void v3_unlock_irqrestore(v3_lock_t lock, addr_t irq_state) {
os_hooks->mutex_unlock_irqrestore((void *)lock,(void*)irq_state);
}
+
+
+int v3_rw_lock_init(v3_rw_lock_t *lock)
+{
+ lock->reader_count=0;
+ return v3_lock_init(&(lock->lock));
+}
+
+void v3_rw_lock_deinit(v3_rw_lock_t *lock)
+{
+ v3_lock_deinit(&(lock->lock));
+ lock->reader_count=0;
+}
+
+void v3_read_lock(v3_rw_lock_t *lock)
+{
+ addr_t flags;
+
+ flags=v3_lock_irqsave(lock->lock);
+ lock->reader_count++;
+ v3_unlock_irqrestore(lock->lock,flags);
+ // readers can come in after us, writers cannot
+}
+void v3_read_unlock(v3_rw_lock_t *lock)
+{
+ addr_t flags;
+
+ flags=v3_lock_irqsave(lock->lock);
+ lock->reader_count--;
+ v3_unlock_irqrestore(lock->lock,flags);
+ // readers can come in after us, and also writers if reader_count==0
+}
+
+void v3_write_lock(v3_rw_lock_t *lock)
+{
+ // a less hideous implementation is possible, of course...
+ while (1) {
+ v3_lock(lock->lock);
+ if (!(lock->reader_count)) {
+ break;
+ }
+ v3_unlock(lock->lock);
+ V3_Yield();
+ }
+ // holding lock now - reader or writer cannot come in after us
+}
+
+addr_t v3_write_lock_irqsave(v3_rw_lock_t *lock)
+{
+ addr_t flags;
+
+ while (1) {
+ flags=v3_lock_irqsave(lock->lock);
+ if (!(lock->reader_count)) {
+ break;
+ }
+ v3_unlock_irqrestore(lock->lock,flags);
+ V3_Yield();
+ }
+ // holding lock now with interrupts off - reader or writer canot come in after us
+ return flags;
+}
+
+void v3_write_unlock(v3_rw_lock_t *lock)
+{
+ // I am already holding this lock
+ v3_unlock(lock->lock);
+ // readers/writers can now come in
+}
+
+void v3_write_unlock_irqrestore(v3_rw_lock_t *lock, addr_t irq_state)
+{
+ // I am already holding this lock with interrupts off
+ v3_unlock_irqrestore(lock->lock,irq_state);
+ // readers/writers can now come in
+}
