TABLE OF CONTENTS timer.device/--background-- timer.device/AbortIO timer.device/AddTime timer.device/CmpTime timer.device/GetSysTime timer.device/ReadEClock timer.device/SubTime timer.device/TR_ADDREQUEST timer.device/TR_GETSYSTIME timer.device/TR_SETSYSTIME timer.device/--background-- timer.device/--background-- TIMER REQUEST A time request is a non standard IO Request. It has an IORequest followed by a timeval structure or an eclockval structure. TIMEVAL A timeval structure consists of two longwords. The first is the number of seconds, the latter is the fractional number of microseconds. The microseconds must always be "normalized" e.g. the longword must be between 0 and one million. ECLOCKVAL A eclockval structure consists of two longwords. The first is the high order 32 bits of a 64 bit number and the second is the the low order 32 bits. The 64 bit number is a count of "E" clock ticks. The "E" clock frequency is related to the master clock frequency of the machine and can be determined by calling the ReadEClock() library like call. UNITS The timer contains five units -- two designed to accuratly measure short intervals, one that has little system overhead and is very stable over time, and two that work like an alarm clock. UNIT_MICROHZ This unit uses the programmable timers in the 8520s to keep track of its time. It has precision down to about 2 microseconds, but will drift as system load increases. The accuracy of this unit is the same as that of the master clock of the machine. This unit uses a timeval in its timerequest. UNIT_VBLANK This unit uses a strobe from the power supply to keep track of its time or the "E" clock on machines without power supply strobes. It is very stable over time, but only has a resolution of that of the vertical blank interrupt. This unit is very cheap to use, and should be used by those who are waiting for long periods of time (typically 1/2 second or more). This unit uses a timeval in its timerequest. UNIT_ECLOCK This unit is exacly the same as UNIT_MICROHZ except that it uses an eclockval instead of a timeval in its timerequest. UNIT_WAITUNTIL This unit waits until the systime is greater than or equal to the time in the timeval in the timerequest. This unit has the same resolution and accuracy as that of UNIT_VBLANK. UNIT_WAITECLOCK This unit waits until the E-Clock value as returned by ReadEClock() is greater than or equal to the eclockval in the timerequest. This unit has the same resolution and accuracy as that of UNIT_ECLOCK. LIBRARY In addition to the normal device calls, the timer also supports several direct, library like calls. BUGS In the V1.2/V1.3 release, the timer device has problems with very short time requests. When one of these is made, other timer requests may be finished inaccurately. A side effect is that AmigaDOS requests such as "Delay(0);" or "WaitForChar(x,0);" are unreliable. timer.device/AbortIO timer.device/AbortIO NAME AbortIO -- Remove an existing timer request. SYNOPSIS error = AbortIO( timerequest ) D0 A1 LONG AbortIO( struct timerequest * ); FUNCTION This is an exec.library call. This routine removes a timerquest from the timer. It runs in the context of the caller. INPUTS timerequest - the timer request to be aborted RETURNS 0 if the request was aborted, io_Error will also be set to IOERR_ABORTED. -1 otherwise NOTES This function may be called from interrupts. SEE ALSO exec.library/AbortIO() BUGS timer.device/AddTime timer.device/AddTime NAME AddTime -- Add one time request to another. SYNOPSIS AddTime( Dest, Source ) A0 A1 void AddTime( struct timeval *, struct timeval *); FUNCTION This routine adds one timeval structure to another. The results are stored in the destination (Dest + Source -> Dest) A0 and A1 will be left unchanged INPUTS Dest, Source -- pointers to timeval structures. NOTES This function may be called from interrupts. SEE ALSO timer.device/CmpTime(), timer.device/SubTime() BUGS timer.device/CmpTime timer.device/CmpTime NAME CmpTime -- Compare two timeval structures. SYNOPSIS result = CmpTime( Dest, Source ) D0 A0 A1 LONG CmpTime( struct timeval *, struct timeval *); FUNCTION This routine compares timeval structures A0 and A1 will be left unchanged INPUTS Dest, Source -- pointers to timeval structures. RESULTS result will be 0 if Dest has same time as source -1 if Dest has more time than source +1 if Dest has less time than source NOTES This function may be called from interrupts. SEE ALSO