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1 ;;
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2 ;; ackerman function
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3
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4 ;; procedure name ACK
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5 ;; ACK(X,Y)
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6 ;; == if X=0 then Y+1
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7 ;; else if Y=0 then ACK(X-1,1)
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8 ;; else ACK(X-1, ACK(X,Y-1))
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9
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10 ;; calling sequence
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11 ;;
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12 ;; X on x
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13 ;; Y on y
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14 ;; non compile 11.86 sec on Sun 140
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15 ;; compile 7.54 sec on Sun 140
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16
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17 start cld
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18 ldx #1
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19 ldy #1
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20 jsr ack
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21 brk
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22
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23 ack cpx #0
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24 bne xneqzero
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25 xeqzero iny
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26 tya
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27 rts
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28
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29 xneqzero cpy #0
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30 bne yneqzero
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31 dex ;; x <- x-1
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32 yeqzero ldy #1
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33 jmp ack ;; tail recursion
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34
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35 yneqzero txa
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36 pha
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37 dey ;; y <- y-1
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38 jsr ack ;; ack x,y-1
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39 tay
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40 pla
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41 tax
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42 dex ;; x <- x-1
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43 jmp ack ;; tail recursion
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44
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45 end
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46 ;;
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