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54 lines
1.8 KiB
54 lines
1.8 KiB
/* |
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This program is free software: you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation, either version 3 of the License, or |
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(at your option) any later version. |
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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You should have received a copy of the GNU General Public License |
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along with this program. If not, see <http://www.gnu.org/licenses/>. |
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*/ |
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#pragma once |
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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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#include <AP_HAL/Semaphores.h> |
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namespace AP_HAL { |
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class 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) : WithSemaphore(*mtx) { } |
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WithSemaphore(AP_HAL::Semaphore &mtx) : _mtx(mtx) { |
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_mtx.take_blocking(); |
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} |
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~WithSemaphore() { |
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_mtx.give(); |
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} |
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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, __COUNTER__ ) |
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#define JOIN( symbol1, symbol2 ) _DO_JOIN( symbol1, symbol2 ) |
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#define _DO_JOIN( symbol1, symbol2 ) WithSemaphore _getsem ## symbol2(symbol1)
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