Semaphore mechanism based on [mu] C/OS-II system

Abstract

The invention discloses a semaphore mechanism based on a [mu] C / OS-II system, and the semaphore mechanism protects shared resources, and divides semaphores into a reading mechanism and a writing mechanism. When semaphores are created, attributes such as a read task table, an event waiting table and a semaphore state are distributed to the semaphores. When one read task occupies the semaphore, the priority of the task is stored in the read task table, the occupied state of the semaphore is changed, other tasks which want to read the shared resources still can apply for the read semaphore, and tasks which want to write the shared resources do not apply for the semaphore, so that reading and reading sharing, read-write mutual exclusion and write-write mutual exclusion are realized. And the priority of the tasks in the read task table can be improved to avoid the condition of priority inversion, so that the problems that the overhead is relatively high due to the fact that the tasks are frequently suspended in a mutual exclusion semaphore mechanism in a mu C / OS-II system and a writer waits for a long time in a read / write semaphore mechanism are solved, and the execution efficiency of communication between the tasks is further improved.

Description

technical field [0001] The invention belongs to the technical field of embedded real-time operating systems, and relates to a semaphore mechanism based on μC / OS-II system. Background technique [0002] μC / OS-II is a priority-based preemptive hard real-time kernel, which provides the most basic system services, such as semaphore, mailbox, message queue, memory management, interrupt management, etc. In the real-time kernel, there are often multiple tasks accessing the same shared resource at the same time. In order to prevent the shared resource from being destroyed, μC / OS-II uses a mutual exclusion semaphore to protect it, but for a real-time kernel, the mutual exclusion semaphore The overhead of the implementation mechanism is relatively large, that is, operations such as suspending other tasks. There are two ways for a task to access global variables / competing resources - read / write. If the task is only reading the global variable and does not change the value of the globa...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a kind of semaphore mechanism for protecting shared resources to protect shared resources when using mutual exclusion semaphore mechanism in the real-time operating system kernel μC / OS-II to protect shared resources. Improving the real-time performance of μC / OS-II system

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