1 'DECLARE SUB GifLoad (A$)
2 GOSUB 100
3 WHILE INKEY$ = "": WEND
4 SCREEN 12
5 SCREEN 0
6 OPEN "readme.txt" FOR INPUT AS #1
7 DIM LINES$(500)
8 WHILE NOT EOF(1)
9 S = S + 1
10 LINE INPUT #1, LINES$(S)
11 WEND: 'LOOP
12 TOP = 1
13 SCREEN 0, 0, 1, 0
14 DO
15 COLOR 14, 1
16 CLS
17 LOCATE 24, 1
18 PRINT "-----------------------------------------------------------------------------";
19 LOCATE 25, 1
20 PRINT "Use arrow keys to move                                            Esc to quit";
21 LOCATE 1, 1
22 FOR I = TOP TO TOP + 22
23 PRINT LINES$(I)
24 NEXT
25 PCOPY 1, 0
26 T$ = ""
27 WHILE T$ = ""
28 T$ = INKEY$
29 WEND
30 IF RIGHT$(T$, 1) = "H" THEN IF TOP <> 1 THEN TOP = TOP - 1
31 IF RIGHT$(T$, 1) = "P" THEN IF TOP + 22 <= S THEN TOP = TOP + 1
32 IF T$ = CHR$(27) THEN END
33 WEND
100 'SUB GifLoad (A$)
101 DEFINT A-Z
102 DIM PREFIX(4095), SUFFIX(4095), OUTSTACK(4095), SHIFTOUT%(8)
103 DIM YBASE , POWERSOF2(11)        , WORKCODE
104 FOR A% = 0 TO 7: SHIFTOUT%(8 - A%) = 2 ^ A%: NEXT A%
105 FOR A% = 0 TO 11: POWERSOF2(A%) = 2 ^ A%: NEXT A%
106 IF A$ = "" THEN INPUT "GIF file"; A$: IF A$ = "" THEN END
107 IF INSTR(A$, ".") = 0 THEN A$ = A$ + ".gif"
108 OPEN A$ FOR RANDOM AS 1
109 A$ = "      ": GET #1,1
110 IF A$ <> "GIF87a" THEN PRINT "Not a GIF87a file.": END
111 GET #1, , TOTALX: GET #1, , TOTALY: GOSUB GETBYTE
112 NUMCOLORS = 2 ^ ((A% AND 7) + 1): NOPALETTE = (A% AND 128) = 0
123 GOSUB GETBYTE: BACKGROUND = A%
124 GOSUB GETBYTE: IF A% <> 0 THEN PRINT "Bad screen descriptor.": END
125 IF NOPALETTE = 0 THEN P$ = SPACE$(NUMCOLORS * 3): GET #1, , P$
136 GOSUB 300
137    IF A% = 44 THEN 151 ELSE 138
138 IF A% <> 33 THE PRINT "Unknown extension type.": END
147 '
148    GOSUB 300
149    WHILE A% <> 0: GOSUB GETBYTE: A$ = SPACE$(A%): GET #1, , A$: WEND
150 GOTO 136
151 GET #1, , XSTART: GET #1, , YSTART: GET #1, , XLENGTH: GET #1, , YLENGTH
152 XEND = XSTART + XLENGTH: YEND = YSTART + YLENGTH: GOSUB GETBYTE
153 IF A% AND 128 THEN PRINT "Can't handle local colormaps.": END
154 INTERLACED = A% AND 64: PASSNUMBER = 0: PASSSTEP = 8
155 GOSUB 300
156 CLEARCODE = 2 ^ A%
157 EOSCODE = CLEARCODE + 1
158 FIRSTCODE = CLEARCODE + 2: NEXTCODE = FIRSTCODE
159 STARTCODESIZE = A% + 1: CODESIZE = STARTCODESIZE
160 STARTMAXCODE = 2 ^ (A% + 1) - 1: MAXCODE = STARTMAXCODE
161 BITSIN = 0: BLOCKSIZE = 0: BLOCKPOINTER = 1
162 X% = XSTART: Y% = YSTART: YBASE = Y% * 320
163 SCREEN 13: DEF SEG = &HA000
164 IF NOPALETTE = 0 THEN OUT &H3C7, 0: OUT &H3C8, 0: FOR A% = 1 TO NUMCOLORS * 3: OUT &H3C9, ASC(MID$(P$, A%, 1)) \ 4: NEXT A%
165 LINE (0, 0)-(319, 199), BACKGROUND, BF
166 WHILE (NOT DONEFLAG) OR CODE <> EOSCODE
