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am a5087148: Reimplement clock(3) using clock_gettime(3)

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* commit 'a508714800242b294291060641ed35d719bdc857':
  Reimplement clock(3) using clock_gettime(3)
This commit is contained in:
Alex Van Brunt 2014-10-04 16:44:11 +00:00 committed by Android Git Automerger
commit 02542b3bbd
1 changed files with 7 additions and 6 deletions
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13
libc/bionic/clock.cpp
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@ -30,12 +30,13 @@
#include <sys/sysconf.h>
#include <sys/times.h>
#define NS_PER_S 1000000000 // No "private/bionic_constants.h" in lmp-dev.
// http://pubs.opengroup.org/onlinepubs/9699919799/functions/clock.html
clock_t clock() {
tms t;
times(&t);
// Although times(2) and clock(3) both use the type clock_t, the units are
// different. For times(2) it's pure clock ticks, but for clock(3) the unit
// is CLOCKS_PER_SEC, so we need to scale appropriately.
return (t.tms_utime + t.tms_stime) * (CLOCKS_PER_SEC / sysconf(_SC_CLK_TCK));
timespec ts;
if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) == -1) {
return -1;
}
return (ts.tv_sec * CLOCKS_PER_SEC) + (ts.tv_nsec / (NS_PER_S / CLOCKS_PER_SEC));
}