[67] | 1 | FUNCTION scan_grib_recstart, num |
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[114] | 2 | ; |
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| 3 | compile_opt idl2, strictarrsubs |
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| 4 | ; |
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[67] | 5 | |
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| 6 | infofile = fstat(num) |
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| 7 | ; minimum size of one record |
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| 8 | minisize = 8L+28L+4L+4L |
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| 9 | maxoffset = infofile.size-minisize |
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| 10 | ; |
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| 11 | start = 0L |
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| 12 | offset = 0L |
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| 13 | previousrecsize = 0L |
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| 14 | |
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| 15 | WHILE offset LT maxoffset DO BEGIN |
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| 16 | ; Every record must begin with 'GRIB'. |
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| 17 | ; However, their is no rule to define the space between 2 records. |
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| 18 | ; (1) we try space = previousrecsize MOD 8, because for echam outputs, |
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| 19 | ; the total size of the records is rounded to modulo 8 |
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| 20 | addoff = 8 - (previousrecsize MOD 8) |
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| 21 | offset = offset+addoff |
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| 22 | IF offset GE maxoffset THEN GOTO, out |
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| 23 | a = assoc(num, bytarr(4, /nozero), offset) |
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| 24 | typefile = string(a[0]) |
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| 25 | IF typefile NE 'GRIB' THEN offset = offset-addoff |
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| 26 | ; (2) we try space = previousrecsize MOD 120, because for ecmwf |
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| 27 | ; outputs, the total size of the records is rounded to modulo 120 |
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| 28 | addoff = 120 - (previousrecsize MOD 120) |
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| 29 | IF typefile NE 'GRIB' THEN BEGIN |
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| 30 | offset = offset+addoff |
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| 31 | IF offset GE maxoffset THEN GOTO, out |
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| 32 | a = assoc(num, bytarr(4, /nozero), offset) |
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| 33 | typefile = string(a[0]) |
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| 34 | IF typefile NE 'GRIB' THEN offset = offset-addoff |
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| 35 | ENDIF |
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| 36 | ; (3) we try space = 0 |
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| 37 | IF typefile NE 'GRIB' THEN BEGIN |
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| 38 | a = assoc(num, bytarr(4, /nozero), offset) |
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| 39 | typefile = string(a[0]) |
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| 40 | ENDIF |
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| 41 | ; (4) we try any value for space |
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| 42 | IF typefile NE 'GRIB' THEN BEGIN |
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| 43 | REPEAT BEGIN |
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| 44 | CASE 1 OF |
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| 45 | array_equal((a[0])[3 ], byte('G' )):offset = offset+3 |
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| 46 | array_equal((a[0])[2:3], byte('GR' )):offset = offset+2 |
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| 47 | array_equal((a[0])[1:3], byte('GRI')):offset = offset+1 |
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| 48 | else:offset = offset+4 |
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| 49 | ENDCASE |
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| 50 | IF offset GE maxoffset THEN GOTO, out |
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| 51 | a = assoc(num, bytarr(4, /nozero), offset) |
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| 52 | typefile = string(a[0]) |
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| 53 | ENDREP UNTIL typefile EQ 'GRIB' |
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| 54 | ENDIF |
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| 55 | ; |
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| 56 | start = [start, offset] |
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| 57 | ; |
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| 58 | a = assoc(num, bytarr(1, /nozero), offset+4) |
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| 59 | recsize = bit2int([binary(a[0]), binary(a[1]), binary(a[2])]) |
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| 60 | offset = offset+recsize |
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| 61 | previousrecsize = recsize |
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| 62 | ; |
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| 63 | ENDWHILE |
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| 64 | ; |
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| 65 | out: |
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| 66 | ; |
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| 67 | RETURN, start[1:n_elements(start)-1] |
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| 68 | END |
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