From 151923cca7b86c51a2292b427fbf70e75b05bbe3 Mon Sep 17 00:00:00 2001
From: patthoyts <patthoyts@users.sourceforge.net>
Date: Wed, 1 Aug 2007 13:27:46 +0000
Subject: Abstracted the 'offsetof' to a TclOffset macro as per Tk_Offset to
 permit compilation with MSVC6 and anything else that may not define this
 macro.

---
 ChangeLog            |  6 ++++++
 generic/tclExecute.c |  4 ++--
 generic/tclInt.h     | 14 +++++++++++++-
 generic/tclVar.c     |  4 ++--
 4 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 7a824b6..4270533 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2007-08-01  Pat Thoyts  <patthoyts@users.sourceforge.net>
+
+	* generic/tclInt.h:     Added a TclOffset macro ala Tk_Offset to
+	* generic/tclVar.c:     abstract out 'offsetof' which may not be 
+	* generic/tclExceute.c: defined (eg: msvc6).
+
 2007-08-01  Miguel Sofer  <msofer@users.sf.net>
 
 	* generic/tclVar.c (TclCleanupVar): fix [Bug 1765225], thx Larry
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index 1112c40..fe625a8 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -12,7 +12,7 @@
  * 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 1.307 2007/07/31 17:03:37 msofer Exp $
+ * RCS: @(#) $Id: tclExecute.c,v 1.308 2007/08/01 13:27:47 patthoyts Exp $
  */
 
 #include "tclInt.h"
@@ -181,7 +181,7 @@ static BuiltinFunc tclBuiltinFuncTable[] = {
  */
 
 #define VarHashGetValue(hPtr) \
-    ((Var *) ((char *)hPtr - offsetof(VarInHash, entry)))
+    ((Var *) ((char *)hPtr - TclOffset(VarInHash, entry)))
 
 static inline Var *
 VarHashCreateVar(TclVarHashTable *tablePtr, Tcl_Obj *key, int *newPtr)
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 032a2f6..947d6ec 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -12,7 +12,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclInt.h,v 1.325 2007/07/31 17:03:38 msofer Exp $
+ * RCS: @(#) $Id: tclInt.h,v 1.326 2007/08/01 13:27:47 patthoyts Exp $
  */
 
 #ifndef _TCLINT
@@ -3488,6 +3488,18 @@ MODULE_SCOPE void	TclBNInitBignumFromWideUInt(mp_int *bignum,
 #endif
 
 /*
+ * ----------------------------------------------------------------------
+ * Macro to use to find the offset of a field in a structure.
+ * Computes number of bytes from beginning of structure to a given field.
+ */
+
+#ifdef offsetof
+#define TclOffset(type, field) ((int) offsetof(type, field))
+#else
+#define TclOffset(type, field) ((int) ((char *) &((type *) 0)->field))
+#endif
+
+/*
  *----------------------------------------------------------------
  * Inline version of Tcl_GetCurrentNamespace and Tcl_GetGlobalNamespace
  */
diff --git a/generic/tclVar.c b/generic/tclVar.c
index 967f539..58849c0 100644
--- a/generic/tclVar.c
+++ b/generic/tclVar.c
@@ -16,7 +16,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclVar.c,v 1.146 2007/08/01 12:09:04 msofer Exp $
+ * RCS: @(#) $Id: tclVar.c,v 1.147 2007/08/01 13:27:48 patthoyts Exp $
  */
 
 #include "tclInt.h"
@@ -46,7 +46,7 @@ static inline Var * VarHashNextVar(Tcl_HashSearch *searchPtr);
 static inline void  CleanupVar(Var *varPtr, Var *arrayPtr);
 
 #define VarHashGetValue(hPtr) \
-    ((Var *) ((char *)hPtr - offsetof(VarInHash, entry)))
+    ((Var *) ((char *)hPtr - TclOffset(VarInHash, entry)))
 
 static inline Var *
 VarHashCreateVar(TclVarHashTable *tablePtr, Tcl_Obj *key, int *newPtr)
-- 
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