JPH04137142A - Timer control system - Google Patents

Abstract

PURPOSE:To reduce the error by only updating the absolute time (called reference time) of a clock provided in a prescribed area of a memory at short time intervals to perform the interrupt handling of a timer service routine by fixed- time interruption. CONSTITUTION:Since the interruption handling of a timer service routine 2 is performed by only update of the reference time of a clock 4, its processing time is very short independently of the frequency in timer processing of a task. Therefore, the reference time Ts of the clock can be updated with a relatively high precision. Each of tasks A and B can perform the time control at intervals of an arbitrary short time when the update time interval of the clock 4, namely, the interruption time interval of a timer interruption 1 is sufficiently short; and even if the frequency in timer processing is increased, the check timing of the control time in the task is properly taken in accordance with the length of the time interval of time control to suppress the increase of the error of the control time.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a timer control method for tasks requiring timer processing in a computer.

In order to realize a timer control method in which the size of the time interval of timer processing is not restricted by the number of timer processing in the program, a timer service routine is provided to manage the system reference time so that it can be referenced from tasks.

A task that performs a process that requires timer time control waits for the required time for each process using a comparison time that is the system's standard time plus the timer time, and then compares it to the system's standard time at a predetermined timing during task execution. Compare with the comparison time,
The system is configured so that when the reference time of the system exceeds the comparison time, the requested time is assumed to have come and a predetermined process is performed.

[Industrial application field]

The present invention relates to a timer control method for tasks requiring timer processing in a computer.

In a program that performs time control by calculating the required time by repeating interrupts for a certain period of time, when the number of nine-hour controls increases, the load on interrupt processing when interrupting for a certain period of time increases. The present invention provides a timer control method in which the load on interrupt processing does not increase even if the number of time controls increases.

[Conventional technology]

FIG. 3 is an explanatory diagram of a conventional timer control method.

In Fig. 3, 1 is a timer interrupt for a certain period of time,
Occurs when a certain period of time set in the timer has elapsed.

2 is a timer service routine, which executes timer interrupt processing in response to timer interrupt 1 at fixed time intervals, and checks whether the required time (i.e., timer time) of the 5 tasks has arrived by controlling each task control block TCB. Check the information.

3 is a task control block TCBIL TCB2.3 in which a main task that requires timer processing generates and prepares a child task at each requested time. ..., TCBN, and the required time T for timer processing is included in each control information.
T, ..., TN are set.

Note that the requested time is expressed in a relative time format and specified as an arbitrary multiple of the constant time interval @Tr of the timer interrupt. Moreover, these TCBI, TCB2. ..., TCBN are linked in a chain using pointers and can be referenced in sequence.

FIG. 4 shows the conventional timer service routine 2 in FIG.
FIG. 5 is a timing diagram of timer control according to the conventional method shown in FIG. 3.

Here, TA is the timer interrupt time interval set for timer interrupt l in FIG. 3, and TCBI, TCB2 . ...,
Let each request time T, ,T,...T, of TCBN be T+
=n+ TA , T2 wfi2Ta , -T i+
= n NT A. Note that nl + nt +
"・+"N is an arbitrary integer.

As shown in FIG. 3, the time when the first timer interrupt occurs is T, and the timer service routine 2 is as follows:
First, compare this time Tr with the required time T of TCB 1, and if Ta≧T1, set the execution request information to TCBl, and if TA<T, leave it as is and proceed to the next TCB 2 process. The request time T2 is then referred to. Here too, it is checked whether TA≧T2, and if TA≧T2, the execution request information is sent to TCB2, and if it is lower than T2, it is left as is and the processing moves to the next T.

Thereafter, similar processing is repeated for each TCB up to TCBN, and when the processing of TCBN is completed, the timer service routine 2 sets the timer interrupt time interval TA and ends.

If the interrupt processing time of timer service routine 2 at this time is T, then the tertiary timer interrupt generation time is 2T, +
It becomes T. Due to this second timer interrupt, timer service routine 2 checks the requested time of each TCB as before, but the time used as the comparison standard at this time is 2T.
, is.

Tm is ignored. Therefore, in TCB 1, 2TA≧
T,, in TCB2, 2TA≧T,..., in TCBN, 2T,≧TN is checked, and the TC whose required time has elapsed
Execution request information is sent to B respectively. In this way, the timer interrupt is repeated until the required time of all TCBs has elapsed, and the required time of each TCB is searched and checked in turn.

The search for each TCB by timer service routine 2 is performed by T
Since the interrupt processing is performed using a pointer placed between CBs, the more timer processing is performed, and therefore the more TCBs are processed, the longer the interrupt processing time T becomes.

becomes longer and the comparison reference time nTA and actual time nTa
+ (n 1) Tm becomes large, and when the time interval TA of - fixed-time timer interrupts is made small to perform fine time control, the error becomes large, which is inconvenient.

