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2474
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1 **************************************
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2
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3 * Memory move
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4
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5 * NOTE: This routine properly moves overlapping areas of memory.
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6 * Uses fast move algorithm
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7
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8 * ENTRY: X=source data
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9 * Y=destination
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10 * D=count
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11
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12 * EXIT: all registers (except CC) preserved
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13
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14 nam Move Memory
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15 ttl Assembler Library Module
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16
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17
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18
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19 psect MEMMOVE,0,0,0,0,0
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20
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21 MEMMOVE:
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22 pshs d,x,y,u
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23 std -2,s test u
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24 beq exit zero count, exit
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25 tfr y,u use u for dest
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26 tfr d,y count in y
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27 cmpu 2,s compare dest. to source (x)
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28 beq exit same, no need to move
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29 bhi down u>x
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30
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31 up
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32 bitb #1 see if odd number to move
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33 beq up1
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34 lda ,x+ move odd byte
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35 sta ,u+
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36 leay -1,y could be only one
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37 beq exit
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38
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39 up1
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40 ldd ,x++ move 2 bytes
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41 std ,u++
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42 leay -2,y count down
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43 bne up1
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44 bra exit
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45
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46 down
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47 leau d,u u=dest end (count in D)
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48 leax d,x x=source end
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49
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50 bitb #1
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51 beq down2
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52 lda ,-x move odd byte
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53 sta ,-u
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54 leay -1,y could be only one to do
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55 beq exit
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56
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57 down2
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58 ldd ,--x get 2 bytes
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59 std ,--u move them
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60 leay -2,y count down
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61 bne down2
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62
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63 exit
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64 puls d,x,y,u,pc
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65
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66 endsect
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