NAME

seconds, ticks, HZ, MS2HZ, MS2TK, TK2MS, TK2SEC − kernel times and time conversions

SYNOPSIS

longseconds(void);

ulong   ticks(void);

#defineHZ          ...
#defineMS2HZ(t)    ...
#defineTK2SEC(t)   ...
#defineTK2MS(t)    ...
#defineMS2TK(m)    ...

DESCRIPTION

­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). 

­Ticks returns the number of system-dependent clock ticks since system boot. 

The system clock frequency is platform-dependent.  Several symbolic constants and macro functions are defined by the file ­mem.h to convert between different time units:

­HZ The number of clock ticks per second. 

­MS2HZ Milliseconds per clock tick. 

TK2SEC(t) Convert ­t clock ticks to seconds and return the result (truncating not rounding). 

TK2MS(t) Convert ­t clock ticks to milliseconds and return the result. 

MS2TK(m) Convert ­m milliseconds to clock ticks and return the result (truncating). 

The functions are often used to calculate delays for timing functions, for instance:

if(atactlrwait(dp->cp, DHmagic, 0, MS2TK(100))){
...
}

Plan 9  —  June 08, 2000