LOOP decrements its counter register (either CX or ECX -
if one is not specified explicitly, the BITS setting dictates
which is used) by one, and if the counter does not become zero as a
result of this operation, it jumps to the given label. The jump has
a range of 128 bytes.
LOOPE (or its synonym LOOPZ) adds the additional condition
that it only jumps if the counter is nonzero and the zero flag
is set. Similarly, LOOPNE (and LOOPNZ) jumps only if the
counter is nonzero and the zero flag is clear.