Plan 9 from Bell Labs’s /usr/web/sources/plan9/sys/src/libc/9sys/cputime.c
#include <u.h> #include <libc.h> #define HZ 1000 double cputime(void) { long t[4]; int i; times(t); for(i=1; i<4; i++) t[0] += t[i]; return t[0] / (double)HZ; }