| 1 | subroutine compack(fld,ndpts,idrsnum,idrstmpl,cpack,lcpack) |
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| 2 | !$$$ SUBPROGRAM DOCUMENTATION BLOCK |
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| 3 | ! . . . . |
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| 4 | ! SUBPROGRAM: compack |
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| 5 | ! PRGMMR: Gilbert ORG: W/NP11 DATE: 2000-06-21 |
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| 6 | ! |
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| 7 | ! ABSTRACT: This subroutine packs up a data field using a complex |
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| 8 | ! packing algorithm as defined in the GRIB2 documention. It |
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| 9 | ! supports GRIB2 complex packing templates with or without |
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| 10 | ! spatial differences (i.e. DRTs 5.2 and 5.3). |
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| 11 | ! It also fills in GRIB2 Data Representation Template 5.2 or 5.3 |
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| 12 | ! with the appropriate values. |
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| 13 | ! |
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| 14 | ! PROGRAM HISTORY LOG: |
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| 15 | ! 2000-06-21 Gilbert |
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| 16 | ! |
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| 17 | ! USAGE: CALL compack(fld,ndpts,idrsnum,idrstmpl,cpack,lcpack) |
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| 18 | ! INPUT ARGUMENT LIST: |
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| 19 | ! fld() - Contains the data values to pack |
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| 20 | ! ndpts - The number of data values in array fld() |
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| 21 | ! idrsnum - Data Representation Template number 5.N |
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| 22 | ! Must equal 2 or 3. |
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| 23 | ! idrstmpl - Contains the array of values for Data Representation |
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| 24 | ! Template 5.2 or 5.3 |
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| 25 | ! (1) = Reference value - ignored on input |
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| 26 | ! (2) = Binary Scale Factor |
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| 27 | ! (3) = Decimal Scale Factor |
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| 28 | ! . |
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| 29 | ! . |
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| 30 | ! (7) = Missing value management |
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| 31 | ! (8) = Primary missing value |
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| 32 | ! (9) = Secondary missing value |
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| 33 | ! . |
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| 34 | ! . |
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| 35 | ! (17) = Order of Spatial Differencing ( 1 or 2 ) |
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| 36 | ! . |
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| 37 | ! . |
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| 38 | ! |
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| 39 | ! OUTPUT ARGUMENT LIST: |
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| 40 | ! idrstmpl - Contains the array of values for Data Representation |
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| 41 | ! Template 5.3 |
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| 42 | ! (1) = Reference value - set by compack routine. |
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| 43 | ! (2) = Binary Scale Factor - unchanged from input |
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| 44 | ! (3) = Decimal Scale Factor - unchanged from input |
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| 45 | ! . |
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| 46 | ! . |
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| 47 | ! cpack - The packed data field (character*1 array) |
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| 48 | ! lcpack - length of packed field cpack(). |
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| 49 | ! |
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| 50 | ! REMARKS: None |
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| 51 | ! |
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| 52 | ! ATTRIBUTES: |
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| 53 | ! LANGUAGE: XL Fortran 90 |
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| 54 | ! MACHINE: IBM SP |
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| 55 | ! |
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| 56 | !$$$ |
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| 57 | |
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| 58 | integer,intent(in) :: ndpts,idrsnum |
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| 59 | real,intent(in) :: fld(ndpts) |
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| 60 | character(len=1),intent(out) :: cpack(*) |
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| 61 | integer,intent(inout) :: idrstmpl(*) |
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| 62 | integer,intent(out) :: lcpack |
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| 63 | |
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| 64 | real(4) :: ref |
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| 65 | integer(4) :: iref |
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| 66 | integer,allocatable :: ifld(:) |
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| 67 | integer,allocatable :: jmin(:),jmax(:),lbit(:) |
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| 68 | integer,parameter :: zero=0 |
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| 69 | integer,allocatable :: gref(:),gwidth(:),glen(:) |
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| 70 | integer :: glength,grpwidth |
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| 71 | logical :: simple_alg = .false. |
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| 72 | |
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| 73 | alog2=alog(2.0) |
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| 74 | bscale=2.0**real(-idrstmpl(2)) |
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| 75 | dscale=10.0**real(idrstmpl(3)) |
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| 76 | ! |
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| 77 | ! Find max and min values in the data |
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| 78 | ! |
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| 79 | rmax=fld(1) |
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| 80 | rmin=fld(1) |
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| 81 | do j=2,ndpts |
