;---------------
;   USAGE      library module, NOT a standalone program
;---------------

; This module provides the routine USAGE_EXIT, which outputs the message
;  USAGE_MSG, of size USAGE_SIZE bytes, to the error console; then exits
;  the program with error code 1.
;
;  USAGE_MSG and USAGE_SIZE must be defined by the user's program!

USAGE_EXIT:
  MOV DX,USAGE_MSG        ; point to the usage message
  MOV CX,USAGE_SIZE       ; load the length of the message
  CALL EWRITE             ; output the message to the error console
BAD_EXIT:
  MOV AL,1                ; 1 code means program was unsuccessful
  JMP EXIT                ; exit back to the operating system