JCXZ            Jump if Register CX is Zero          Flags: Not altered

JCXZ location
JECXZ location  (CPU: 386+)

        Logic   if eCX = 0
                   JMP short location
                endif

    JCXZ/JECXZ differ from other conditional jumps because they test
    the contents of the CX or ECX register for zero, not the flags.
    JCXZ is commonly used to bypass a loop if the counter (CX) is
    zero.

    Note that the target of JCXZ must be within -128 to +127 bytes of
    the next instruction.


    Opcode      Format
    E3 cb       JCXZ rel8
    E3 cb       JECXZ rel8


    Length and timing
    Operands    Bytes   8088    186     286     386     486     Pentium
    dest          2     6/18    5/16    4/8+m   5/9+m   5/8     5/6  NP
    dest          2      -       -       -      5/9+m   5/8     5/6  NP

                       Cycles for:  no jump/jump