[Problem to be solved by the invention]

In this way, with conventional timer control methods, when the number of timer processes increases, the load on the timer service routine that handles interrupts increases, and time control over short time intervals is constrained, resulting in a decrease in program performance. was there.

An object of the present invention is to realize a timer control method in which the size of the time interval of timer processing is not restricted by the number of timer processings of a program.

[Means to solve the problem]

In the present invention, the interrupt processing performed by the timer service routine due to a fixed time interrupt is performed by simply updating the absolute time (referred to as reference time) of a clock provided in a predetermined area of memory at short time intervals, and the timer processing within the task is performed. To perform interrupt processing in a short time regardless of the number of interrupts. On the other hand, regarding time control of timer processing within a task, the required time expressed in relative time for each timer processing is expressed in absolute time format (referred to as comparison time) according to the reference time of the clock. Then, each comparison time is compared with the reference time at an appropriate timing while the task is being executed, it is determined whether the comparison time has elapsed, and the corresponding timer processing is performed for the comparison time after the reference time has elapsed. This is how it was done.

FIG. 1 is a diagram explaining the principle of the present invention.

In FIG.

1 is a timer interrupt of a fixed time, and a relatively short time interval is set.

2 is a timer service routine, which updates the reference time of the clock (described later) when a timer interrupt occurs.

4 is a clock that displays a reference time T, which is updated by the timer service routine 2;

5 is a task A, which has comparison times T, , T, □, . . . , TIN for N timer processing.

The reference time T of the clock 4 and each comparison time T are set at a fixed timing.
.

6 is task B and each comparison time T21.6 for 1M timer processing. Tz□, . . . , Tzl, I, and the reference time T of the clock 4 and each comparison time T In comparison, the reference time T is the comparison time T2. Executes timer processing for comparison times exceeding .

[Function] As shown in Fig. 1, the interrupt processing performed by the timer service routine 2 only requires updating the reference time of the clock 4, so the processing time is extremely short regardless of the number of timer processing of the task. I can do it.

Furthermore, it is therefore possible to update the reference time T of the clock with relatively high accuracy.

In addition, each task A and B can perform time control at arbitrary fine time intervals if the update time interval of 2 clocks 4, that is, the interrupt time interval of timer interrupt 1, is sufficiently short, and the number of timer processes can be increased. Even though.

By changing and timing the control time within a task appropriately according to the size of the time control time interval,
It is possible to suppress an increase in control time errors.

〔Example〕

FIG. 2 illustrates a timer service routine and task flow according to an embodiment of the present invention.

In this embodiment, the reference time T of clock 1 is expressed as 9 hours, 1 minute, and 9 seconds on a 24-hour clock, and the time interval of timer interrupt 1 is set to 10 seconds. Timer service routine.

Every time a timer interrupt 1 occurs, the reference time T of this clock 4 is updated in 10 second increments (Δt), and after the update, an interrupt time interval of "10 seconds" is set in a timer (not shown). and exit.

Task A and task B each check the reference time T of the clock 4 at the control time check timing determined within the task.
, and for example, in task A, the comparison time T, , ,
Regarding T, □, ..., TIN, first check whether T11 has timed up (Ts≧T + +), and if it has timed up, control the time of the corresponding timer processing and perform time amplification. If not (T
s < T + +) Check the control time for the next comparison time TI2. Check up to the comparison time TIN, and if there is a comparison time that did not time up, wait for the timing of the next control time check and repeat the same process. I do. Processing ends when all comparison times have timed up. Note that the comparison times in the timer may be grouped according to their fineness, and time-up checks may be performed at different timings.

(Effects of the Invention) According to the present invention, it is possible to execute timer processing with arbitrary precision of time and with little error without using special hardware.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is a flow diagram of an embodiment of the present invention, Fig. 3 is an explanatory diagram of a conventional timer control method, and Fig. 4 is a timer service routine of the conventional method shown in Fig. 3. FIG. 5 is a timing chart of timer control according to the conventional method shown in FIG. 3. In Figure 1. 1: Timer interrupt 2: Timer service routine 4: Clock 5: Task A 6: Task B T, : Reference time T, ~TIs, TzI-Tz, : Comparative time Patent applicant Pfn Co., Ltd.

Claims (1)

[Claims] A timer service routine is provided to manage the system reference time so that it can be referenced from tasks, and a task that performs a process that requires timer time control sets the required time for each process to the system reference time. Wait for the comparison time including the timer time, compare the system reference time and the comparison time at a predetermined timing during task execution,
A timer control method characterized in that when the reference time of the system exceeds the comparison time, the requested time is assumed to have come and predetermined processing is performed.