1#include <time.h> 2#include <limits.h> 3 4int __clock_gettime(clockid_t, struct timespec *); 5 6clock_t clock() 7{ 8 struct timespec ts; 9 10 if (__clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts)) 11 return -1; 12 13 if (ts.tv_sec > LONG_MAX/1000000 14 || ts.tv_nsec/1000 > LONG_MAX-1000000*ts.tv_sec) 15 return -1; 16 17 return ts.tv_sec*1000000 + ts.tv_nsec/1000; 18} 19