1 /* The kernel call implemented in this file: 2 * m_type: SYS_SETALARM 3 * 4 * The parameters for this kernel call are: 5 * m_lsys_krn_sys_setalarm.exp_time (alarm's expiration time) 6 * m_lsys_krn_sys_setalarm.abs_time (expiration time is absolute?) 7 * m_lsys_krn_sys_setalarm.time_left (return seconds left of previous) 8 */ 9 10 #include "kernel/system.h" 11 12 #include <minix/endpoint.h> 13 #include <assert.h> 14 15 #if USE_SETALARM 16 17 static void cause_alarm(int proc_nr_e); 18 19 /*===========================================================================* 20 * do_setalarm * 21 *===========================================================================*/ 22 int do_setalarm(struct proc * caller, message * m_ptr) 23 { 24 /* A process requests a synchronous alarm, or wants to cancel its alarm. */ 25 long exp_time; /* expiration time for this alarm */ 26 int use_abs_time; /* use absolute or relative time */ 27 minix_timer_t *tp; /* the process' timer structure */ 28 clock_t uptime; /* placeholder for current uptime */ 29 30 /* Extract shared parameters from the request message. */ 31 exp_time = m_ptr->m_lsys_krn_sys_setalarm.exp_time; 32 use_abs_time = m_ptr->m_lsys_krn_sys_setalarm.abs_time; 33 if (! (priv(caller)->s_flags & SYS_PROC)) return(EPERM); 34 35 /* Get the timer structure and set the parameters for this alarm. */ 36 tp = &(priv(caller)->s_alarm_timer); 37 38 /* Return the ticks left on the previous alarm. */ 39 uptime = get_monotonic(); 40 if (!tmr_is_set(tp)) { 41 m_ptr->m_lsys_krn_sys_setalarm.time_left = TMR_NEVER; 42 } else if (tmr_is_first(uptime, tp->tmr_exp_time)) { 43 m_ptr->m_lsys_krn_sys_setalarm.time_left = tp->tmr_exp_time - uptime; 44 } else { 45 m_ptr->m_lsys_krn_sys_setalarm.time_left = 0; 46 } 47 48 /* For the caller's convenience, also return the current time. */ 49 m_ptr->m_lsys_krn_sys_setalarm.uptime = uptime; 50 51 /* 52 * Finally, (re)set the timer depending on the expiration time. Note that 53 * an absolute time of zero is as valid as any other absolute value, so only 54 * a relative time value of zero resets the timer. 55 */ 56 if (!use_abs_time && exp_time == 0) { 57 reset_kernel_timer(tp); 58 } else { 59 if (!use_abs_time) 60 exp_time += uptime; 61 set_kernel_timer(tp, exp_time, cause_alarm, caller->p_endpoint); 62 } 63 return(OK); 64 } 65 66 /*===========================================================================* 67 * cause_alarm * 68 *===========================================================================*/ 69 static void cause_alarm(int proc_nr_e) 70 { 71 /* Routine called if a timer goes off and the process requested a synchronous 72 * alarm. The process number is stored as the timer argument. Notify that 73 * process with a notification message from CLOCK. 74 */ 75 mini_notify(proc_addr(CLOCK), proc_nr_e); /* notify process */ 76 } 77 78 #endif /* USE_SETALARM */ 79