From fc7a44ba7d88bb9b98fd3f4c9919edb48d1001da Mon Sep 17 00:00:00 2001
From: "hyunghwan.chung" <hyunghwan.chung@c9d47f8d-4fed-4a2f-8cad-691f5fbe3904>
Date: Tue, 16 Feb 2016 17:00:10 +0000
Subject: [PATCH] changed to store the stack poitner of the active process
 before context switching. the stored stack pointer is used to restore
 stix->sp when a method return is performed

---
 stix/lib/exec.c | 26 ++++++++++++++++++++------
 stix/lib/stix.h |  4 +++-
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/stix/lib/exec.c b/stix/lib/exec.c
index dc43124..d8963f3 100644
--- a/stix/lib/exec.c
+++ b/stix/lib/exec.c
@@ -432,7 +432,11 @@ static STIX_INLINE int activate_new_method (stix_t* stix, stix_oop_method_t mth)
 	 *
 	 * if no temporaries exist, the initial sp is -1.
 	 */
+#if defined(STIX_USE_PROCSTK)
+	/* ctx->sp will be set further down */
+#else
 	ctx->sp = STIX_SMOOI_TO_OOP(ntmprs - 1);
+#endif
 	ctx->ntmprs = STIX_SMOOI_TO_OOP(ntmprs);
 	ctx->method_or_nargs = (stix_oop_t)mth;
 	/* the 'home' field of a method context is always stix->_nil.
@@ -472,6 +476,14 @@ static STIX_INLINE int activate_new_method (stix_t* stix, stix_oop_method_t mth)
 
 	STIX_ASSERT (stix->sp >= -1);
 
+#if defined(STIX_USE_PROCSTK)
+	/* when process stack is used, the stack pointer in a context
+	 * is a stack pointer of a process before it is activated */
+	ctx->sp = STIX_SMOOI_TO_OOP(stix->sp);
+#else
+	/* do nothing */
+#endif
+
 	/* switch the active context */
 	SWITCH_ACTIVE_CONTEXT (stix, ctx);
 
@@ -3010,6 +3022,13 @@ printf (">>>>>>>>>>>>>>>> METHOD RETURN FROM WITHIN A BLOCK. NON-LOCAL RETURN..
 						stix->active_context->origin->ip = STIX_SMOOI_TO_OOP(STIX_SMOOI_MIN);
 					}
 
+					STIX_ASSERT (STIX_CLASSOF(stix, stix->active_context->origin) == stix->_method_context);
+				#if defined(STIX_USE_PROCSTK)
+					/* restore the stack pointer */
+					stix->sp = STIX_OOP_TO_SMOOI(stix->active_context->origin->sp);
+				#else
+					/* do nothing */
+				#endif
 					SWITCH_ACTIVE_CONTEXT (stix, stix->active_context->origin->sender);
 
 					/* push the return value to the stack of the new active context */
@@ -3026,17 +3045,12 @@ printf (">>>>>>>>>>>>>>>> METHOD RETURN FROM WITHIN A BLOCK. NON-LOCAL RETURN..
 						STIX_ASSERT (stix->active_context == stix->processor->active->initial_context);
 
 #if defined(STIX_DEBUG_EXEC_001)
-printf ("<<<RETURNIGN TO THE INITIAL CONTEXT>>>\n");
+printf ("<<<RETURNIGN TO THE INITIAL CONTEXT>>> TERMINATING SP => %ld\n", (long int)stix->sp);
 #endif
 
-printf ("TERMINATING SP.... %ld\n", (long int)stix->sp);
 
-					#if defined(STIX_USE_PROCSTK)
-						/* TODO: */
-					#else
 						/* the stack contains the final return value so the stack pointer must be 0. */
 						STIX_ASSERT (stix->sp == 0); 
-					#endif
 
 						if (stix->option.trait & STIX_AWAIT_PROCS)
 							terminate_process (stix, stix->processor->active);
diff --git a/stix/lib/stix.h b/stix/lib/stix.h
index 4fcb029..3b2a30a 100644
--- a/stix/lib/stix.h
+++ b/stix/lib/stix.h
@@ -500,7 +500,9 @@ struct stix_context_t
 	/* SmallInteger, instruction pointer */
 	stix_oop_t          ip;
 
-	/* SmallInteger, stack pointer */
+	/* SmallInteger, stack pointer.
+	 * For a method context, this pointer stores the stack pointer
+	 * of the active process before it gets activated. */
 	stix_oop_t          sp;
 
 	/* SmallInteger. Number of temporaries.