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| 82 | if (fld(j).gt.rmax) rmax=fld(j) |
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| 83 | if (fld(j).lt.rmin) rmin=fld(j) |
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| 84 | enddo |
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| 85 | ! |
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| 86 | ! If max and min values are not equal, pack up field. |
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| 87 | ! If they are equal, we have a constant field, and the reference |
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| 88 | ! value (rmin) is the value for each point in the field and |
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| 89 | ! set nbits to 0. |
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| 90 | ! |
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| 91 | if (rmin.ne.rmax) then |
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| 92 | iofst=0 |
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| 93 | allocate(ifld(ndpts)) |
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| 94 | allocate(gref(ndpts)) |
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| 95 | allocate(gwidth(ndpts)) |
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| 96 | allocate(glen(ndpts)) |
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| 97 | ! |
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| 98 | ! Scale original data |
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| 99 | ! |
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| 100 | if (idrstmpl(2).eq.0) then ! No binary scaling |
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| 101 | imin=nint(rmin*dscale) |
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| 102 | !imax=nint(rmax*dscale) |
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| 103 | rmin=real(imin) |
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| 104 | do j=1,ndpts |
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| 105 | ifld(j)=nint(fld(j)*dscale)-imin |
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| 106 | enddo |
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| 107 | else ! Use binary scaling factor |
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| 108 | rmin=rmin*dscale |
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| 109 | !rmax=rmax*dscale |
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| 110 | do j=1,ndpts |
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| 111 | ifld(j)=nint(((fld(j)*dscale)-rmin)*bscale) |
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| 112 | enddo |
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| 113 | endif |
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| 114 | ! |
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| 115 | ! Calculate Spatial differences, if using DRS Template 5.3 |
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| 116 | ! |
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| 117 | if (idrsnum.eq.3) then ! spatial differences |
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| 118 | if (idrstmpl(17).ne.1.and.idrstmpl(17).ne.2) idrstmpl(17)=2 |
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| 119 | if (idrstmpl(17).eq.1) then ! first order |
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| 120 | ival1=ifld(1) |
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| 121 | do j=ndpts,2,-1 |
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| 122 | ifld(j)=ifld(j)-ifld(j-1) |
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| 123 | enddo |
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| 124 | ifld(1)=0 |
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| 125 | elseif (idrstmpl(17).eq.2) then ! second order |
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| 126 | ival1=ifld(1) |
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| 127 | ival2=ifld(2) |
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| 128 | do j=ndpts,3,-1 |
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| 129 | ifld(j)=ifld(j)-(2*ifld(j-1))+ifld(j-2) |
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| 130 | enddo |
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| 131 | ifld(1)=0 |
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| 132 | ifld(2)=0 |
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| 133 | endif |
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| 134 | ! |
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| 135 | ! subtract min value from spatial diff field |
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| 136 | ! |
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| 137 | isd=idrstmpl(17)+1 |
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| 138 | minsd=minval(ifld(isd:ndpts)) |
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| 139 | do j=isd,ndpts |
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| 140 | ifld(j)=ifld(j)-minsd |
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| 141 | enddo |
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| 142 | ! |
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| 143 | ! find num of bits need to store minsd and add 1 extra bit |
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| 144 | ! to indicate sign |
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| 145 | ! |
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| 146 | temp=alog(real(abs(minsd)+1))/alog2 |
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| 147 | nbitsd=ceiling(temp)+1 |
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| 148 | ! |
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| 149 | ! find num of bits need to store ifld(1) ( and ifld(2) |
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| 150 | ! if using 2nd order differencing ) |
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| 151 | ! |
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| 152 | maxorig=ival1 |
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| 153 | if (idrstmpl(17).eq.2.and.ival2.gt.ival1) maxorig=ival2 |
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| 154 | temp=alog(real(maxorig+1))/alog2 |
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| 155 | nbitorig=ceiling(temp)+1 |
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| 156 | if (nbitorig.gt.nbitsd) nbitsd=nbitorig |
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| 157 | ! increase number of bits to even multiple of 8 ( octet ) |
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| 158 | if (mod(nbitsd,8).ne.0) nbitsd=nbitsd+(8-mod(nbitsd,8)) |
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| 159 | ! |
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| 160 | ! Store extra spatial differencing info into the packed |
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| 161 | ! data section. |
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| 162 | ! |
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| 163 | if (nbitsd.ne.0) then |
