3 ms·
The specification does not explicitly say that, but the clear intention is that REP with CX=0 should be no-op (you get exactly that situation when REP gets inte
by dfox 2y ago
The specification does not explicitly say that, but the clear intention is that REP with CX=0 should be no-op (you get exactly that situation when REP gets interrupted during the last iteration, in that case CX is zero and IP points to the REP, not the following instruction).
- bonzini 2y agoRep movsb copies 64K if CX=0 (that's actually very useful), but memcpy could be implemented as two instructions: jcxz skip rep movsb skip: