| 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 | ; @param RECSTART |
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| 12 | ; |
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| 13 | ; |
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| 14 | ; @returns |
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| 15 | ; |
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| 16 | ; |
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| 17 | ; @restrictions |
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| 18 | ; |
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| 19 | ; |
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| 20 | ; @examples |
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| 21 | ; |
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| 22 | ; |
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| 23 | ; @history |
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| 24 | ; |
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| 25 | ; |
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| 26 | ; @version |
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| 27 | ; $Id$ |
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| 28 | ;- |
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| 29 | ; |
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| 30 | FUNCTION read_grib_gds, num, recstart |
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| 31 | ; |
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| 32 | ; |
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| 33 | compile_opt idl2, strictarrsubs |
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| 34 | ; |
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| 35 | offset = recstart+8 |
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| 36 | a = assoc(num, bytarr(1, /nozero), offset-1) |
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| 37 | sizepds = bit2int([binary(a[1]), binary(a[2]), binary(a[3])]) |
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| 38 | ; |
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| 39 | offset = recstart+8+sizepds |
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| 40 | a = assoc(num, bytarr(1, /nozero), offset-1) |
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| 41 | ; |
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| 42 | sizegds = bit2int([binary(a[1]), binary(a[2]), binary(a[3])]) |
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| 43 | ; |
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| 44 | nv = (a[4])[0] |
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| 45 | pv = (a[5])[0] |
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| 46 | ; |
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| 47 | gridtype = (a[6])[0] |
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| 48 | ; |
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| 49 | CASE 1 OF |
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| 50 | ; Latitude/Longitude Grid |
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| 51 | ; Gaussian Latitude/Longitude Grid |
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| 52 | gridtype EQ 0 OR gridtype EQ 4:BEGIN |
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| 53 | ni = bit2int([binary(a[7]), binary(a[8])]) |
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| 54 | nj = bit2int([binary(a[9]), binary(a[10])]) |
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| 55 | ; |
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| 56 | la1 = bit2int([binary(a[11]), binary(a[12]), binary(a[13])], /checkneg)/1000. |
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| 57 | lo1 = bit2int([binary(a[14]), binary(a[15]), binary(a[16])], /checkneg)/1000. |
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| 58 | ; |
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| 59 | resflags = binary(a[17]) |
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| 60 | ; |
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| 61 | la2 = bit2int([binary(a[18]), binary(a[19]), binary(a[20])], /checkneg)/1000. |
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| 62 | lo2 = bit2int([binary(a[21]), binary(a[22]), binary(a[23])], /checkneg)/1000. |
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| 63 | ; |
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| 64 | di = bit2int([binary(a[24]), binary(a[25])])/1000. |
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| 65 | IF di EQ 65.5350 THEN di = -1 |
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| 66 | ; |
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| 67 | IF gridtype EQ 0 THEN BEGIN |
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| 68 | dj = bit2int([binary(a[26]), binary(a[27])])/1000. |
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| 69 | IF dj EQ 65.5350 THEN dj = -1 |
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| 70 | ENDIF ELSE BEGIN |
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| 71 | n = bit2int([binary(a[26]), binary(a[27])]) |
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| 72 | ENDELSE |
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| 73 | ; |
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| 74 | scanflags = binary(a[28]) |
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| 75 | ; |
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| 76 | res = {size:sizegds, gridtype:gridtype, ni:ni, nj:nj, la1:la1, la2:la2, lo1:lo1, lo2:lo2, di:di} |
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| 77 | IF gridtype EQ 0 THEN res = create_struct(res, 'dj', dj) $ |
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| 78 | ELSE res = create_struct(res, 'n', n) |
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| 79 | RETURN, res |
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| 80 | END |
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| 81 | ; Mercator Projection Grid |
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| 82 | gridtype EQ 1: |
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| 83 | ; Gnomonic Projection Grid |
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| 84 | gridtype EQ 2: |
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| 85 | ; Lambert Conformal, secant or tangent, conical or bipolar (normal or |
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| 86 | ; oblique) Projection Grid |
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| 87 | gridtype EQ 3: |
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| 88 | ; Polar Stereographic Projection Grid |
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| 89 | gridtype EQ 5: |
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| 90 | ; Oblique Lambert conformal, secant or tangent, conical or bipolar, |
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| 91 | ; projection |
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| 92 | gridtype EQ 13: |
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| 93 | ; Spherical Harmonic Coefficients |
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| 94 | gridtype EQ 50: |
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| 95 | ; Space view perspective or orthographic grid |
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| 96 | gridtype EQ 90: |
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| 97 | ; reserved - see Manual on Codes |
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| 98 | ELSE: |
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| 99 | ENDCASE |
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| 100 | ; |
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| 101 | RETURN, -1 |
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| 102 | END |
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