LXR linux/tools/perf/util/tsc.c

   1#include <linux/compiler.h>
   2#include <linux/types.h>
   3
   4#include "tsc.h"
   5
   6u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
   7{
   8        u64 t, quot, rem;
   9
  10        t = ns - tc->time_zero;
  11        quot = t / tc->time_mult;
  12        rem  = t % tc->time_mult;
  13        return (quot << tc->time_shift) +
  14               (rem << tc->time_shift) / tc->time_mult;
  15}
  16
  17u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
  18{
  19        u64 quot, rem;
  20
  21        quot = cyc >> tc->time_shift;
  22        rem  = cyc & ((1 << tc->time_shift) - 1);
  23        return tc->time_zero + quot * tc->time_mult +
  24               ((rem * tc->time_mult) >> tc->time_shift);
  25}
  26
  27u64 __weak rdtsc(void)
  28{
  29        return 0;
  30}
  31