oops forgot this

lrwl.h

@@ -0,0 +1,63 @@
+#pragma omp
+
+#define LRWL_WRITE_ACTIVE (1UL<<31)
+#define LRWL_MASK (LRWL_WRITE_ACTIVE - 1)
+#define LRWL_MAX_READERS 1024
+
+typedef struct LRWL {
+	_Atomic uint32_t data;
+} LRWL;
+
+static inline void lrwl_read_lock(LRWL *self) {
+	while(1) {
+		uint32_t data = atomic_load(&self->data);
+		
+		if((data & LRWL_WRITE_ACTIVE) || (data & LRWL_MASK) >= LRWL_MAX_READERS) {
+			continue;
+		}
+		
+		if(atomic_compare_exchange_weak(&self->data, &data, data + 1)) {
+			return;
+		}
+	}
+}
+
+static inline void lrwl_read_unlock(LRWL *self) {
+	while(1) {
+		uint32_t data = atomic_load(&self->data);
+		
+		assert((data & LRWL_MASK) > 0);
+		
+		if(atomic_compare_exchange_weak(&self->data, &data, data - 1)) {
+			return;
+		}
+	}
+}
+
+static inline void lrwl_write_lock(LRWL *self) {
+	while(1) {
+		uint32_t data = atomic_load(&self->data);
+		
+		if(data & LRWL_WRITE_ACTIVE) {
+			continue;
+		}
+		
+		if(atomic_compare_exchange_weak(&self->data, &data, data | LRWL_WRITE_ACTIVE)) {
+			while((atomic_load(&self->data) & LRWL_MASK) > 0);
+			
+			return;
+		}
+	}
+}
+
+static inline void lrwl_write_unlock(LRWL *self) {
+	while(1) {
+		uint32_t data = atomic_load(&self->data);
+		
+		assert(data & LRWL_WRITE_ACTIVE);
+		
+		if(atomic_compare_exchange_weak(&self->data, &data, data & ~LRWL_WRITE_ACTIVE)) {
+			return;
+		}
+	}
+}