[Scummvm-cvs-logs] scummvm master -> 9c01c385124e80cce56504b57d5fc17b863ee601
fingolfin
max at quendi.de
Wed May 18 14:09:28 CEST 2011
This automated email contains information about 1 new commit which have been
pushed to the 'scummvm' repo located at https://github.com/scummvm/scummvm .
Summary:
9c01c38512 TINSEL: Document pDispList OBJECT linked list 'trick'
Commit: 9c01c385124e80cce56504b57d5fc17b863ee601
https://github.com/scummvm/scummvm/commit/9c01c385124e80cce56504b57d5fc17b863ee601
Author: Max Horn (max at quendi.de)
Date: 2011-05-18T05:06:56-07:00
Commit Message:
TINSEL: Document pDispList OBJECT linked list 'trick'
Changed paths:
engines/tinsel/background.cpp
diff --git a/engines/tinsel/background.cpp b/engines/tinsel/background.cpp
index 4f0623d..79a8d4a 100644
--- a/engines/tinsel/background.cpp
+++ b/engines/tinsel/background.cpp
@@ -162,6 +162,21 @@ OBJECT *GetPlayfieldList(int which) {
pPlayfield = pCurBgnd->fieldArray + which;
// return the display list pointer for this playfield
+ //
+ // HACK: We pretend that pPlayfield is an OBJECT here, by explicitly
+ // casting a pointer to it (resp. to its first member) to an OBJECT
+ // pointer.
+ // Of course it isn't, but its first member is pDispList, an OBJECT
+ // pointer, just like the first member of an OBJECT is pNext, also
+ // an OBJECT pointer. This (classic) trick allows us to use
+ // pPlayfield as a fake anchor element for the linked list of
+ // objects pDispList points to, which in turn simplifies some list
+ // manipulation code. Alas, this is prone to confuse aliasing
+ // analysis in compilers, and also silly developers like myself ;).
+ // So at the very least, I figured we should document this trick
+ // here explicitly.
+ // Personally, I would prefer if we got rid of this trick, e.g. by
+ // introducing an explicit anchor element.
return (OBJECT *)&pPlayfield->pDispList;
}
More information about the Scummvm-git-logs
mailing list