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external/vpc/tier0/cpu_posix.cpp

@@ -0,0 +1,143 @@
+//========= Copyright 1996-2005, Valve Corporation, All rights reserved. ============//
+//
+// Purpose: determine CPU speed under linux
+//
+// $NoKeywords: $
+//=============================================================================//
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <tier0/platform.h>
+#include <errno.h>
+
+#define rdtsc(x) \
+	__asm__ __volatile__ ("rdtsc" : "=A" (x))
+
+class TimeVal
+{
+public:
+	TimeVal() {}
+	TimeVal& operator=(const TimeVal &val) { m_TimeVal = val.m_TimeVal; } 
+	inline double operator-(const TimeVal &left)
+	{
+	  uint64 left_us = (uint64) left.m_TimeVal.tv_sec * 1000000 + left.m_TimeVal.tv_usec;
+	  uint64 right_us = (uint64) m_TimeVal.tv_sec * 1000000 + m_TimeVal.tv_usec;
+	  uint64 diff_us = left_us - right_us;
+	  return diff_us/1000000;
+	}
+
+	timeval m_TimeVal;
+};
+
+// Compute the positive difference between two 64 bit numbers.
+static inline uint64 diff(uint64 v1, uint64 v2)
+{
+  uint64 d = v1 - v2;
+  if (d >= 0) return d; else return -d;
+}
+
+#ifdef OSX
+uint64 GetCPUFreqFromPROC()
+{
+        int mib[2] = {CTL_HW, HW_CPU_FREQ};
+        uint64 frequency = 0;
+        size_t len = sizeof(frequency);
+
+        if (sysctl(mib, 2, &frequency, &len, NULL, 0) == -1)
+                return 0;
+        return frequency;
+}
+#else
+uint64 GetCPUFreqFromPROC()
+{
+    double mhz = 0;
+    char line[1024], *s, search_str[] = "cpu MHz";
+    FILE *fp; 
+    
+    /* open proc/cpuinfo */
+    if ((fp = fopen("/proc/cpuinfo", "r")) == NULL)
+    {
+	return 0;
+    }
+
+    /* ignore all lines until we reach MHz information */
+    while (fgets(line, 1024, fp) != NULL) 
+    { 
+	if (strstr(line, search_str) != NULL) 
+	{
+	    /* ignore all characters in line up to : */
+	    for (s = line; *s && (*s != ':'); ++s);
+	    /* get MHz number */
+	    if (*s && (sscanf(s+1, "%lf", &mhz) == 1)) 
+		break;
+	}
+    }
+
+    if (fp!=NULL) fclose(fp);
+
+    return (uint64)(mhz*1000000);
+}
+#endif
+
+
+uint64 CalculateCPUFreq()
+{
+#ifdef LINUX
+	char const *pFreq = getenv("CPU_MHZ");
+	if ( pFreq )
+	{
+		uint64 retVal = 1000000;
+		return retVal * atoi( pFreq );
+	}
+#endif
+
+  // Compute the period. Loop until we get 3 consecutive periods that
+  // are the same to within a small error. The error is chosen
+  // to be +/- 0.02% on a P-200.
+  const uint64 error = 40000;
+  const int max_iterations = 600;
+  int count;
+  uint64 period, period1 = error * 2, period2 = 0,  period3 = 0;
+
+  for (count = 0; count < max_iterations; count++)
+    {
+      TimeVal start_time, end_time;
+      uint64 start_tsc, end_tsc;
+      gettimeofday (&start_time.m_TimeVal, 0);
+      rdtsc (start_tsc);
+      usleep (5000); // sleep for 5 msec
+      gettimeofday (&end_time.m_TimeVal, 0);
+      rdtsc (end_tsc);
+	
+      period3 = (end_tsc - start_tsc) / (end_time - start_time);
+
+      if (diff (period1, period2) <= error &&
+  	  diff (period2, period3) <= error &&
+   	  diff (period1, period3) <= error)
+ 		break;
+
+      period1 = period2;
+      period2 = period3;
+    }
+
+   if (count == max_iterations)
+    {
+	return GetCPUFreqFromPROC(); // fall back to /proc
+    }
+
+   // Set the period to the average period measured.
+   period = (period1 + period2 + period3) / 3;
+
+   // Some Pentiums have broken TSCs that increment very
+   // slowly or unevenly. 
+   if (period < 10000000)
+    {
+	return GetCPUFreqFromPROC(); // fall back to /proc
+    }
+
+   return period;
+}
+