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2474
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1 ***************************************
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2
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3 * Pattern Search
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4
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5 * OTHER MODULES REQUIRED: COMPARE
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6
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7 * ENTRY: X=start of memory to search
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8 * U=end of memory
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9 * Y=start of pattern
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10 * D=size of pattern
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11 * CASEMTCH (a global variable in COMPARE) =0 if A<>a, -1 if A=a
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12
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13 * EXIT: X=address of match if found, unchanged if no match
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14 * CC zero set if match, clear for no-match
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15 * A,B,U,Y preserved
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16
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17
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18 nam Pattern Search
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19 ttl Assembler Library Module
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20
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21
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22 psect PTSEARCH,0,0,0,0,0
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23
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24 * set up stack frame for variables
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25
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26 csect
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27
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28 pattend rmb 2 end of pattern in memory
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29 memend rmb 2 realend-pattern size
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30 patsize rmb 2 saved <D>
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31 memstrt rmb 2 saved <X>
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32 patstrt rmb 2 saved <Y>
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33 realend rmb 2 saved <U>
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34
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35 endsect
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36
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37 PTSEARCH:
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38 pshs d,x,y,u
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39 leas -4,s room for temps
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40 tfr u,d end of memory to check
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41 subd patsize,s end-pattern size
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42 std memend,s where we stop looking
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43 ldd patstrt,s
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44 addd patsize,s
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45 std pattend,s
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46
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47 * loop here looking for a match of the first characters
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48
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49 inmatch
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50 cmpx memend,s raeched end of memory
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51 bhs nomatch
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52 lda ,x+ get char from memory
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53 ldb ,y compare to pattern
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54 lbsr COMPARE compare them
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55 bne inmatch keep looking for inital match
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56
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57 * see if rest of pattern matches
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58
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59 more
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60 tfr x,u save pointer
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61 leay 1,y already matched that one
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62
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63 more1
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64 cmpy pattend,s all chars matched, go home happy
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65 beq match
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66 lda ,x+
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67 ldb ,y+
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68 lbsr COMPARE
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69 beq more1 keep matching
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70 tfr u,x match fails, backup and do more
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71 ldy patstrt,s start of pattern
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72 bra inmatch
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73
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74
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75 nomatch
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76 lda #1 clear zero
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77 bra exit
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78
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79 match
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80 leau -1,u start of match
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81 stu memstrt,s where pattern starts
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82 clra set zero flag=found
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83
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84 exit
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85 leas 4,s clean stack
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86 puls d,x,y,u,pc
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87
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88 endsect
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89
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90 |
