Shinichiro Nakamura / Mbed 2 deprecated TestProgramForBugTopic1074

This is for http://mbed.org/forum/bugs-suggestions/topic/1074/

Dependencies:   mbed

Semaphore.h

Committer:
shintamainjp
Date:
2010-09-08
Revision:
0:49c0ef6111e6
Child:
1:70466efca68e

File content as of revision 0:49c0ef6111e6:

#ifndef _SEMAPHORE_H_
#define _SEMAPHORE_H_

/*
 * http://mbed.org/forum/mbed/topic/181/#comment-799
 */

class Semaphore {
public:
    Semaphore(): s(SemFree) {}

    bool take(bool block = true) {
        int oldval;
        do {
            oldval = __ldrex(&s);
        } while ((block && oldval == SemTaken) || __strex(SemTaken, &s) != 0);
        if (!block) {
            __clrex();
        }
        return (oldval == SemFree);
    }

    void release() {
        s = SemFree;
    }

private:
    enum { SemFree, SemTaken };
    int s;
};

#endif