diff options
Diffstat (limited to '')
| -rw-r--r-- | timer.c | 136 |
1 files changed, 76 insertions, 60 deletions
@@ -1,7 +1,7 @@ /* $Id$ * $URL$ * - * generic timer handling + * Generic timer handling. * * Copyright (C) 2003, 2004 Michael Reinelt <michael@reinelt.co.at> * Copyright (C) 2004 The LCD4Linux Team <lcd4linux-devel@users.sourceforge.net> @@ -72,19 +72,21 @@ #include <dmalloc.h> #endif +/* FIXME: CLOCK_SKEW_DETECT_TIME_IN_S should have a higher value */ + /* delay in seconds between timer events that is considered as being induced by clock skew */ #define CLOCK_SKEW_DETECT_TIME_IN_S 1 /* structure for storing all relevant data of a single timer */ typedef struct TIMER { - /* function of type callback(void *data) that will be called when - the timer is processed; it will also be used to identify a - specific timer */ + /* pointer to function of type void func(void *data) that will be + called when the timer is processed; it will also be used to + identify a specific timer */ void (*callback) (void *data); - /* data which will be passed to the callback function; it will - also be used to identify a specific timer */ + /* pointer to data which will be passed to the callback function; + it will also be used to identify a specific timer */ void *data; /* struct to hold the time (in seconds and milliseconds since the @@ -98,17 +100,16 @@ typedef struct TIMER { it is deleted (value of 0) or only once (all other values) */ int one_shot; - /* marks timers as being active (so it will get processed) or + /* marks timer as being active (so it will get processed) or inactive (which means the timer has been deleted and its allocated memory may be re-used) */ int active; } TIMER; - /* number of allocated timer slots */ int nTimers = 0; -/* pointer to memory used for storing the timer slots */ +/* pointer to memory allocated for storing the timer slots */ TIMER *Timers = NULL; @@ -137,7 +138,7 @@ static void timer_inc(struct timeval *tv, const int interval) int timer_remove(void (*callback) (void *data), void *data) -/* Remove a new timer with given callback and data. +/* Remove a timer with given callback and data. callback (void pointer): function of type void func(void *data); here, it will be used to identify the timer @@ -146,24 +147,29 @@ int timer_remove(void (*callback) (void *data), void *data) function; here, it will be used to identify the timer return value (integer): returns a value of 0 on successful timer - deletion; otherwise returns a value of -1 + removal; otherwise returns a value of -1 */ { - int i; /* current timer's ID */ + int timer; /* current timer's ID */ /* loop through the timer slots and try to find the specified timer slot by looking for its settings */ - for (i = 0; i < nTimers; i++) { - if (Timers[i].callback == callback && Timers[i].data == data && Timers[i].active) { + for (timer = 0; timer < nTimers; timer++) { + /* skip inactive (i.e. deleted) timers */ + if (Timers[timer].active == 0) + continue; + + if (Timers[timer].callback == callback && Timers[timer].data == data) { /* we have found the timer slot, so mark it as being inactive; - we will not actually delete the timer, so its allocated + we will not actually delete the slot, so its allocated memory may be re-used */ - Timers[i].active = 0; + Timers[timer].active = 0; /* signal successful timer removal */ return 0; } } + /* we have NOT found the timer slot, so signal failure by returning a value of -1 */ return -1; @@ -192,26 +198,30 @@ int timer_add(void (*callback) (void *data), void *data, const int interval, con creation; otherwise returns a value of -1 */ { - int i; /* current timer's ID */ + int timer; /* current timer's ID */ struct timeval now; /* struct to hold current time */ /* try to minimize memory usage by looping through the timer slots and looking for an inactive timer */ - for (i = 0; i < nTimers; i++) { - if (Timers[i].active == 0) - /* we've just found one, so let's reuse it ("i" holds its ID) - by breaking the loop */ + for (timer = 0; timer < nTimers; timer++) { + if (Timers[timer].active == 0) { + /* we've just found one, so let's reuse it ("timer" holds its + ID) by breaking the loop */ break; + } } /* no inactive timers (or none at all) found, so we have to add a new timer slot */ - if (i >= nTimers) { + if (timer >= nTimers) { /* increment number of timers and (re-)allocate memory used for storing the timer slots */ nTimers++; Timers = realloc(Timers, nTimers * sizeof(*Timers)); + /* make sure "timer" points to valid memory */ + timer = nTimers - 1; + /* realloc() has failed */ if (Timers == NULL) { /* restore old number of timers */ @@ -225,21 +235,21 @@ int timer_add(void (*callback) (void *data), void *data, const int interval, con /* get current time so the timer triggers immediately */ gettimeofday(&now, NULL); - /* fill in timer data */ - Timers[i].callback = callback; - Timers[i].data = data; - Timers[i].when = now; - Timers[i].interval = interval; - Timers[i].one_shot = one_shot; + /* initialize timer data */ + Timers[timer].callback = callback; + Timers[timer].data = data; + Timers[timer].when = now; + Timers[timer].interval = interval; + Timers[timer].one_shot = one_shot; /* set timer to active so that it is processed and not overwritten - by the memory optimisation routine above */ - Timers[i].active = 1; + by the memory optimization routine above */ + Timers[timer].active = 1; /* one-shot timers should NOT fire immediately, so delay them by a single timer interval */ if (one_shot) { - timer_inc(&Timers[i].when, interval); + timer_inc(&Timers[timer].when, interval); } /* signal successful timer creation */ @@ -279,17 +289,20 @@ int timer_add_late(void (*callback) (void *data), void *data, const int interval return -1; } - int i; /* current timer's ID */ + int timer; /* current timer's ID */ /* loop through the timer slots and try to find the new timer slot by looking for its settings */ - for (i = 0; i < nTimers; i++) { - if (Timers[i].callback == callback && Timers[i].data == data && Timers[i].active - && Timers[i].interval == interval) { + for (timer = 0; timer < nTimers; timer++) { + /* skip inactive (i.e. deleted) timers */ + if (Timers[timer].active == 0) + continue; + + if (Timers[timer].callback == callback && Timers[timer].data == data && Timers[timer].interval == interval) { /* we have found the new timer slot, so unmask it by setting its "one_shot" variable to the REAL value; then signal successful timer creation */ - Timers[i].one_shot = one_shot; + Timers[timer].one_shot = one_shot; /* signal successful timer creation */ return 0; @@ -317,73 +330,76 @@ int timer_process(struct timespec *delay) /* get current time to check which timers need processing */ gettimeofday(&now, NULL); - /* sanity check; at least one timer should need processing */ - if (nTimers == 0) { + /* sanity check; by now, at least one timer should be + instantiated */ + if (nTimers <= 0) { /* otherwise, print an error and return a value of -1 to signal an error */ - error("Huh? Not one single timer to process? Dazed and confused..."); + error("Huh? Not even a single timer to process? Dazed and confused..."); return -1; } - int i; /* current timer's ID */ + int timer; /* current timer's ID */ /* process all expired timers */ - for (i = 0; i < nTimers; i++) { + for (timer = 0; timer < nTimers; timer++) { /* skip inactive (i.e. deleted) timers */ - if (Timers[i].active == 0) + if (Timers[timer].active == 0) continue; + /* check whether current timer needs to be processed, i.e. the timer's triggering time is less than or equal to the current time; according to the man page of timercmp(), this avoids using the operators ">=", "<=" and "==" which might be broken on some systems */ - if (!timercmp(&Timers[i].when, &now, >)) { + if (!timercmp(&Timers[timer].when, &now, >)) { /* if the timer's callback function has been set, call it and pass the corresponding data */ - if (Timers[i].callback != NULL) { - Timers[i].callback(Timers[i].data); + if (Timers[timer].callback != NULL) { + Timers[timer].callback(Timers[timer].data); } /* check for one-shot timers */ - if (Timers[i].one_shot) { + if (Timers[timer].one_shot) { /* mark one-shot timer as inactive (which means the timer has been deleted and its allocated memory may be re-used) */ - Timers[i].active = 0; + Timers[timer].active = 0; } else { /* otherwise, respawn timer by adding one triggering interval to its triggering time */ - timer_inc(&Timers[i].when, Timers[i].interval); + timer_inc(&Timers[timer].when, Timers[timer].interval); } } } - int min = -1; /* ID of the next upcoming timer */ + int next_timer = -1; /* ID of the next upcoming timer */ /* loop through the timer slots and try to find the next upcoming timer */ - for (i = 0; i < nTimers; i++) { + for (timer = 0; timer < nTimers; timer++) { /* skip inactive (i.e. deleted) timers */ - if (Timers[i].active == 0) + if (Timers[timer].active == 0) continue; /* if this is the first timer that we check, mark it as the next upcoming timer; otherwise, we'll have nothing to compare against in this loop */ - if (min < 0) - min = i; + if (next_timer < 0) + next_timer = timer; /* check whether current timer needs processing prior to the one selected */ - else if (timercmp(&Timers[i].when, &Timers[min].when, <)) + else if (timercmp(&Timers[timer].when, &Timers[next_timer].when, <)) { /* if so, mark it as the next upcoming timer */ - min = i; + next_timer = timer; + } } /* sanity check; we should by now have found the next upcoming timer */ - if (min < 0) { + if (next_timer < 0) { /* otherwise, print an error and return a value of -1 to signal an error */ - error("Huh? Not one single timer left? Dazed and confused..."); + error("Huh? Not even a single timer left? Dazed and confused..."); return -1; } @@ -397,7 +413,7 @@ int timer_process(struct timespec *delay) /* calculate delay to the next upcoming timer event and store it in "diff" */ - timersub(&Timers[min].when, &now, &diff); + timersub(&Timers[next_timer].when, &now, &diff); /* for negative delays, set "diff" to the Epoch so the next update is triggered immediately */ @@ -417,7 +433,7 @@ int timer_process(struct timespec *delay) /* update time stamp and timer */ /* FIXME: shouldn't we update *all* timers? */ gettimeofday(&now, NULL); - Timers[min].when = now; + Timers[next_timer].when = now; } /* finally, set passed timespec "delay" to "diff" ... */ @@ -439,8 +455,8 @@ void timer_exit(void) /* reset number of allocated timer slots */ nTimers = 0; - if (Timers != NULL) { /* free memory used for storing the timer slots */ + if (Timers != NULL) { free(Timers); Timers = NULL; } |