timer.device/AddTime(), timer.device/SubTime() BUGS Older version of this document had the sense of the return codes wrong; the code hasn't changed but the document has. timer.device/GetSysTime timer.device/GetSysTime NAME GetSysTime -- Get the system time. (V36) SYNOPSIS GetSysTime( Dest ) A0 void GetSysTime( struct timeval * ); FUNCTION Ask the system what time it is. The system time starts off at zero at power on, but may be initialized via the TR_SETSYSTIME timer.device command. System time is monotonocally increasing and guarenteed to be unique (except when the system time is set back). A0 will be left unchanged. This function is less expensive to use than the TR_GETSYSTIME IORequest. INPUTS Dest -- pointer to a timeval structure to hold the system time. RESULTS Dest -- the timeval structure will contain the system time. NOTES This function may be called from interrupts. SEE ALSO timer.device/TR_GETSYSTIME, timer.device/TR_SETSYSTIME, BUGS timer.device/ReadEClock timer.device/ReadEClock NAME ReadEClock -- Get the current value of the E-Clock. (V36) SYNOPSIS E_Freq = ReadEClock( Dest ) D0 A0 ULONG ReadEClock ( struct EClockVal * ); FUNCTION This routine calculates the current 64 bit value of the E-Clock and stores it in the destination EClockVal structure. The count rate of the E-Clock is also returned. A0 will be left unchanged This is a low overhead function designed so that very short intervals may be timed. INPUTS Dest -- pointer to an EClockVal structure. RETURNS Dest -- the EClockVal structure will contain the E-Clock time E_Freq -- The count rate of the E-Clock (tics/sec). NOTES This function may be called from interrupts. SEE ALSO BUGS timer.device/SubTime timer.device/SubTime NAME SubTime -- Subtract one time request from another. SYNOPSIS SubTime( Dest, Source ) A0 A1 void SubTime( struct timeval *, struct timeval *); FUNCTION This routine subtracts one timeval structure from another. The results are stored in the destination (Dest - Source -> Dest) A0 and A1 will be left unchanged INPUTS Dest, Source -- pointers to timeval structures. NOTES This function may be called from interrupts. SEE ALSO timer.device/AddTime(), timer.device/CmpTime() BUGS timer.device/TR_ADDREQUEST timer.device/TR_ADDREQUEST NAME TR_ADDREQUEST -- Submit a request to wait a period of time. FUNCTION Ask the timer to wait a specified amount of time before replying the timerequest. The message may be forced to finish early with an AbortIO()/WaitIO() pair. TIMER REQUEST io_Message mn_ReplyPort initialized io_Device preset by timer in OpenDevice io_Unit preset by timer in OpenDevice io_Command TR_ADDREQUEST io_Flags IOF_QUICK permitted (but ignored) tr_time a timeval structure specifying how long the device will wait before replying RESULTS tr_time will be zeroed NOTES This function may be called from interrupts. Previous to 2.0, the tr_time field was documented as containing junk when the timerequest was returned. SEE ALSO timer.device/AbortIO(), timer.device/TimeDelay(), BUGS timer.device/TR_GETSYSTIME timer.device/TR_GETSYSTIME NAME TR_GETSYSTIME -- get the system time. FUNCTION Ask the system what time it is. The system time starts off at zero at power on, but may be initialized via the TR_SETSYSTIME call. System time is monotonically increasing, and guaranteed to be unique (except when the system time is set backwards). TIMER REQUEST io_Message mn_ReplyPort initialized io_Device preset by timer in OpenDevice io_Unit preset by timer in OpenDevice io_Command TR_GETSYSTIME io_Flags IOF_QUICK permitted RESULTS tr_time a timeval structure with the current system time NOTES This function may be called from interrupts. SEE ALSO timer.device/TR_SETSYSTIME, timer.device/GetSysTime(), BUGS timer.device/TR_SETSYSTIME timer.device/TR_SETSYSTIME NAME TR_SETSYSTIME -- Set the system time. FUNCTION Set the system idea of what time it is. The system starts out at time "zero" so it is safe to set it forward to the real time. However, care should be taken when setting the time backwards. System time is generally expected to monotonically increasing. TIMER REQUEST io_Message mn_ReplyPort initialized io_Device preset by timer in OpenDevice io_Unit preset by timer in OpenDevice io_Command TR_GETSYSTIME io_Flags IOF_QUICK permitted tr_time a timeval structure with the current system time RESULTS tr_time will contain junk NOTES This function may be called from interrupts. SEE ALSO timer.device/TR_GETSYSTIME, timer.device/GetSysTime(), BUGS .