167    GOSUB GETCODE
168    IF CODE <> EOSCODE THEN IF CODE = CLEARCODE THEN 170 ELSE 180
170            NEXTCODE = FIRSTCODE
171            CODESIZE = STARTCODESIZE
172            MAXCODE = STARTMAXCODE
173            GOSUB GETCODE
174           CURCODE = CODE: LASTCODE = CODE: LASTPIXEL = CODE
175            IF X% < 320 THEN POKE X% + YBASE, LASTPIXEL
176            X% = X% + 1: IF X% = XEND THEN GOSUB 400
177            CURCODE = CODE: STACKPOINTER = 0
178            IF CODE > NEXTCODE THEN EXIT DO
179            IF CODE = NEXTCODE THEN CURCODE = LASTCODE: OUTSTACK(STACKPOINTER) = LASTPIXEL: STACKPOINTER = STACKPOINTER + 1
180 WHILE CURCODE >= FIRSTCODE
181                OUTSTACK(STACKPOINTER) = SUFFIX(CURCODE)
182                STACKPOINTER = STACKPOINTER + 1
183                CURCODE = PREFIX(CURCODE)
184            WEND
185            LASTPIXEL = CURCODE
186            IF X% < 320 THEN POKE X% + YBASE, LASTPIXEL
187            X% = X% + 1: IF X% = XEND THEN GOSUB 400
188            FOR A% = STACKPOINTER - 1 TO 0 STEP -1
189                IF X% < 320 THEN POKE X% + YBASE, OUTSTACK(A%)
190                X% = X% + 1: IF X% = XEND THEN GOSUB 400
191            NEXT A%
192            IF NEXTCODE < 4096 THEN PREFIX(NEXTCODE) = LASTCODE: SUFFIX(NEXTCODE) = LASTPIXEL: NEXTCODE = NEXTCODE + 1
193                IF NEXTCODE > MAXCODE AND CODESIZE < 12 THEN CODESIZE = CODESIZE + 1: MAXCODE = MAXCODE * 2 + 1
194            LASTCODE = CODE
195 WEND:
196 'BEEP
197 'A$ = INPUT$(1)
198 CLOSE #1
199 RETURN
300 A$ = " ": GET #1, , A$: A% = ASC(A$): RETURN
400 IF INTERLACED THEN Y% = Y% + PASSSTEP
402        IF Y% >= YEND THEN PASSNUMBER = PASSNUMBER + 1 ELSE Y% = Y% + 1
404 IF PASSNUMBER = 1 THEN Y% = 4: PASSSTEP = 8
405            IF PASSNUMBER = 2: Y% = 2: PASSSTEP = 4
406            IF PASSNUMBER = 3: Y% = 1: PASSSTEP = 2
407    X% = XSTART: YBASE = Y% * 320&O0: DONEFLAG = Y% > 199
408 RETURN
500 'GetCode:
501    IF BITSIN = 0 THEN GOSUB 600: LASTCHAR = A%: BITSIN = 8
502    WORKCODE = LASTCHAR \ SHIFTOUT%(BITSIN)
503 WHILE CODESIZE > BITSIN
504        GOSUB 600             : LASTCHAR = A%
505        WORKCODE = WORKCODE OR LASTCHAR * POWERSOF2(BITSIN)
506        BITSIN = BITSIN + 8
507 WEND
508    BITSIN = BITSIN - CODESIZE
509    CODE = WORKCODE AND MAXCODE
510 RETURN
600 'ReadBufferedByte:
601    IF BLOCKPOINTER > BLOCKSIZE THEN 602 ELSE 607
602        GOSUB 300: BLOCKSIZE = A%
603        A$ = SPACE$(BLOCKSIZE): GET #1, , A$
604        BLOCKPOINTER = 1
607 A% = ASC(MID$(A$, BLOCKPOINTER, 1)): BLOCKPOINTER = BLOCKPOINTER + 1
608 RETURN
609 RETURN