Str_compare PROC

   Compares two null-terminated strings.
   The Zero and Carry flags are affected exactly as they would be by the CMP instruction.

Call args:  ADDR string1,
            ADDR string2

Return arg: ZF=1 CF=0 if string1 = string2
            ZF=0 CF=0 if string1 > string2
            ZF=0 CF=1 if string1 < string2
Example:

.data
string1 BYTE "hello",0
string2 BYTE "hellx",0

.code
       INVOKE Str_compare,
              ADDR string1,
              ADDR string2

       je  equal      ;jump if string1 = string2
       ja  s1_larger  ;jump if string1 > string2
       jb  s1_smaller ;jump if string1 < string2