1 | ;+ |
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2 | ; @file_comments |
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3 | ; |
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4 | ; |
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5 | ; @categories |
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6 | ; |
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7 | ; |
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8 | ; @param NUM |
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9 | ; |
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10 | ; |
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11 | ; @returns |
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12 | ; |
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13 | ; |
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14 | ; @restrictions |
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15 | ; |
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16 | ; |
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17 | ; @examples |
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18 | ; |
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19 | ; |
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20 | ; @history |
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21 | ; |
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22 | ; |
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23 | ; @version |
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24 | ; $Id$ |
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25 | ;- |
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26 | FUNCTION scan_grib_recstart, num |
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27 | ; |
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28 | compile_opt idl2, strictarrsubs |
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29 | ; |
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30 | |
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31 | infofile = fstat(num) |
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32 | ; minimum size of one record |
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33 | minisize = 8L+28L+4L+4L |
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34 | maxoffset = infofile.size-minisize |
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35 | ; |
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36 | start = 0L |
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37 | offset = 0L |
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38 | previousrecsize = 0L |
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39 | |
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40 | WHILE offset LT maxoffset DO BEGIN |
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41 | ; Every record must begin with 'GRIB'. |
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42 | ; However, their is no rule to define the space between 2 records. |
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43 | ; (1) we try space = previousrecsize MOD 8, because for echam outputs, |
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44 | ; the total size of the records is rounded to modulo 8 |
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45 | addoff = 8 - (previousrecsize MOD 8) |
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46 | offset = offset+addoff |
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47 | IF offset GE maxoffset THEN GOTO, out |
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48 | a = assoc(num, bytarr(4, /nozero), offset) |
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49 | typefile = string(a[0]) |
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50 | IF typefile NE 'GRIB' THEN offset = offset-addoff |
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51 | ; (2) we try space = previousrecsize MOD 120, because for ecmwf |
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52 | ; outputs, the total size of the records is rounded to modulo 120 |
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53 | addoff = 120 - (previousrecsize MOD 120) |
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54 | IF typefile NE 'GRIB' THEN BEGIN |
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55 | offset = offset+addoff |
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56 | IF offset GE maxoffset THEN GOTO, out |
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57 | a = assoc(num, bytarr(4, /nozero), offset) |
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58 | typefile = string(a[0]) |
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59 | IF typefile NE 'GRIB' THEN offset = offset-addoff |
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60 | ENDIF |
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61 | ; (3) we try space = 0 |
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62 | IF typefile NE 'GRIB' THEN BEGIN |
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63 | a = assoc(num, bytarr(4, /nozero), offset) |
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64 | typefile = string(a[0]) |
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65 | ENDIF |
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66 | ; (4) we try any value for space |
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67 | IF typefile NE 'GRIB' THEN BEGIN |
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68 | REPEAT BEGIN |
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69 | CASE 1 OF |
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70 | array_equal((a[0])[3 ], byte('G' )):offset = offset+3 |
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71 | array_equal((a[0])[2:3], byte('GR' )):offset = offset+2 |
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72 | array_equal((a[0])[1:3], byte('GRI')):offset = offset+1 |
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73 | else:offset = offset+4 |
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74 | ENDCASE |
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75 | IF offset GE maxoffset THEN GOTO, out |
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76 | a = assoc(num, bytarr(4, /nozero), offset) |
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77 | typefile = string(a[0]) |
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78 | ENDREP UNTIL typefile EQ 'GRIB' |
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79 | ENDIF |
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80 | ; |
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81 | start = [start, offset] |
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82 | ; |
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83 | a = assoc(num, bytarr(1, /nozero), offset+4) |
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84 | recsize = bit2int([binary(a[0]), binary(a[1]), binary(a[2])]) |
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85 | offset = offset+recsize |
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86 | previousrecsize = recsize |
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87 | ; |
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88 | ENDWHILE |
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89 | ; |
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90 | out: |
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91 | ; |
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92 | RETURN, start[1:n_elements(start)-1] |
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93 | END |
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