LOOP instruction fails to loop even though (--cx != 0)

Question

I'm implementing a multiplication algorithm for school, so please no help with the algorithm. I'm using C subroutine conventions, so I don't need to push CX, and the result is returned in DX:AX . I'm using codeview to do the debugging.

At the LOOP line, CX is seen to be 16:

After stepping with F10, I believe it should put me back at the shiftR label. What happens is that CX becomes 0, and I continue to exit the subroutine as is seen in this screenshot:

As well, you can see that the Carry and Overflow flags are set after stepping! I didn't think LOOP could do that? What gives? What am I overlooking?

What if you use F8 instead of F10? – David Wohlferd Mar 28 '16 at 01:21 — David Wohlferd, Mar 28 '16 at 01:21

score 3 · Accepted Answer · edited May 23 '17 at 12:15

3

SOLVED: I jumped the gun. As David Wohlferd mentioned, F8 is step and F10 is next using GDB terminology.

edited May 23 '17 at 12:15

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answered Mar 28 '16 at 01:54

Doug Clark

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LOOP instruction fails to loop even though (--cx != 0)

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