diff options
author | Vegard Storheil Eriksen <zyp@jvnv.net> | 2012-08-07 16:50:46 +0200 |
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committer | Vegard Storheil Eriksen <zyp@jvnv.net> | 2012-08-07 16:50:46 +0200 |
commit | e586c178073b9a0fee90d5fc8e795d266ebd7b7d (patch) | |
tree | ca9a9c40bab37d5af440c80833755223e2bdd946 /os/mutex.h |
Initial import.
Most sources are split off from suzumebachi project revision 2fc77d2 as is with some path changes. New build rules introduced.
Diffstat (limited to 'os/mutex.h')
-rw-r--r-- | os/mutex.h | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/os/mutex.h b/os/mutex.h new file mode 100644 index 0000000..d12331d --- /dev/null +++ b/os/mutex.h @@ -0,0 +1,42 @@ +#ifndef MUTEX_H +#define MUTEX_H + +class Mutex { + private: + uint8_t locked; + public: + Mutex() : locked(0) {} + Mutex(uint8_t l) : locked(l) {} + + bool trylock() { + uint8_t val; + + // Check if mutex is locked. + asm volatile ("ldrexb %0, [%1]" : "=r" (val) : "r" (&locked)); + if(val) { + return false; + } + + // Try taking the lock. + asm volatile ("strexb %0, %1, [%2]" : "=r" (val) : "r" (1), "r" (&locked)); + if(val) { + return false; + } + + asm volatile("dmb"); + return true; + } + + void lock() { + while(!trylock()) { + Thread::yield(); + } + } + + void unlock() { + asm volatile("dmb"); + locked = 0; + } +}; + +#endif |