mstime.c File Reference

The quest for high resolution clocks. More...

#include "ctl/ctldef.h"
#include "ctl/mstime.h"
#include <time.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>

Include dependency graph for mstime.c:

Go to the source code of this file.

Functions
ustime	ctl_ustime (void)
	Get time in microseconds since midnight, January 1, 1970 UTC (mstime/1000000 == time_t) Though this would *seem* to be simple, it's not. You can't separately poll clock() and then time(NULL), because there is an unspecifiable time period between these two invokations due to interrupt, IO and threading. It's very easy to get one time and another confused, and return a past time from a subsequent call.
int	ctl_ustime_print_seconds (char *buff, size_t bufflen, ustime us)
	Concisely format microsecond time as fractions of seconds.
mstime	ctl_mstime (void)
	Get time in milliseconds since midnight, January 1, 1970 UTC (mstime/1000 == time_t) Though this would *seem* to be simple, it's not. You can't separately poll clock() and then time(NULL), because there is an unspecifiable time period between these two invokations due to interrupt, IO and threading. It's very easy to get one time and another confused, and return a past time from a subsequent call.
int	ctl_mstime_print_seconds (char *buff, size_t bufflen, mstime ms)
	Concisely format millisecond time as fractions of seconds.
bool	ctl_mstime_local (struct tm *ptm, mstime ms)
	Convert mstime to C runtime struct tm - LOCAL time.
bool	ctl_mstime_gm (struct tm *ptm, mstime ms)
	Convert mstime to C runtime struct tm - GMT.
int	ctl_mstime_print_time_local (char *buff, size_t bufflen, mstime ms)
	Format milliseconds as date/time.
int	ctl_mstime_print_time_gm (char *buff, size_t bufflen, mstime ms)
	Format milliseconds as date/time.

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Detailed Description

The quest for high resolution clocks.

Author:

David Mace

Definition in file mstime.c.

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Function Documentation

bool ctl_mstime_gm	(	struct tm *	ptm,
		mstime	ms
	)

Convert mstime to C runtime struct tm - GMT.

Parameters:

	ptm	Pointer to struct tm to receive time
	ms	Milliseconds to print

Returns:

True if ptm was filled in CAUTION: C runtime library may not support -times or times in distant future Format: YYYY/MM/DD HH:MM:SS.mmm or 1999/12/31 23:59:59.999

Definition at line 157 of file mstime.c.

References assertobjptr.

{
    time_t time = ms/1000;
    struct tm* ret = gmtime(&time);
    assertobjptr(ptm);
    if( NULL == ret )
    {
        memset(ptm,0,sizeof(*ptm));
        return false;
    }
    *ptm = *ret;
    return true;
}

bool ctl_mstime_local	(	struct tm *	ptm,
		mstime	ms
	)

Convert mstime to C runtime struct tm - LOCAL time.

Parameters:

	ptm	Pointer to struct tm to receive time
	ms	Milliseconds to print

Returns:

True if ptm was filled in CAUTION: C runtime library may not support -times or times in distant future Format: YYYY/MM/DD HH:MM:SS.mmm or 1999/12/31 23:59:59.999

Definition at line 135 of file mstime.c.

References assertobjptr.

{
    time_t time = ms/1000;
    struct tm* ret = localtime(&time);
    assertobjptr(ptm);
    if( NULL == ret )
    {
        memset(ptm,0,sizeof(*ptm));
        return false;
    }
    *ptm = *ret;
    return true;
}

int ctl_mstime_print_seconds	(	char *	buff,
		size_t	bufflen,
		mstime	ms
	)

Concisely format millisecond time as fractions of seconds.

Parameters:

	buff	Buffer to receive text
	bufflen	Length of buff
	ms	Milliseconds to print

Definition at line 121 of file mstime.c.

References assertptr.

{
    assertptr(buff,bufflen);
    return snprintf( buff, bufflen, "%lld.%03lld", ms/1000, ms%1000 );
}

int ctl_mstime_print_time_gm	(	char *	buff,
		size_t	bufflen,
		mstime	ms
	)

Format milliseconds as date/time.

Parameters:

	buff	Buffer to receive text
	bufflen	Length of buff
	ms	Milliseconds to print CAUTION: C runtime library may not support -times or times in distant future Format: YYYY/MM/DD HH:MM:SS.mmm or 1999/12/31 23:59:59.999

Definition at line 197 of file mstime.c.

References assertptr.

{
    time_t time = ms/1000;
    struct tm* tmtime = gmtime(&time);
    assertptr(buff,bufflen);
    if( NULL == tmtime )
        return snprintf( buff, bufflen, "%lld: %s", (long long)ms, strerror(errno) );
    return snprintf( buff, bufflen, "%04d/%02d/%02d %2.2d:%2.2d:%2.2d.%03d GMT", 1900+tmtime->tm_year, 1+tmtime->tm_mon, tmtime->tm_mday, tmtime->tm_hour, tmtime->tm_min, tmtime->tm_sec, (int)(ms%1000) );
}

int ctl_mstime_print_time_local	(	char *	buff,
		size_t	bufflen,
		mstime	ms
	)

Format milliseconds as date/time.

Parameters:

	buff	Buffer to receive text
	bufflen	Length of buff
	ms	Milliseconds to print CAUTION: C runtime library may not support -times or times in distant future Format: YYYY/MM/DD HH:MM:SS.mmm or 1999/12/31 23:59:59.999

Definition at line 179 of file mstime.c.

References assertptr.

{
    time_t time = ms/1000;
    struct tm* tmtime = localtime(&time);
    assertptr(buff,bufflen);
    if( NULL == tmtime )
        return snprintf( buff, bufflen, "%lld: %s", (long long)ms, strerror(errno) );
    return snprintf( buff, bufflen, "%04d/%02d/%02d %2.2d:%2.2d:%2.2d.%03d", 1900+tmtime->tm_year, 1+tmtime->tm_mon, tmtime->tm_mday, tmtime->tm_hour, tmtime->tm_min, tmtime->tm_sec, (int)(ms%1000) );
}

int ctl_ustime_print_seconds	(	char *	buff,
		size_t	bufflen,
		ustime	us
	)

Concisely format microsecond time as fractions of seconds.

Parameters:

	buff	Buffer to receive text
	bufflen	Length of buff
	us	Microseconds to print

Definition at line 65 of file mstime.c.

Referenced by ctl_profiles_dump_averages_sheet().

{
    return snprintf( buff, bufflen, "%lld.%06lld", us/1000000, us%1000000 );
}