Re: dlls/kernel32/task.c -- minor improvement

[Gerald Pfeifer]

On Sun, 6 Jan 2008, Alexandre Julliard wrote:
> We don't use C99 features in Wine.

Actually we do.

% egrep -r "^(static )?inline " $WINE_SOURCE/ | wc -l
  2031

"inline" is pretty similar to flexible array members in that both were
not in C90, both are in C99, and both have been GNU extensions before
C99, so I'm not sure why we use one but not the other.
> > That said, if you don't want to take the original patch, can we take
> > the one below?
>
> I don't think that's an improvement, thunks are not really words, they 
> are code.

I know, but in the current code we do have WORD thunks[4] and later on we 
twice relyy on the magic constant 8 which comes from that (4*sizeof WORD).

Honestly, I'd hope my patch makes this code easier to grasp.

It certainly would have helped *me* when first looking at this code! ;-)

Gerald

ChangeLog:
Use 4*sizeof(WORD) instead of the magic constant 8 for THUNKS.thunks,
and explain why we cannot use an open array type THUNKS.thunks[].

Index: dlls/kernel32/task.c
===================================================================
RCS file: /home/wine/wine/dlls/kernel32/task.c,v
retrieving revision 1.2
diff -u -3 -p -r1.2 task.c
--- dlls/kernel32/task.c	13 Oct 2006 10:27:19 -0000	1.2
+++ dlls/kernel32/task.c	6 Jan 2008 12:26:32 -0000
@@ -57,7 +57,10 @@ typedef struct
     WORD  magic;      /* Thunks signature */
     WORD  unused;
     WORD  free;       /* Head of the free list */
-    WORD  thunks[4];  /* Each thunk is 4 words long */
+    WORD  thunks[4];  /* Each thunk is 4 words long, and while we will
+                       * dynamically allocate the whole struct according
+                       * to the actual number of thunks we cannot use the
+                       * thunks[] syntax here because it is not C90. */
 } THUNKS;

#include "poppack.h"
@@ -174,7 +177,7 @@ static void TASK_CreateThunks( HGLOBAL16
     free = pThunk->free;
     for (i = 0; i < count-1; i++)
     {
-        free += 8;  /* Offset of next thunk */
+        free += 4*sizeof(WORD);  /* Offset of next thunk */
         pThunk->thunks[4*i] = free;
     }
     pThunk->thunks[4*i] = 0;  /* Last thunk */
@@ -201,7 +204,8 @@ static SEGPTR TASK_AllocThunk(void)
         sel = pThunk->next;
         if (!sel)  /* Allocate a new segment */
         {
-            sel = GLOBAL_Alloc( GMEM_FIXED, sizeof(THUNKS) + (MIN_THUNKS-1)*8,
+            sel = GLOBAL_Alloc( GMEM_FIXED,
+                                sizeof(THUNKS) + (MIN_THUNKS-1)*4*sizeof(WORD),
                                 pTask->hPDB, WINE_LDT_FLAGS_CODE );
             if (!sel) return (SEGPTR)0;
             TASK_CreateThunks( sel, 0, MIN_THUNKS );