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| | 10 P%=&4000:FORV%=0TO3STEP3:[ | | 10 P%=&4000:FORV%=0TO3STEP3:[ |
| | 20 OPT V% | | 20 OPT V% |
| − | 30 \ Detokenise BASIC tokens
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| − | 40 \ =======================
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| − | 50 \ needs, eg tbase=&70 tptr=&72 if calling from BASIC
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| − | 60 \ eg tbase=&A8 tptr=&AA if calling as a *command
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| − | 70 \
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| − | 80 \ ----------------------------------
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| − | 90 \ TokenInit - Find BASIC token table
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| − | 100 \ ----------------------------------
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| − | 110 \ On entry, BASIC ROM must be paged in
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| − | 120 \ On exit, tbase=>Start of token table
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| − | 130 \ A,Y,tptr corrupted, X preserved
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| − | 140 \
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| − | 150 .TokenInit
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| − | 160 LDY #0:STY tptr:LDA #&80:STA tptr+1 :\ tptr=>ROM start
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| − | 170 .TokInitLp
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| − | 180 LDA #1:CLC:ADC tptr:STA tptr :\ Inc. tptr
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| − | 190 LDA #0:TAY:ADC tptr+1:STA tptr+1
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| − | 200LDA(tptr),Y:CMP #&80:BEQ TokInit2:DEY
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| − | 210 .TokInit2
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| − | 220 INY:LDA (tptr),Y:CMP #ASC"A":BNE TokInitLp :\ Not "A"
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| − | 230 INY:LDA (tptr),Y:CMP #ASC"N":BNE TokInitLp :\ Not "AN"
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| − | 240 INY:LDA (tptr),Y:CMP #ASC"D":BNE TokInitLp :\ Not "AND"
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| − | 250 .TokInitOk
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| − | 260 LDA tptr:STA tbase:LDA tptr+1:STA tbase+1
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| − | 270 RTS
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| − | 280 :
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| − | 290 :
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| − | 300 \ -----------------------------
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| − | 310 \ PrToken - Print a BASIC token
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| − | 320 \ -----------------------------
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| − | 330 \ On entry, A=token byte
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| − | 340 \ BASIC ROM must be paged in
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| − | 350 \ tbase=>Start of token table, set by TokenInit
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| − | 360 \ On exit, A,Y,tptr corrupted, X preserved
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| − | 370 \
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| − | 380 .TokenPrint
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| − | 390 PHA:LDA tbase:STA tptr :\ Point to start token table
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| − | 400 LDA tbase+1:STA tptr+1
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| − | 410 .TokPrLp1
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| − | 420 LDY #&FF
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| − | 430 .TokPrLp2
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| − | 440 INY:LDA (tptr),Y:BPL TokPrLp2 :\ Loop until token byte found
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| − | 450 PLA:CMP (tptr),Y:BEQ TokPrFound :\ Found matching token
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| − | 460 PHA:TYA:BNE TokPrStep :\ Step to next token
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| − | 470 .TokPrLp3
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| − | 480 INY:LDA (tptr),Y:BPL TokPrLp3 :\ Find next token byte
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| − | 490 DEY:DEY
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| − | 500 .TokPrStep
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| − | 510 INY:TYA:SEC:ADC tptr:STA tptr :\ Step past this token string
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| − | 520 LDA #0:ADC tptr+1:STA tptr+1
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| − | 530 BNE TokPrLp1 :\ Loop to keep searching
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| − | 540 .TokPrFound
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| − | 550 TYA:BEQ TokPrNxt:LDY #0 :\ Skip past leading token
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| − | 560 .TokPrLp3
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| − | 570 LDA (tptr),Y:BMI TokPrEnd :\ Token byte, end
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| − | 580 CMP #32:BCC TokPrEnd:JSR OSWRCH :\ Flag byte, end
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| − | 590 .TokPrNxt
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| − | 600 INY:BNE TokPrLp3 :\ Loop back for next character
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| − | 610 .TokPrEnd
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| − | 620 RTS
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| − | 630 ]:NEXT
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| − | 640 CALL TokenInit
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| − | 650 FOR A%=&80 TO 255:PRINT ;A%;": ";:CALL TokenPrint:PRINT:NEXT
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| | </pre> | | </pre> |
| | + | [[User:Lurkio|Lurkio]] ([[User talk:Lurkio|talk]]) 20:52, 9 March 2015 (UTC) |
| | + | |
| | + | The '''P%=''' needs to be ''inside'' the loop, not outside! :) |
| | + | See [http://mdfs.net/Info/Comp/BBC/ProgTips/Detoken DetokenDemo]. |
| | + | |
| | + | [[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 22:19, 9 March 2015 (UTC) |
| | + | |
| | + | Thanks, and oops. |
| | + | [[User:Lurkio|Lurkio]] |
I tried to make a listing (below) out of the code and run it in BeebEm, but it just prints out "128: AND" and then hangs. What am I doing wrong? Apologies if it's something incredibly obvious.
5 tbase=&70:tptr=&72:OSWRCH=&FFEE
10 P%=&4000:FORV%=0TO3STEP3:[
20 OPT V%
Lurkio (talk) 20:52, 9 March 2015 (UTC)
The P%= needs to be inside the loop, not outside! :)
See DetokenDemo.
Jgharston (talk) 22:19, 9 March 2015 (UTC)
Thanks, and oops.
Lurkio
