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cpu_time.c
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cpu_time.c
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/*
* cpu_time() returns CPU time in seconds.
*
* It will be safer to do dummy call right after program starts.
* Since cpu_time() is double, it returns with a decimal point.
* It returns 0.0 when error occurs, but is not ordinal.
* It works on gcc/egcs (Sun,Linux,FreeBSD), Turbo C/LSI-C (MS-DOS).
* You can get the latest version at address follows.
* http://www.nn.iij4u.or.jp/~tutimura/c/
* 2002/ 3/11 (C) tutimura@nn.iij4u.or.jp :-) Feel free to use.
*/
/* How to use (not partial compile)
*
* #include "cpu_time.c"
* ...
* main() {
* cpu_time(); <== dummy call
* ...
* printf( "time:%.2f(sec)\n", cpu_time() );
* }
*/
/* How to use (partial compile)
*
* In common headder
* double cpu_time( void );
*/
#ifdef TEST
#include <stdio.h>
#define TEST_MESSAGE(s) printf("by %s\n",s)
#else
#define TEST_MESSAGE(s)
#endif /* TEST */
#ifdef __STDC__
double cpu_time( void );
#endif /* __STDC__ */
#if ( (defined(MSDOS) || defined(__MSDOS__) || defined(LSI_C)) && \
!(defined(unix) || defined(__unix)) )
/* MS-DOS */
#include <time.h>
#if !defined(CLOCKS_PER_SEC) && defined(CLK_TCK)
#define CLOCKS_PER_SEC CLK_TCK
#endif
double cpu_time( void ) {
clock_t t; static clock_t last = (clock_t)-1;
TEST_MESSAGE("clock()");
t = clock();
if (last == (clock_t)-1) last = t;
return (double)(t-last)/CLOCKS_PER_SEC;
}
/* MS-DOS */
#else /* unix */
#include <sys/time.h>
#include <sys/resource.h>
#include <unistd.h>
#ifdef RUSAGE_SELF
/* Sun 5.5, Linux, FreeBSD, DJGPP */
double cpu_time() {
struct rusage tmp;
TEST_MESSAGE("getrusage()");
if ( getrusage( RUSAGE_SELF, &tmp ) ) return 0.0;
return (double)(tmp.ru_utime.tv_sec)
+(double)(tmp.ru_utime.tv_usec)/1000000;
}
/* Sun 5.5, Linux, FreeBSD, DJGPP */
#else
/* Sun 5.3 */
#include <sys/types.h>
#include <sys/times.h>
double cpu_time() {
struct tms tmp;
TEST_MESSAGE("times()");
if ( times( &tmp ) == -1 ) return 0.0;
return (double)(tmp.tms_utime)/CLK_TCK;
}
/* Sun 5.3 */
#endif
#endif /* unix */
#ifdef TEST
int main() {
int i, j, k;
cpu_time(); /* dummy */
for ( i=0; i<25; i++ ) {
for ( j=0; j<30000; j++ ) {
k=j*j*j*j;
}
j=k;
printf( "time:%.4f(sec)\n", cpu_time() );
}
return 0;
}
#endif /* TEST */
/*
* This program calculates, like
* (double) clock()/CLOCKS_PER_SEC
* does in ANSI, but in better way.
*/
/* This works on ...
*
* SUN
* gcc 2.5.8 (SunOS 4.1.3) -- warning getrusage()
* gcc 2.6.3 (SunOS 5.5/5.5.1) -- warning getrusage()
* egcs 1.1.2 (SunOS 5.5/5.5.1)
*
* Linux
* gcc 2.7.2.3 (Linux 2.0/2.2, glibc2.0.7)
* egcs 1.0.3 (Linux 2.0/2.2, glibc2.0.7)
*
* FreeBSD
* gcc 2.7.2.1 (FreeBSD 3.2-RELEASE)
*
* MS-DOS
* DJGPP
* Turbo C 2nd Ver.1.0
* Turbo C++ Ver.2.0
* Turbo C++ Ver.4.0J
* LSI-C86 Ver.3.3c
*/