Repeats execution of string instructions while CX != 0. After each string operation, CX is decremented and the Zero Flag is tested.

Usage:

	REP MOVSB

The combination of a repeat prefix and a segment override on CPU's before the 386 may result in errors if an interrupt occurs before CX=0. The following code shows code that is susceptible to this and how to avoid it:

again:	rep movs	byte ptr ES:[DI],ES:[SI]	; vulnerable instr.
	jcxz		next				; continue if REP successful
	loop		again				; interrupt goofed count
next:

Modifies flags: