mirror of https://github.com/ArduPilot/ardupilot
58 lines
1.7 KiB
C++
58 lines
1.7 KiB
C++
#pragma once
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#include "AP_HAL_Namespace.h"
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#include <AP_Common/AP_Common.h>
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#define HAL_SEMAPHORE_BLOCK_FOREVER 0
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class AP_HAL::Semaphore {
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public:
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Semaphore() {}
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// do not allow copying
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Semaphore(const Semaphore &other) = delete;
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Semaphore &operator=(const Semaphore&) = delete;
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virtual bool take(uint32_t timeout_ms) WARN_IF_UNUSED = 0 ;
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virtual bool take_nonblocking() WARN_IF_UNUSED = 0;
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// a varient that blocks forever
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wunused-result"
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virtual void take_blocking() { take(HAL_SEMAPHORE_BLOCK_FOREVER); };
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#pragma GCC diagnostic pop
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virtual bool give() = 0;
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virtual ~Semaphore(void) {}
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};
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/*
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a method to make semaphores less error prone. The WITH_SEMAPHORE()
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macro will block forever for a semaphore, and will automatically
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release the semaphore when it goes out of scope
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Note that we have two types of semaphores. A normal semaphore can
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only be taken once. A recursive semaphore allows for the thread
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holding the semaphore to take it again. It must be released the same
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number of times it is taken.
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The WITH_SEMAPHORE() macro can be used with either type of semaphore
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*/
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class WithSemaphore {
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public:
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WithSemaphore(AP_HAL::Semaphore *mtx, uint32_t line);
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WithSemaphore(AP_HAL::Semaphore &mtx, uint32_t line);
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~WithSemaphore();
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private:
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AP_HAL::Semaphore &_mtx;
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};
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// From: https://stackoverflow.com/questions/19666142/why-is-a-level-of-indirection-needed-for-this-concatenation-macro
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#define WITH_SEMAPHORE( sem ) JOIN( sem, __LINE__, __COUNTER__ )
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#define JOIN( sem, line, counter ) _DO_JOIN( sem, line, counter )
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#define _DO_JOIN( sem, line, counter ) WithSemaphore _getsem ## counter(sem, line)
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