'===========================================================================
' Subject: LINE DRAWING ROUTINE               Date: 04-29-96 (00:00)       
'  Author: Ben McGaughey                      Code: ASIC                   
'  Origin: www.iea.com/~benm                Packet: ASIC.ABC
'===========================================================================
REM Line Drawing program for ASIC 5.00
REM Programmed by Ben McGaughey
REM benm@iea.com
REM http://www.iea.com/~benm/
REM Date: April 29, 1996

   REM X1,Y1,X2,Y2 are the starting and ending points of the line.
   X1@ = 22
   Y1@ = 3

   X2@ = 120
   Y2@ = 155

   SCREEN 13

   XUNIT@ = 0
   YUNIT@ = 0

   VALUE@ = Y1@ * 320
   OFFSET@ = VALUE@ + X1@

   YDIFF@ = Y2@ - Y1@

   IF YDIFF@ < 0 THEN
      YDIFF@ = -1 * YDIFF@
      YUNIT@ = -320
   ELSE
      YUNIT@ = 320
   ENDIF

   XDIFF@ = X2@ - X1@

   IF XDIFF@ < 0 THEN
      XDIFF@ = -1 * XDIFF@
      XUNIT@ = -1
   ELSE
      XUNIT@ = 1
   ENDIF

   DEFSEG = &hexA000

   IF XDIFF@ > YDIFF@ THEN
      LENGTH@ = XDIFF@ + 1
      FOR I@ = 0 TO LENGTH@
            POKE OFFSET@ , 15
            OFFSET@ = OFFSET@ + XUNIT@
            ERTERM@ = ERTERM@ + YDIFF@
            IF ERTERM@ > XDIFF@ THEN
                ERTERM@ = ERTERM@ - XDIFF@
                OFFSET@ = OFFSET@ + YUNIT@
            ENDIF
      NEXT I@
   ELSE

   LENGTH@ = YDIFF@ + 1
   FOR I@ = 0 TO LENGTH@
       POKE OFFSET@ , 15
       OFFSET@ = OFFSET@ + YUNIT@
       ERTERM@ = ERTERM@ + XDIFF@
       IF ERTERM@ > 0 THEN
          ERTERM@ = ERTERM@ - YDIFF@
          OFFSET@ = OFFSET@ + XUNIT@
       ENDIF
   NEXT I@

   ENDIF

   PSET ( Y1@ , X1@ ) , 11
   PSET ( Y2@ , X2@ ) , 11

   W0:
   VALUE0$ = INKEY$
   VALUE1$ = ""
   IF VALUE0$ = VALUE1$ THEN
       VALUE0 = 1
   ELSE
       VALUE0 = 0
   ENDIF
   IF VALUE0 <> 0 THEN
   ENDIF
   IF VALUE0 <> 0 THEN W0:

   SCREEN 0
   WIDTH 80

   END