$CPU 8086          ' make compatible with XT systems
$LIB ALL OFF       ' turn off all PowerBASIC libraries
$ERROR ALL OFF     ' turn off all PowerBASIC error checking
$OPTIMIZE SIZE     ' optimize for smaller code
 $COMPILE UNIT      ' compile to a UNIT (.PBU)
'$COMPILE EXE       ' compile to a UNIT (.PBU)

DEFINT A-Z         ' Required for all numeric functions, forces PB to not
                   ' include floating point in UNIT (makes it smaller)
'/*------------------------------------------------------------------*/
    DECLARE FUNCTION GETSCREEN()  AS STRING
    DECLARE SUB PUTSCREEN(BYVAL X AS STRING)
    DECLARE SUB GETFB(ATTR,CF,CB)
    DECLARE FUNCTION MKTATTR(CF,CB)  AS INTEGER
    DECLARE SUB SAY(BYVAL Row AS INTEGER, BYVAL Col AS INTEGER, BYVAL Text AS STRING, BYVAL Attr AS INTEGER)
    DECLARE FUNCTION GETKEY()  AS STRING
    DECLARE FUNCTION EVAL(BYVAL Expr$,ErrCode AS INTEGER)  AS DOUBLE
    DECLARE SUB EDIT(ROW,COL,ATTR,LTH,F$,RKEY$,OPT$)
'/*------------------------------------------------------------------*/
$CODE SEG "MLIB6"
'/*------------------------------------------------------------------*/
  FUNCTION LINECALC(ROW,COL,ATTR,NBR#) PUBLIC AS DOUBLE
    HSCREEN$ = GETSCREEN
    REDIM HIST$(24)
    IF ROW = 0 AND COL = 0 THEN OPT$ = "WS30"
    IF ROW = 0 THEN ROW = 25
    IF COL = 0 THEN COL = 49
    IF ATTR = 0 THEN
      BATTR = 48
      EATTR = 31
    ELSE
      BATTR = ATTR
      GETFB BATTR,AFC,ABC
      EATTR = MKTATTR(ABC,AFC)
    END IF
    IF NBR# = 0 THEN NBR$ = " " ELSE NBR$ = SETNBR(NBR#)
    SP = 1
    CNT = 1
    MH = ROW-1
    DO
      H$ = TRIM$(NBR$)
      RKEY$ = CHR$(27,13,0,59,0,46)
      OPT$ = "END WS'30'"
      EDIT ROW,COL,ATTR,80,NBR$,RKEY$,OPT$
'/*   --- Display Help? ---*/
      IF RKEY$ = CHR$(0,59) THEN
        DHELP ATTR
        ITERATE
      END IF
'/*   --- Clear the Calculator? ---*/
      IF RKEY$ = CHR$(0,46) THEN
        NBR$ = " "
        TOTAL$ = ""
        SP = 1
        H$ = ""
        CNT = 1
        T# = 0
        PUTSCREEN HSCREEN$
        ITERATE
      END IF
      IF TRIM$(NBR$) <> H$ THEN
        IF RKEY$ = CHR$(13) OR RKEY$ = CHR$(0,60) THEN
          HIST$(CNT) = TRIM$(NBR$) + " = "
          E = 0
          T# = EVAL(NBR$,E)
          IF E > 0 THEN ITERATE
          TOTAL$ = SETNBR(T#)
          NBR$ = TOTAL$
          HIST$(CNT) = HIST$(CNT) + TOTAL$
 '/*      SAY 1,1,"HIST = "+HIST$(CNT),29
 '/*      SAY 2,1,"NBR$ = "+NBR$,29
 '/*      SAY 3,1,"TOTAL$="+TOTAL$,29
 '/*      DHIST ROW,COL,CNT,MH,HIST$(),BATTR
          INCR CNT
          SP = 99
          E = 0
        END IF
      END IF
    LOOP UNTIL RKEY$ = CHR$(27)
    PUTSCREEN HSCREEN$
    FUNCTION = VAL(TOTAL$)
  END FUNCTION
'/*------------------------------------------------------------------*/
  SUB DHELP(ATTR) LOCAL
     HSCREEN$ = GETSCREEN
     SAY  8,14," Clear = AltC, ESC = Exit                            ",ATTR
     SAY  9,14," Use: * / + -    Multiplication, Division, Addition, ",ATTR
     SAY 10,14,"                 and subtraction.                    ",ATTR
     SAY 11,14,"     \ %         Integer Division, Modulus.          ",ATTR
     SAY 12,14,"     ** ^        Raising to the power of.            ",ATTR
     SAY 13,14,"     & | $       Logical AND, OR, and XOR.           ",ATTR
     SAY 14,14,"     =< => <>    Less than or Equal to, Greater than ",ATTR
     SAY 15,14,"                 or Equal to, and Not Equal to.      ",ATTR
     SAY 16,14,"     < > =       Less than, Greater than, and Equal  ",ATTR
     SAY 17,14,"                 to.                                 ",ATTR
     SAY 18,14," Example:        4 + 5 * (4 + 9) / 6                 ",ATTR
     Y$ = GETKEY
     PUTSCREEN HSCREEN$
  END SUB
'/*------------------------------------------------------------------*/
  SUB DHIST(ROW,COL,COUNT,MH,LL$(),ATTR)
'   IF COUNT > MH THEN
'     FOR R = 2 TO COUNT
'       LL$(R-1) = LL$(R)
'     NEXT R
'     COUNT = MH
'   END IF
'   RCNT = COUNT + 1
'   FOR K = 1 TO COUNT
'     RCNT = RCNT - 1
'     T$ = LL$(RCNT) + STRING$(80-LEN(LL$(RCNT)),32)
'     SAY ROW-K,COL,T$,ATTR
'   NEXT K
  END SUB
'/*------------------------------------------------------------------*/
  FUNCTION SETNBR(NBR#) AS STRING
    FUNCTION = RIGHT$(STR$(NBR#),LEN(STR$(NBR#))-1)
  END FUNCTION
'/*------------------------------------------------------------------*/
' $INCLUDE "c:\CODE\MLIB\MLIB.INC"
'  T# = LINECALC(25,1,31,0)
'  SAY 20,1,STR$(T#),29
' Y$ = GETKEY