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-rw-r--r--src/common/sched.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/src/common/sched.c b/src/common/sched.c
new file mode 100644
index 0000000..29ea8a8
--- /dev/null
+++ b/src/common/sched.c
@@ -0,0 +1,26 @@
+#include <sched.h>
+
+/* 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;
+}
+
+int mutex_lock(uint32_t* mutex) {
+ while (atomic_exchange(mutex, MUTEX_LOCKED) == MUTEX_LOCKED) {
+ schedule();
+ }
+ return 0;
+}
+
+int mutex_lockE(uint32_t* mutex) {
+ if (atomic_exchange(mutex, MUTEX_LOCKED) == MUTEX_LOCKED) {
+ return 0;
+ }
+ return 1;
+}
+
+void mutex_unlock(uint32_t* mutex) {
+ *mutex = MUTEX_UNLOCKED;
+}