Aros/Developer/Docs/Devices/Timer
Purpose[edit | edit source]
Interrupts and traps are delivered with direct function calls. The different interrupt levels call different interrupt vectors (stored in IntVects[i]). Traps are raised by calling the tc_TrapCode vector of the current task (usually this ends up in an Alert() - the exec equivalent of a kernel panic).
Software interrupts are useful from hardware interrupts if you wish to defer your processing down to a lower level. They can also be used in some special cases of device I/O. The timer.device and audio.device allow software interrupt driven timing and audio output respectively.
Function BeginIO() will perform a timer.device command. It is normally called from within DoIO() and SendIO(). INPUT timereq - The request to process.
API[edit | edit source]
AddTime()[edit | edit source]
void AddTime(
struct timeval * dest,
struct timeval * src );
Function
Add two timeval's together. The result will be the sum dest + src --> dest.
The values of A0 and A1 will not be changed.
Inputs
dest - Destination timeval. src - Source timeval.
Result
dest will contain (src + dest).
Notes
This function can be called from Interrupts.
See also
SubTime() CmpTime()
BeginIO()[edit | edit source]
void BeginIO(
struct timerequest * timereq );
Function
BeginIO() will perform a timer.device command. It is normally called from within DoIO() and SendIO().
INPUT
timereq - The request to process.
Result
The requested message will be processed.
Notes
This function is safe to call from interrupts.
See also
exec.library/AbortIO() exec.library/SendIO() exec.library/DoIO()
CmpTime()[edit | edit source]
LONG CmpTime(
struct timeval * dest,
struct timeval * src );
Function
CmpTime() will compare two timeval's for magnitude, and return which is the larger.
Inputs
dest - Destination timeval src - Source timeval
Result
-1 if dest has more time than src (i.e. dest > src)
0 if dest and src are the same (i.e. dest == src)
+1 if dest has less time than src (i.e. dest < src)
Notes
This function is safe to call from interrupts.
Bugs
The registers A0 and A1 may not be preserved.
See also
AddTime() SubTime()
GetSysTime()[edit | edit source]
void GetSysTime(
struct timeval * dest );
Function
GetSysTime() will fill in the supplied timeval with the current system time.
Inputs
dest - A pointer to the timeval you want the time stored in.
Result
The timeval "dest" will be filled with the current system time.
Notes
This function is safe to call from interrupts.
See also
`TR_GETSYSTIME`_ `TR_SETSYSTIME`_
GetUpTime()[edit | edit source]
void GetUpTime(
struct timeval * dest );
Function
GetUpTime() will fill in the supplied timeval with the current uptime.
Inputs
dest - A pointer to the timeval you want the time stored in.
Result
The timeval "dest" will be filled with the current uptime. This timer cannot be changed by the software and thus can be considered to be a monotonic clock..
Notes
This function is safe to call from interrupts.
See also
`TR_GETSYSTIME`_ `TR_SETSYSTIME`_ `GetSysTime`_
ReadEClock()[edit | edit source]
ULONG ReadEClock(
struct EClockVal * dest );
Function
ReadEClock() reads current value of E-Clock and stores it in the destination EClockVal structure passed as argument. It also returns the frequency of EClock of the system.
This call is supposed to be very fast.
Inputs
dest - Destination EClockVal
Result
The EClock frequency (tics/s)
Notes
This function is safe to call from interrupts.
SubTime()[edit | edit source]
void SubTime(
struct timeval * dest,
struct timeval * src );
Function
SubTime() will subtract the src timeval from the destination timeval, ie "dest - src --> dest".
Inputs
dest - Destination timeval src - Source timeval
Result
The timeval dest will contain the sum (dest - src).
Notes
This function is safe to call from interrupts.
Bugs
May not preserve registers.
See also
AddTime() CmpTime()