provided code

src/threads/switch.h

@@ -0,0 +1,39 @@
+#ifndef THREADS_SWITCH_H
+#define THREADS_SWITCH_H
+
+#ifndef __ASSEMBLER__
+/* switch_thread()'s stack frame. */
+struct switch_threads_frame 
+  {
+    uint32_t edi;               /*  0: Saved %edi. */
+    uint32_t esi;               /*  4: Saved %esi. */
+    uint32_t ebp;               /*  8: Saved %ebp. */
+    uint32_t ebx;               /* 12: Saved %ebx. */
+    void (*eip) (void);         /* 16: Return address. */
+    struct thread *cur;         /* 20: switch_threads()'s CUR argument. */
+    struct thread *next;        /* 24: switch_threads()'s NEXT argument. */
+  };
+
+/* Switches from CUR, which must be the running thread, to NEXT,
+   which must also be running switch_threads(), returning CUR in
+   NEXT's context. */
+struct thread *switch_threads (struct thread *cur, struct thread *next);
+
+/* Stack frame for switch_entry(). */
+struct switch_entry_frame
+  {
+    void (*eip) (void);
+  };
+
+void switch_entry (void);
+
+/* Pops the CUR and NEXT arguments off the stack, for use in
+   initializing threads. */
+void switch_thunk (void);
+#endif
+
+/* Offsets used by switch.S. */
+#define SWITCH_CUR      20
+#define SWITCH_NEXT     24
+
+#endif /* threads/switch.h */