Aros/Developer/Docs/Devices/Timer

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Purpose[edit]

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]

AddTime()[edit]

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]

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]

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]

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]

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]

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]

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()