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| -rw-r--r-- | engines/tinsel/background.cpp | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/engines/tinsel/background.cpp b/engines/tinsel/background.cpp index 4f0623df6a..79a8d4a148 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; } |