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cbztimer.h
Go to the documentation of this file.00001 // $Id: cbztimer.h,v 1.4 2003/08/07 23:14:01 pnav Exp $ 00002 /* 00003 High-resolution timer code for Linux. 00004 00005 Copyright (C) 2002 by Emery Berger. 00006 Copyright (C) 2002 by The University of Massachusetts. 00007 All rights reserved. 00008 */ 00009 00010 #ifndef CBZ_TIMER_H 00011 #define CBZ_TIMER_H 00012 00013 #include <stdio.h> 00014 #include <limits.h> 00015 #include <time.h> 00016 #include <unistd.h> 00017 #include <fcntl.h> 00018 #include <string.h> 00019 00020 class cbzTimer 00021 { 00022 public: 00023 00024 static void getTime (unsigned long& tlo, unsigned long& thi) { 00025 #ifdef __linux__ 00026 asm volatile ("rdtsc" 00027 : "=a"(tlo), 00028 "=d" (thi)); 00029 #endif 00030 } 00031 00032 00033 static double getFrequency (void) { 00034 static double freq = 0.0; 00035 #ifdef __linux__ 00036 unsigned long LTime0, LTime1, HTime0, HTime1; 00037 if (freq == 0.0) { 00038 00039 // Parse out the CPU frequency from the /proc/cpuinfo file. 00040 00041 enum { MAX_PROCFILE_SIZE = 32768 }; 00042 const char searchStr[] = "cpu MHz : "; 00043 static char line[MAX_PROCFILE_SIZE]; 00044 int fd = open ("/proc/cpuinfo", O_RDONLY); 00045 read (fd, line, MAX_PROCFILE_SIZE); 00046 char * pos = strstr (line, searchStr); 00047 if (pos == NULL) { 00048 00049 // Compute MHz directly. 00050 // Wait for approximately one second. 00051 00052 getTime (LTime0, HTime0); 00053 sleep (1); 00054 getTime (LTime1, HTime1); 00055 00056 freq = (double)(LTime1 - LTime0) + 00057 (double)(UINT_MAX)*(double)(HTime1 - HTime0); 00058 if(LTime1 < LTime0) { freq -= (double)UINT_MAX; } 00059 00060 cout << "THIS IS BAD" << endl; 00061 00062 } else { 00063 // Move the pointer over to the MHz number itself. 00064 pos += strlen(searchStr); 00065 float f; 00066 sscanf (pos, "%f", &f); 00067 freq = ((double) f) * 1000000.0; 00068 } 00069 } 00070 #endif 00071 return freq; 00072 } 00073 00074 00075 cbzTimer (void) 00076 : timeElapsed (0.0), 00077 currentLo(0), 00078 currentHi(0) 00079 {} 00080 00081 void start (void) { 00082 getTime (currentLo, currentHi); 00083 } 00084 00085 void stop (void) { 00086 unsigned long lo, hi; 00087 getTime (lo, hi); 00088 double d = (double) (lo - currentLo) + (double) (UINT_MAX)*(double)(hi - currentHi); 00089 if (lo < currentLo) { 00090 d -= (double) UINT_MAX; 00091 } 00092 timeElapsed += d; 00093 } 00094 00095 operator double (void) { 00096 static double freq = getFrequency (); 00097 return timeElapsed / freq; 00098 } 00099 00100 double time() { 00101 static double freq = getFrequency (); 00102 return timeElapsed / freq; 00103 } 00104 00105 private: 00106 double timeElapsed; 00107 unsigned long currentLo, currentHi; 00108 }; 00109 00110 #endif