ref: 75c92428225428c8fde2d015f010e608a0b12f1d
dir: purgatorio/man/10/seconds
.TH SECONDS 10.2
.SH NAME
seconds, ticks, HZ, MS2HZ, MS2TK, TK2MS, TK2SEC \- kernel times and time conversions
.SH SYNOPSIS
.ta \w'\fL#define 'u
.B
long seconds(void)
.PP
.B
ulong ticks(void)
.PP
.EX
#define HZ ...
#define MS2HZ(t) ...
#define TK2SEC(t) ...
#define TK2MS(t) ...
#define MS2TK(m) ...
.EE
.SH DESCRIPTION
.I Seconds
returns the system's idea of the current time as the number of seconds
since the start of the epoch
(00:00:00 GMT, January 1, 1970).
.PP
.I Ticks
returns the number of system-dependent clock ticks since system boot.
.PP
The system clock frequency is platform-dependent.
Several symbolic constants and macro functions are defined by
the file
.B mem.h
to convert between different time units:
.TF TK2SEC(t)
.PD
.TP
.B HZ
The number of clock ticks per second.
.TP
.B MS2HZ
Milliseconds per clock tick.
.TP
.BI TK2SEC( t )
Convert
.I t
clock ticks to seconds and return the result (truncating not rounding).
.TP
.BI TK2MS( t )
Convert
.I t
clock ticks to milliseconds and return the result.
.TP
.BI MS2TK( m )
Convert
.I m
milliseconds to clock ticks and return the result (truncating).
.PP
The functions are often used to calculate delays for timing functions,
for instance:
.IP
.EX
if(atactlrwait(dp->cp, DHmagic, 0, MS2TK(100))){
...
}
.EE