ghost/timer.m

#import "timer.h"

struct timespec subts(struct timespec t1, struct timespec t2) {
    return (struct timespec) {
        .tv_sec = t1.tv_sec - t2.tv_sec,
        .tv_nsec = t1.tv_nsec - t2.tv_nsec,
    };
}

struct timespec addts(struct timespec t1, struct timespec t2) {
    return (struct timespec) {
        .tv_sec = t1.tv_sec + t2.tv_sec,
        .tv_nsec = t1.tv_nsec + t2.tv_nsec,
    };
}

double timespec_to_double(struct timespec ts) {
	return ((double)(ts.tv_sec) + ((double)(ts.tv_nsec) / NSEC_PER_SEC));
}

@implementation Timer
-(id) init {
    self = [super init];
    running = false;
    paused = false;
    pause_start = (struct timespec){0};
    pause_current = (struct timespec){0};
    start = (struct timespec){0};
    current = (struct timespec){0};
    diff = (struct timespec){0};
    return self;
}

-(void) start {
    clock_gettime(CLOCK_REALTIME, &start);
    running = true;
}

-(void) pause {
    clock_gettime(CLOCK_REALTIME, &pause_start);
    paused = true;
}

-(void) resume {
    struct timespec t = subts(pause_current, pause_start);
    diff = addts(diff, t);
    paused = false;
}

-(void) stop {
    running = false;
}

-(void) reset {
    running = false;
    start = (struct timespec){0};
    current = start;
}

-(void) tick {
    if (!paused) {
        clock_gettime(CLOCK_REALTIME, &current);
    } else {
        clock_gettime(CLOCK_REALTIME, &pause_current);
    }
}

-(struct timespec) time {
    //time running = (current - start) - pause
    struct timespec time = subts(current, start);
    return subts(time, diff);

}

-(char *) timeString {
    //super simple format
    static char buffer[100];
    struct timespec time = subts(current, start);
    time = subts(time, diff);

    double dbl = timespec_to_double(time);

    sprintf(buffer, "%.02lf", dbl);
    return buffer;
}

@end