Hi I'm a beginner at assembly language and I have a piece of code I'm trying to understand. I understand most of it but I still am not sure what -(A7) or (A7)+ mean. I know An are address registers and so A7 is the last 32 bit address register (coldfire processor). But whats the -/+ before and after? Is it decrementing or incrementing? If so, what is being incremented or decremented? The address registers themselves? e.g. does -(A7) mean A6? Thanks.
-(A7) dereferences and predecrements A7, in C++ this would be *(--A7) (A7)+ dereferences and postincrements A7, in C++ *(A7++). -(A7) decreases the value in A7 by 1, then looks up in memory what is at address A7. So if we have the following memory layout: 0012bcad 41 0012bcae 37 0012bcaf 26 and A7 contains 0012bcae, move.b -(A7),d0 will change A7 to 0012bcad and load 41 into d0. Mirroring that, if A7 contains 0012bcae, move.b (A7)+,d0 will load 37 into d0 and change A7 to 0012bcaf.
