SUBROUTINE FLEA
C
C	THIS SUBROUTINE CONTROLS THE ACTIONS OF A FLEA. THE FLEA DROPS
C	STRAIGHT DOWN AND RANDOMLY LEAVES BEHIND MUSHROOMS AT EVERY
C	THIRD LOCATION.
C
      IMPLICIT INTEGER(A - Z)
      PARAMETER MAXCNT = 24
C SCREEN BOUNDARIES
      PARAMETER LMAR = 2, RMAR = 30, TMAR = 2, BMAR = 23, GMAR = 18
C DIRECTIONALS
      PARAMETER HALT = 0, UP = 1, DOWN = 2, LEFT = 4, RIGHT = 8
      PARAMETER UPL = 10, UPR = 9, DOWNL = 12, DOWNR = 11
C DISPLAYABLE CHARACTERS
	PARAMETER GUNCHR="166, CBODY="140, MSHCHR="146, BULCHR="170
	PARAMETER SPICHR="173, FLECHR="175, SCOCHR="142, PSNCHR="052
	PARAMETER CLHEAD="074, CRHEAD="076, CDHEAD="126
	PARAMETER SHFIN="17, SHFOUT="16, SPACE="40
C QIO FUNCTION CODES
	PARAMETER IOATA="1410, IOWVB="11000, SFSMC="2440
C
      INTEGER*4SCORE, FRESCO, TIMER, SEED, FLETIM, SPITIM, SCOTIM, CNTTI
     *M
      DIMENSION PRL(6), CX(MAXCNT, 12), CY(MAXCNT, 12)
      DIMENSION CLEN(MAXCNT), CDIR(MAXCNT), CRISE(MAXCNT), CBOT(MAXCNT)
      BYTE CNTBRD(BMAR, RMAR), MSHBRD(BMAR, RMAR), PSNBRD(BMAR, RMAR)
      COMMON/DIRCOM/DIRCOD, FIRCOD
      COMMON/CNTCOM/PRL, SCORE, TIMER, SEED, CX, CY, CLEN, CDIR, CRISE, 
     *CBOT, GUNX, GUNY, FRESCO, CNTBRD, MSHBRD, PSNBRD, BULACT, BULX, BU
     *LY, FLETIM, FLEACT, FLEX, FLEY, SPITIM, SPIACT, SPIX, SPIY, SPILR,
     * SCOTIM, SCOACT, SCOX, SCOY, SCODIR, GUNCNT, CNTTIM, BOARD, CNTWAV
C
C	VT100 DISPLAY CONTROL PARAMETER DEFINITIONS
C
CCURSOR POSITION REPORT
CCURSOR UP
CCURSOR DOWN
CCURSOR FORWARD
CCURSOR BACK
CDOUBLE WIDTH LINE
      PARAMETER CUP = 1, CUU = 2, CUD = 3, CUF = 4, CUB = 5, DECDWL = 6,
     * DECDHL = 7, DECRC = 8, DECSC = 9, DECSWL = 10, ED = 11, EL = 12, 
     *SGR = 13, NEL = 14, SCS = 15, SM = 16, RM = 17, ANSI = 18, CPP=19
      REAL X, RAN
C
C	GENERATE RANDOM NUMBER.
C
      X = RAN(SEED)
CITMP IS IN RANGE 0-1
      ITMP = X*2
      IF (.NOT.(ITMP .EQ. 1)) GOTO 2000
CRETURN WITHOUT MOTION HALF THE TIME
        RETURN
2000  CONTINUE
      X = RAN(SEED)
CITMP IS IN RANGE 0-4
      ITMP = X*5
C
C	DROP MUSHROOM 20% OF THE TIME IF ABOVE PLAYER'S ZONE,
C	AND 40% OF THE TIME IF IN HIS ZONE.
C
      IF (.NOT.(ITMP .EQ. 0.AND.FLEX .LT. BMAR)) GOTO 2020
CSET MUSHROOM BOARD
        MSHBRD(FLEX, FLEY) = 4
        IF (.NOT.(PSNBRD(FLEX, FLEY) .EQ. 1)) GOTO 2040
CALREADY POISON MUSHROOM HERE
          CALL UVT100(CPP, FLEX, FLEY, PSNCHR)
          GOTO 2050
2040    CONTINUE
CELSE DISPLAY MUSHROOM
        CALL UVT100(CPP, FLEX, FLEY, MSHCHR)
2050    CONTINUE
        GOTO 2030
2020  CONTINUE
      IF (.NOT.(ITMP .EQ. 1.AND.FLEX .LT. BMAR.AND.FLEX .GT. GMAR)) GOTO
     * 2060
CSET MUSHROOM BOARD
        MSHBRD(FLEX, FLEY) = 4
        CALL UVT100(CPP, FLEX, FLEY, MSHCHR)
        GOTO 2030
2060  CONTINUE
CREDISPLAY WHAT WAS HERE BEFORE...
        IF (.NOT.(MSHBRD(FLEX, FLEY) .EQ. 0)) GOTO 2080
CSPACE
          CALL UVT100(CPP, FLEX, FLEY, SPACE)
          GOTO 2090
2080    CONTINUE
        IF (.NOT.(PSNBRD(FLEX, FLEY) .EQ. 0)) GOTO 2100
CMUSHROOM
          CALL UVT100(CPP, FLEX, FLEY, MSHCHR)
          GOTO 2090
2100    CONTINUE
CPOISON MUSHROOM
        CALL UVT100(CPP, FLEX, FLEY, PSNCHR)
2090    CONTINUE
2030  CONTINUE
CDISPLAY CHARACTER ON SCREEN
CDROP FLEA ONE ROW
      FLEX = FLEX + 1
      IF (.NOT.(FLEX .GT. BMAR)) GOTO 2120
CDISAPPEAR IF AT BOTTOM OF SCREEN
        FLEACT = 0
        ICOUNT = 0
        DO 2140 I = GMAR, BMAR
CIF LESS THAN FIVE MUSHROOMS IN PLAYER
          DO 2160 J = LMAR, RMAR
CZONE, NEXT FLEA WILL APPEAR IN 20
            IF (.NOT.(MSHBRD(I, J) .GT. 0)) GOTO 2180
CCYCLES, ELSE IN 200 CYCLES.
              ICOUNT = ICOUNT + 1
2180        CONTINUE
2160      CONTINUE
2140    CONTINUE
        IF (.NOT.(ICOUNT .LT. 5)) GOTO 2200
          FLETIM = TIMER + 20
          GOTO 2210
2200    CONTINUE
          FLETIM = TIMER + 200
2210    CONTINUE
        RETURN
2120  CONTINUE
CDISPLAY FLEA AT NEW LOCATION
      CALL UVT100(CPP, FLEX, FLEY, FLECHR)
      RETURN
      END