X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;ds=sidebyside;f=src%2Fthreads%2Fthread.c;h=ae92e1d646dc50d50ce02d26747ca12a8bd82236;hb=d5aab5fcc001efba94a378535746e71a2e9d92f2;hp=b0d5a9138eb6e5a438fda9eabb3ec8e67d1ca519;hpb=d741831b2f9d9a2bb3f1bbb0c56857fa260f6c39;p=pintos-anon

diff --git a/src/threads/thread.c b/src/threads/thread.c
index b0d5a91..ae92e1d 100644
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -118,13 +118,15 @@ thread_print_stats (void)
 
 /* Creates a new kernel thread named NAME with the given initial
    PRIORITY, which executes FUNCTION passing AUX as the argument,
-   and adds it to the ready queue.  If thread_start() has been
-   called, then the new thread may be scheduled before
-   thread_create() returns.  It could even exit before
-   thread_create() returns.  Use a semaphore or some other form
-   of synchronization if you need to ensure ordering.  Returns
-   the thread identifier for the new thread, or TID_ERROR if
-   creation fails.
+   and adds it to the ready queue.  Returns the thread identifier
+   for the new thread, or TID_ERROR if creation fails.
+
+   If thread_start() has been called, then the new thread may be
+   scheduled before thread_create() returns.  It could even exit
+   before thread_create() returns.  Contrariwise, the original
+   thread may run for any amount of time before the new thread is
+   scheduled.  Use a semaphore or some other form of
+   synchronization if you need to ensure ordering.
 
    The code provided sets the new thread's `priority' member to
    PRIORITY, but no actual priority scheduling is implemented.
@@ -271,6 +273,31 @@ thread_yield (void)
   schedule ();
   intr_set_level (old_level);
 }
+
+/* Waits for the thread with the specified TID to terminate.  If
+   TID has already terminated or TID does not refer to an
+   immediate child of the current thread, returns immediately.
+
+   This function will be implemented in problem 1-2.  For now, it
+   does nothing. */
+void
+thread_join (tid_t child_tid UNUSED) 
+{
+}
+
+/* Sets the current thread's priority to NEW_PRIORITY. */
+void
+thread_set_priority (int new_priority) 
+{
+  thread_current ()->priority = new_priority;
+}
+
+/* Returns the current thread's priority. */
+int
+thread_get_priority (void) 
+{
+  return thread_current ()->priority;
+}
 
 /* Idle thread.  Executes when no other thread is ready to run. */
 static void
@@ -285,7 +312,8 @@ idle (void *aux UNUSED)
       thread_block ();
       intr_enable ();
 
-      /* Use CPU `hlt' instruction to wait for interrupt. */
+      /* Use CPU `hlt' instruction to wait for interrupt.
+         See [IA32-v2a] "HLT" and [IA32-v3] 7.7. */
       asm ("hlt");
     }
 }
@@ -311,7 +339,7 @@ running_thread (void)
      down to the start of a page.  Because `struct thread' is
      always at the beginning of a page and the stack pointer is
      somewhere in the middle, this locates the curent thread. */
-  asm ("movl %%esp, %0\n" : "=g" (esp));
+  asm ("mov %0, %%esp" : "=g" (esp));
   return pg_round_down (esp);
 }
 
@@ -376,6 +404,10 @@ next_thread_to_run (void)
    the first time a thread is scheduled it is called by
    switch_entry() (see switch.S).
 
+   It's not safe to call printf() until the thread switch is
+   complete.  In practice that means that printf()s should be
+   added at the end of the function.
+
    After this function and its caller returns, the thread switch
    is complete. */
 void
@@ -407,7 +439,10 @@ schedule_tail (struct thread *prev)
 /* Schedules a new process.  At entry, interrupts must be off and
    the running process's state must have been changed from
    running to some other state.  This function finds another
-   thread to run and switches to it. */
+   thread to run and switches to it.
+
+   It's not safe to call printf() until schedule_tail() has
+   completed. */
 static void
 schedule (void) 
 {