I think it''s like this:

FOO *Foo;
...

In c:

a = Foo->Bar;

In assembly:

mov a, FOO PTR [Foo].Bar

Completely black slowly, or immediately? I suppose slowly, while a fade is slow... If you put all gammas to 0, won''t the screen go black at once?

To make it easier, why not put those two variables (whatever they were called) in two new variables. ptr is the data type the two display pointers are declared as (probably some redefinition of an int). Look in the correct *.h file:

ptr source, dest;

source = lddsrouceblabla...
dest = destination-variable

In the asm-code, replace the two wrong lines:

mov esi, ddsdSource.lpddsprimary
mov edi, ddsdDest.lpddsprimary

with:

mov esi, source
mov edi, dest

BTW, you should learn some asm. It''s really great when you need some high-speed graphics.