From 03b825deba94040867c2e1a61ab935abcba9d675 Mon Sep 17 00:00:00 2001
From: dgp <dgp@users.sourceforge.net>
Date: Tue, 8 Apr 2008 16:12:02 +0000
Subject: backport enhanced comments

---
 generic/tclExecute.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index 1677a78..0003fb2 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -13,7 +13,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclExecute.c,v 1.369 2008/03/18 18:52:07 msofer Exp $
+ * RCS: @(#) $Id: tclExecute.c,v 1.369.2.1 2008/04/08 16:12:02 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -851,23 +851,36 @@ TclFinalizeExecution(void)
 
 /*
  * Auxiliary code to insure that GrowEvaluationStack always returns correctly 
- * aligned memory. This assumes that TCL_ALLOCALIGN is a multiple of the
- * wordsize 'sizeof(Tcl_Obj *)'. 
+ * aligned memory.
+ *
+ * WALLOCALIGN represents the alignment reqs in words, just as TCL_ALLOCALIGN
+ * represents the reqs in bytes. This assumes that TCL_ALLOCALIGN is a
+ * multiple of the wordsize 'sizeof(Tcl_Obj *)'. 
  */
 
 #define WALLOCALIGN \
     (TCL_ALLOCALIGN/sizeof(Tcl_Obj *))
 
+/*
+ * OFFSET computes how many words have to be skipped until the next aligned
+ * word. Note that we are only interested in the low order bits of ptr, so
+ * that any possible information loss in PTR2INT is of no consequence.
+ */
+
 static inline int
 OFFSET(
     void *ptr)
 {
     int mask = TCL_ALLOCALIGN-1;
     int base = PTR2INT(ptr) & mask;
-    return (TCL_ALLOCALIGN - base)/sizeof(Tcl_Obj**);
+    return (TCL_ALLOCALIGN - base)/sizeof(Tcl_Obj *);
 }
 
-#define MEMSTART(markerPtr) \
+/*
+ * Given a marker, compute where the following aligned memory starts. 
+ */
+
+#define MEMSTART(markerPtr)			\
     ((markerPtr) + OFFSET(markerPtr))
 
 
-- 
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