1 | # |
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2 | # FIX parsing prototype |
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3 | # Robert D. Cameron Aug. 17, 2011 |
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4 | # (c) All rights reserved. |
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5 | # |
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6 | |
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7 | class Basis_bits(): |
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8 | bit_0 = 0 |
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9 | bit_1 = 0 |
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10 | bit_2 = 0 |
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11 | bit_3 = 0 |
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12 | bit_4 = 0 |
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13 | bit_5 = 0 |
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14 | bit_6 = 0 |
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15 | bit_7 = 0 |
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16 | |
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17 | class Fix_lex(): |
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18 | SOH = 0 |
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19 | Equals = 0 |
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20 | Digit = 0 |
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21 | Zero = 0 |
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22 | |
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23 | class Fix_callout(): |
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24 | Header_end = 0 |
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25 | |
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26 | def Classify_bytes(basis_bits, fix_lex): |
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27 | temp1 = (basis_bits.bit_0 | basis_bits.bit_1) |
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28 | temp2 = (basis_bits.bit_2 | basis_bits.bit_3) |
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29 | temp3 = (temp1 | temp2) |
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30 | temp4 = (basis_bits.bit_4 | basis_bits.bit_5) |
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31 | temp5 = (basis_bits.bit_7 &~ basis_bits.bit_6) |
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32 | temp6 = (temp5 &~ temp4) |
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33 | fix_lex.SOH = (temp6 &~ temp3) |
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34 | temp7 = (basis_bits.bit_2 & basis_bits.bit_3) |
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35 | temp8 = (temp7 &~ temp1) |
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36 | temp9 = (basis_bits.bit_4 & basis_bits.bit_5) |
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37 | temp10 = (temp9 & temp5) |
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38 | fix_lex.Equals = (temp8 & temp10) |
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39 | temp11 = (basis_bits.bit_5 | basis_bits.bit_6) |
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40 | temp12 = (basis_bits.bit_4 & temp11) |
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41 | fix_lex.Digit = (temp8 &~ temp12) |
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42 | temp13 = (basis_bits.bit_6 | basis_bits.bit_7) |
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43 | temp14 = (temp4 | temp13) |
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44 | fix_lex.Zero = (temp8 &~ temp14) |
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45 | |
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46 | def Parse_fields(fix_lex, fix_callout): |
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47 | # Fields must begin with a nonzero digit. |
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48 | allowed_leading_digit = fix_lex.Digit &~ fix_lex.Zero |
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49 | # Assume for now that all SOHs are field separators, not data. |
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50 | # Use negated SOH stream to shift in a 1 at start-of-file. |
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51 | starts = ~pablo.Advance(~fix_lex.SOH) |
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52 | EOF_pos = pablo.Advance(EOF_mask) &~ EOF_mask |
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53 | msg_starts = starts & EOF_mask |
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54 | error1 = EOF_pos &~ starts |
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55 | error2 = msg_starts &~ allowed_leading_digit |
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56 | field_ends = pablo.ScanThru(msg_starts, fix_lex.Digit) |
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57 | error3 = field_ends &~ fix_lex.Equals |
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58 | error = error1 | error2 | error3 |
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59 | if error: |
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60 | error_tracker.NoteError("Potential error in header field", error) |
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61 | fix_callout.Header_end = field_ends |
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62 | |
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63 | def main(basis_bits, fix_lex): |
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64 | Classify_bytes(basis_bits, fix_lex) |
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65 | |
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66 | Parse_fields(fix_lex, fix_callout) |
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67 | |
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68 | |
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