AX_CPU_FREQ: new submission to detect the cpu frequency

1 files changed, 93 insertions, 0 deletions

diff --git a/m4/ax_cpu_freq.m4 b/m4/ax_cpu_freq.m4
new file mode 100644
index 0000000..98de465
--- /dev/null
+++ b/m4/ax_cpu_freq.m4
@@ -0,0 +1,93 @@
+##### http://autoconf-archive.cryp.to/ax_cpu_freq.html
+#
+# SYNOPSIS
+#
+#   AX_CPU_FREQ
+#
+# DESCRIPTION
+#
+#   Compute the CPU frequency and define CPU_FREQ accordingly.
+#
+# LAST MODIFICATION
+#
+#   2007-11-28
+#
+# COPYLEFT
+#
+#   Copyright (c) 2007 Christophe Tournayre <turn3r@users.sourceforge.net>
+#
+#   Copying and distribution of this file, with or without
+#   modification, are permitted in any medium without royalty provided
+#   the copyright notice and this notice are preserved.
+
+AC_DEFUN([AX_CPU_FREQ],
+[AC_REQUIRE([AC_PROG_CC])
+ AC_LANG_PUSH([C++])
+ AC_CACHE_CHECK(your cpu frequency, ax_cpu_freq,
+ [AC_RUN_IFELSE([AC_LANG_PROGRAM([
+#include <iostream>
+#include <sys/time.h>
+#include <fstream>
+using namespace std;
+
+static __inline__ unsigned long long int rdtsc()
+{
+  unsigned long long int x;
+  __asm__ volatile (".byte 0x0f, 0x31":"=A" (x));
+  return x;
+}
+
+static float estimate_MHz(long sleeptime = 250000)
+{
+  struct timezone tz;
+  struct timeval tvstart, tvstop;
+  unsigned long long int cycles[[2]];
+  float microseconds;
+  double freq = 1.0f;
+
+  memset(&tz, 0, sizeof(tz));
+
+  gettimeofday(&tvstart, &tz);
+  cycles[[0]] = rdtsc();
+  gettimeofday(&tvstart, &tz);
+
+  usleep(sleeptime);
+
+  gettimeofday(&tvstop, &tz);
+  cycles[[1]] = rdtsc();
+  gettimeofday(&tvstop, &tz);
+
+  microseconds = (tvstop.tv_sec - tvstart.tv_sec) * 1000000 +
+    (tvstop.tv_usec - tvstart.tv_usec);
+
+  return (float) (cycles[[1]] - cycles[[0]]) / (microseconds / freq);
+}
+
+static float average_MHz(int tries = 2)
+{
+  float frequency = 0;
+
+  for (int i = 1; i <= tries; i++)
+    frequency += estimate_MHz(i * 150000);
+
+  if (tries > 0)
+    return frequency / (float) tries;
+  else
+    return 0;
+}
+], [
+    ofstream of("conftest_cpufreq");
+    if(of.is_open())
+      of << average_MHz();
+    else
+      return 1;
+
+    of.close()
+])],
+     [ax_cpu_freq=`cat conftest_cpufreq`; rm -f conftest_cpufreq],
+     [ax_cpu_freq=unknow; rm -f conftest_cpufreq]
+ )])
+AC_LANG_POP([C++])
+
+  AC_DEFINE_UNQUOTED([CPU_FREQ], ${ax_cpu_freq}, [The cpu frequency (in MHz)])
+])