From f2c51bc81d2aa618b29ddbeaae5ac1c5308821f0 Mon Sep 17 00:00:00 2001 From: Alex Auvolat Date: Mon, 9 Feb 2015 17:39:41 +0100 Subject: Reorganize all. --- src/common/mutex.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) create mode 100644 src/common/mutex.c (limited to 'src/common/mutex.c') diff --git a/src/common/mutex.c b/src/common/mutex.c new file mode 100644 index 0000000..cda8049 --- /dev/null +++ b/src/common/mutex.c @@ -0,0 +1,27 @@ +#include + +/* Internal use only. This function is atomic, meaning it cannot be interrupted by a system task switch. */ +static uint32_t atomic_exchange(uint32_t* ptr, uint32_t newval) { + uint32_t r; + asm volatile("xchg (%%ecx), %%eax" : "=a"(r) : "c"(ptr), "a"(newval)); + return r; +} + +void mutex_lock(uint32_t* mutex) { + while (atomic_exchange(mutex, MUTEX_LOCKED) == MUTEX_LOCKED) { + yield(); + } +} + +int mutex_try_lock(uint32_t* mutex) { + if (atomic_exchange(mutex, MUTEX_LOCKED) == MUTEX_LOCKED) { + return 0; + } + return 1; +} + +void mutex_unlock(uint32_t* mutex) { + *mutex = MUTEX_UNLOCKED; +} + +/* vim: set ts=4 sw=4 tw=0 noet :*/ -- cgit v1.2.3