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$FreeBSD: stable/11/share/man/man3/timeradd.3 119893 2003-09-08 19:57:22Z ru $
.Dd August 11, 1999 .Dt TIMERADD 3 .Os .Sh NAME .Nm timeradd , .Nm timersub , .Nm timerclear , .Nm timerisset , .Nm timercmp .Nd operations on timevals .Sh SYNOPSIS n sys/time.h .Ft void .Fn timeradd "struct timeval *a" "struct timeval *b" "struct timeval *res" .Ft void .Fn timersub "struct timeval *a" "struct timeval *b" "struct timeval *res" .Ft void .Fn timerclear "struct timeval *tvp" .Ft int .Fn timerisset "struct timeval *tvp" .Ft int .Fn timercmp "struct timeval *a" "struct timeval *b" CMP .Sh DESCRIPTION These macros are provided for manipulating .Fa timeval structures for use with the .Xr gettimeofday 2 and .Xr settimeofday 2 calls. The structure is defined in n sys/time.h as: d -literal struct timeval { long tv_sec; /* seconds since Jan. 1, 1970 */ long tv_usec; /* and microseconds */ }; .Ed
p .Fn timeradd adds the time information stored in .Fa a to .Fa b and stores the resulting .Vt timeval in .Fa res . The results are simplified such that the value of .Fa res->tv_usec is always less than 1,000,000 (1 second).
p .Fn timersub subtracts the time information stored in .Fa b from .Fa a and stores the resulting .Vt timeval in .Fa res .
p .Fn timerclear initializes .Fa tvp to midnight (0 hour) January 1st, 1970 (the Epoch).
p .Fn timerisset returns true if .Fa tvp is set to any time value other than the Epoch.
p .Fn timercmp compares .Fa a to .Fa b using the comparison operator given in .Fa CMP , and returns the result of that comparison. .Sh SEE ALSO .Xr gettimeofday 2 .Sh HISTORY The .Fn timeradd family of macros were imported from .Nx 1.1 , and appeared in .Fx 2.2.6 .