signal.h> #include<string.h> #include"stimer.h" static pstimer stimer_head=NULL,stimer_tail=NULL; static int stimer_mex=0; static unsigned long stimer_const=1; void timer_handle(int signo) { pstimer tmp; while(stimer_mex); stimer_mex=1; for(tmp=stimer_head;tmp;tmp=tmp->next) { if (tmp->enable) { if(tmp->msec)tmp->msec--; if(!tmp->msec) { if(tmp->handle)tmp->handle(tmp->timer_id); if(!tmp->intermsec)tmp->enable=0; else tmp->msec=tmp->intermsec; } } } stimer_mex=0; } pstimer stimer_create(int stimer_id) { pstimer tmp; for(tmp=stimer_head;tmp;tmp=tmp->next) { if(tmp->timer_id==stimer_id)return NULL; /* 定时器 stimer_id 存在返回NULL*/ } if((tmp=(pstimer)malloc(sizeof(stimer)))==NULL)return NULL; /* 创建定时器结构体,在下面初始化并安装 */ tmp->timer_id=stimer_id; tmp->next=NULL; tmp->enable=0; if(stimer_tail==NULL) { tmp->pre=NULL; stimer_head=stimer_tail=tmp; } else { tmp->pre=stimer_tail; stimer_tail->next=tmp; stimer_tail=tmp; } return tmp; /* 创建成功返回pstimer类型指针 */ } int stimer_set(pstimer pst,unsigned long msec,void (*handle)(int),int mode) { if (pst==NULL)return -1; pst->msec=msec/stimer_const; if(msec%stimer_const)pst->msec++; pst->handle=handle; switch(mode) { case STIMER_CYCLE: pst->intermsec=pst->msec; break; case STIMER_ONCE: pst->intermsec=0; break; default: return -1; } pst->enable=1; return 0; } int stimer_reset(pstimer pst) { if(pst==NULL)return -1; pst->msec=pst->intermsec; return 0; } int stimer_pause(pstimer pst) { if(pst==NULL)return -1; pst->enable=0; return 0; } int stimer_continue(pstimer pst) { if(pst==NULL)return -1; pst->enable=1; return 0; } int stimer_del(pstimer pst) { if(stimer_mex)return 1; stimer_mex^=1; if(stimer_mex==0)return 1; if(stimer_tail==NULL)return -1; if(pst->pre==NULL) { if((stimer_head=pst->next)) stimer_head->pre=NULL; } else { pst->pre->next=pst->next; pst->next->pre=pst->pre; } if(pst->next==NULL)stimer_tail=pst->pre; free(pst); stimer_mex=0; return 0; } int stimer_init() { //unsigned long SYS_HZ; struct sigaction tact; struct itimerval value; //SYS_HZ=sysconf(_SC_CLK_TCK); //stimer_const=1000/SYS_HZ; stimer_const=1000ul/sysconf(_SC_CLK_TCK); //printf("System's HZ=%lu\nstimer_const=%lu\n",SYS_HZ,stimer_const); tact.sa_handler = timer_handle; tact.sa_flags = 0; sigaction(SIGALRM,&tact,NULL); value.it_value.tv_sec = 0; value.it_value.tv_usec = 1000; value.it_interval.tv_sec = 0; value.it_interval.tv_usec = 1000; return setitimer(ITIMER_REAL,&value,NULL); } int stimer_release() { struct itimerval value; value.it_value.tv_sec = 0; value.it_value.tv_usec = 0; value.it_interval.tv_sec = 0; value.it_interval.tv_usec = 0; return setitimer(ITIMER_REAL,&value,NULL); }