#11 fix to get CPU frequency on Linux

[tom zhou]

Index: src/common.cpp

--- src/common.cpp (revision 458)
+++ src/common.cpp (working copy)
@@ -43,6 +43,7 @@
#include <cstring>
#include <cerrno>
#include <unistd.h></unistd.h></cerrno></cstring>

• include <stdio.h></stdio.h>

  ifdef OSX

  #include <mach mach_time.h=""></mach>

  endif

  @@ -155,6 +156,35 @@
  mach_timebase_info_data_t info;
  mach_timebase_info(&info);
  frequency = info.denom * 1000ULL / info.numer;

• elif defined(LINUX)

• // extract cpu frequency from /proc/cpuinfo
• float mhz = 0;
• char str[256], *p = NULL;
• int find = 0;
• FILE * fd = fopen("/proc/cpuinfo", "r");
  +
• if (fd == NULL) {
• perror("fopen /proc/cpuinfo");
• } else {
• while (fgets(str, 256, fd)) {
• if (strncmp("cpu MHz", str, sizeof("cpu MHz")-1) == 0) {
• find = 1;
• break;
• }
• }
• fclose(fd);
  +
• if (find) {
• p = str;
• while (*p++ != ':');
• sscanf(p, "%f", &mhz);
• frequency = (uint64_t)mhz;
• ///printf("linux cpu MHz: %f, %lld\n", mhz, frequency);
• } else {
• printf("Warning!!! /proc/cpuinfo cpu MHz unknown\n");
• }

• }
  #endif

  // Fall back to microsecond if the resolution is not high enough.