Operating system for a multi-tasking operating environment

• US 5,012,409 A
• Filed: 03/10/1988
• Issued: 04/30/1991
• Est. Priority Date: 03/10/1988
• Status: Expired due to Fees

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Fletcher, Mitchell S., Semma, Richard P.
• Primary Examiner(s): Eng, David Y.
• Application Number:
  US07/166,334
• Time in Patent Office: 1,146 Days
• Field of Search: 364/200 MS File, 364/900 MS File
• US Class Current: 718/103
• CPC Class Codes: G06F 9/4887 involving deadlines, e.g. rate based, periodic

Abstract

A task scheduler system including an array of priority queues for use in a real time multitasking operating system including equation lists, configuration lists, a function library, input and output drivers, user-created task definition lists of major and minor tasks and interrupt handlers. The system includes task scheduling apparatus which, upon the completion of each library function, interrogates the priority queues and finds the highest priority task segment whose requested resource is available and executed, and which executes task segments in the same priority queue in round-robin fashion. The system further includes task creation apparatus and apparatus for maintaining the status of all major tasks in a system in the states of unlocked and done, unlocked and active, unlocked and waiting, locked and active, or locked and waiting. The status maintaining apparatus also includes apparatus for locking tasks into a mode of operation such that the task scheduler will only allow the locked task to execute and the normal state of priority execution is overridden, and waiting apparatus for suspending operation on a task that requires completion of a library function.

Claims

1. A task scheduler system, including an array of priority queues for use in a real time multitasking operating system including equation lists, configuration lists, a function library, input and output drivers, user-created task definition lists of major and minor tasks, including major and minor task elements, and interrupt handlers, initialized to have programmable timer interrupts, comprising:

(a) means for task scheduling according to priority wherein upon the completion of each library function the priority queues are interrogated and the highest priority task segment is found whose requested resource is available and executed and wherein task segments in the same priority queue are executed in round-robin fashion,

and wherein the task scheduling means further includes means for maintaining the status of all major tasks in the system in the states of unlocked and done, unlocked and active, unlocked and waiting, locked and active, or locked and waiting including means for locking tasks into a mode of operation so as to only allow the locked task to execute overriding the normal state of priority execution, and wherein the task scheduling means still further includes waiting means for suspending operation on a task that requires completion of a library function; and

(b) means for task creation responsive to programmable timer interrupts including means for interrogating the task definition lists and means for creating all major and minor task elements from the task definition lists so as to create major and minor tasks which are added to the priority queues.

2. The system of claim 1 wherein the array of priority queues comprise eight queues.

3. The system of claim 1 wherein the number of task definition lists is a maximum of 128.

4. A method of scheduling tasks included in an array of priority queues for use in a real time multitasking operating system, including equation lists, configuration lists, a function library, input and output drivers, user-created task definition lists of major and minor tasks, including major and minor task elements, and interrupt handlers, initialized to have programmable timer interrupts comprising the steps of:

(a) task scheduling according to priority wherein upon the completion of each library function the priority queues are interrogated and the highest priority task segment is found whose requested resource is available and executed and wherein task segments in the same priority queue are executed in round-robin fashion and where the task scheduling further includes the steps of

maintaining the status of all major task in a system of the states of unlocked and done, unlocked and active, unlocked and waiting, locked and active, or locked and waiting including locking tasks into a mode of operation so as to only execute the locked task and override the normal state of priority execution, and waiting for suspending operation on a task that requires completion of a library function; and

(b) creating tasks in response to the programmable timer interrupts including the steps of interrogating the task definition lists and creating all major and minor task elements form the task definition lists so as to create major and minor tasks.

5. The method of claim 4 further including the step of reserving resources for response to the occurrence of a time critical event.