lab thread: finish

2 files changed, 57 insertions, 6 deletions

diff --git a/user/uthread.c b/user/uthread.c
index 18b773d..7641d77 100644
--- a/user/uthread.c
+++ b/user/uthread.c
@@ -11,9 +11,30 @@
 #define MAX_THREAD  4
 
 
+// Saved registers for kernel context switches.
+struct context {
+  uint64 ra;
+  uint64 sp;
+
+  // callee-saved
+  uint64 s0;
+  uint64 s1;
+  uint64 s2;
+  uint64 s3;
+  uint64 s4;
+  uint64 s5;
+  uint64 s6;
+  uint64 s7;
+  uint64 s8;
+  uint64 s9;
+  uint64 s10;
+  uint64 s11;
+};
+
 struct thread {
   char       stack[STACK_SIZE]; /* the thread's stack */
   int        state;             /* FREE, RUNNING, RUNNABLE */
+  struct context context;       /* saved registers to switch thru threads */
 };
 struct thread all_thread[MAX_THREAD];
 struct thread *current_thread;
@@ -56,10 +77,8 @@ thread_schedule(void)
     next_thread->state = RUNNING;
     t = current_thread;
     current_thread = next_thread;
-    /* YOUR CODE HERE
-     * Invoke thread_switch to switch from t to next_thread:
-     * thread_switch(??, ??);
-     */
+     // Invoke thread_switch to switch from t to next_thread:
+    thread_switch((uint64)&t->context, (uint64)&next_thread->context);
   } else
     next_thread = 0;
 }
@@ -73,7 +92,11 @@ thread_create(void (*func)())
     if (t->state == FREE) break;
   }
   t->state = RUNNABLE;
-  // YOUR CODE HERE
+  // Set up new context to start executing at func
+  memset(&t->context, 0, sizeof(struct context));
+  t->context.ra = (uint64)func;
+  // stack grows downward, set sp at the highest stack address in out thread
+  t->context.sp = (uint64)t->stack + STACK_SIZE;
 }
 
 void 
diff --git a/user/uthread_switch.S b/user/uthread_switch.S
index 5defb12..19cc400 100644
--- a/user/uthread_switch.S
+++ b/user/uthread_switch.S
@@ -7,5 +7,33 @@
 
 	.globl thread_switch
 thread_switch:
-	/* YOUR CODE HERE */
+        sd ra, 0(a0)
+        sd sp, 8(a0)
+        sd s0, 16(a0)
+        sd s1, 24(a0)
+        sd s2, 32(a0)
+        sd s3, 40(a0)
+        sd s4, 48(a0)
+        sd s5, 56(a0)
+        sd s6, 64(a0)
+        sd s7, 72(a0)
+        sd s8, 80(a0)
+        sd s9, 88(a0)
+        sd s10, 96(a0)
+        sd s11, 104(a0)
+
+        ld ra, 0(a1)
+        ld sp, 8(a1)
+        ld s0, 16(a1)
+        ld s1, 24(a1)
+        ld s2, 32(a1)
+        ld s3, 40(a1)
+        ld s4, 48(a1)
+        ld s5, 56(a1)
+        ld s6, 64(a1)
+        ld s7, 72(a1)
+        ld s8, 80(a1)
+        ld s9, 88(a1)
+        ld s10, 96(a1)
+        ld s11, 104(a1)
 	ret    /* return to ra */