update name of code to labcodes

labcodes/lab8/kern/sync/sem.c

@@ -0,0 +1,77 @@
+#include <defs.h>
+#include <wait.h>
+#include <atomic.h>
+#include <kmalloc.h>
+#include <sem.h>
+#include <proc.h>
+#include <sync.h>
+#include <assert.h>
+
+void
+sem_init(semaphore_t *sem, int value) {
+    sem->value = value;
+    wait_queue_init(&(sem->wait_queue));
+}
+
+static __noinline void __up(semaphore_t *sem, uint32_t wait_state) {
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    {
+        wait_t *wait;
+        if ((wait = wait_queue_first(&(sem->wait_queue))) == NULL) {
+            sem->value ++;
+        }
+        else {
+            assert(wait->proc->wait_state == wait_state);
+            wakeup_wait(&(sem->wait_queue), wait, wait_state, 1);
+        }
+    }
+    local_intr_restore(intr_flag);
+}
+
+static __noinline uint32_t __down(semaphore_t *sem, uint32_t wait_state) {
+    bool intr_flag;
+    local_intr_save(intr_flag);
+    if (sem->value > 0) {
+        sem->value --;
+        local_intr_restore(intr_flag);
+        return 0;
+    }
+    wait_t __wait, *wait = &__wait;
+    wait_current_set(&(sem->wait_queue), wait, wait_state);
+    local_intr_restore(intr_flag);
+
+    schedule();
+
+    local_intr_save(intr_flag);
+    wait_current_del(&(sem->wait_queue), wait);
+    local_intr_restore(intr_flag);
+
+    if (wait->wakeup_flags != wait_state) {
+        return wait->wakeup_flags;
+    }
+    return 0;
+}
+
+void
+up(semaphore_t *sem) {
+    __up(sem, WT_KSEM);
+}
+
+void
+down(semaphore_t *sem) {
+    uint32_t flags = __down(sem, WT_KSEM);
+    assert(flags == 0);
+}
+
+bool
+try_down(semaphore_t *sem) {
+    bool intr_flag, ret = 0;
+    local_intr_save(intr_flag);
+    if (sem->value > 0) {
+        sem->value --, ret = 1;
+    }
+    local_intr_restore(intr_flag);
+    return ret;
+}
+