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| 164 | ! pack first original value |
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| 165 | if (ival1.ge.0) then |
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| 166 | call g2lib_sbyte(cpack,ival1,iofst,nbitsd) |
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| 167 | iofst=iofst+nbitsd |
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| 168 | else |
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| 169 | call g2lib_sbyte(cpack,1,iofst,1) |
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| 170 | iofst=iofst+1 |
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| 171 | call g2lib_sbyte(cpack,iabs(ival1),iofst,nbitsd-1) |
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| 172 | iofst=iofst+nbitsd-1 |
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| 173 | endif |
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| 174 | if (idrstmpl(17).eq.2) then |
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| 175 | ! pack second original value |
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| 176 | if (ival2.ge.0) then |
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| 177 | call g2lib_sbyte(cpack,ival2,iofst,nbitsd) |
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| 178 | iofst=iofst+nbitsd |
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| 179 | else |
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| 180 | call g2lib_sbyte(cpack,1,iofst,1) |
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| 181 | iofst=iofst+1 |
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| 182 | call g2lib_sbyte(cpack,iabs(ival2),iofst,nbitsd-1) |
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| 183 | iofst=iofst+nbitsd-1 |
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| 184 | endif |
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| 185 | endif |
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| 186 | ! pack overall min of spatial differences |
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| 187 | if (minsd.ge.0) then |
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| 188 | call g2lib_sbyte(cpack,minsd,iofst,nbitsd) |
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| 189 | iofst=iofst+nbitsd |
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| 190 | else |
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| 191 | call g2lib_sbyte(cpack,1,iofst,1) |
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| 192 | iofst=iofst+1 |
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| 193 | call g2lib_sbyte(cpack,iabs(minsd),iofst,nbitsd-1) |
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| 194 | iofst=iofst+nbitsd-1 |
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| 195 | endif |
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| 196 | endif |
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| 197 | !print *,'SDp ',ival1,ival2,minsd,nbitsd |
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| 198 | endif ! end of spatial diff section |
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| 199 | ! |
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| 200 | ! Determine Groups to be used. |
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| 201 | ! |
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| 202 | if ( simple_alg ) then |
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| 203 | ! set group length to 10 : calculate number of groups |
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| 204 | ! and length of last group |
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| 205 | ngroups=ndpts/10 |
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| 206 | glen(1:ngroups)=10 |
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| 207 | itemp=mod(ndpts,10) |
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| 208 | if (itemp.ne.0) then |
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| 209 | ngroups=ngroups+1 |
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| 210 | glen(ngroups)=itemp |
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| 211 | endif |
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| 212 | else |
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| 213 | ! Use Dr. Glahn's algorithm for determining grouping. |
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| 214 | ! |
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| 215 | kfildo=6 |
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| 216 | minpk=10 |
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| 217 | inc=1 |
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| 218 | maxgrps=(ndpts/minpk)+1 |
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| 219 | allocate(jmin(maxgrps)) |
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| 220 | allocate(jmax(maxgrps)) |
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| 221 | allocate(lbit(maxgrps)) |
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| 222 | missopt=0 |
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| 223 | call pack_gp(kfildo,ifld,ndpts,missopt,minpk,inc,miss1,miss2, |
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| 224 | & jmin,jmax,lbit,glen,maxgrps,ngroups,ibit,jbit, |
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| 225 | & kbit,novref,lbitref,ier) |
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| 226 | !print *,'SAGier = ',ier,ibit,jbit,kbit,novref,lbitref |
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| 227 | do ng=1,ngroups |
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| 228 | glen(ng)=glen(ng)+novref |
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| 229 | enddo |
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| 230 | deallocate(jmin) |
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| 231 | deallocate(jmax) |
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| 232 | deallocate(lbit) |
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| 233 | endif |
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| 234 | ! |
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| 235 | ! For each group, find the group's reference value |
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| 236 | ! and the number of bits needed to hold the remaining values |
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| 237 | ! |
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| 238 | n=1 |
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| 239 | do ng=1,ngroups |
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| 240 | ! find max and min values of group |
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| 241 | gref(ng)=ifld(n) |
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| 242 | imax=ifld(n) |
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| 243 | j=n+1 |
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| 244 | do lg=2,glen(ng) |
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| 245 | if (ifld(j).lt.gref(ng)) gref(ng)=ifld(j) |
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| 246 | if (ifld(j).gt.imax) imax=ifld(j) |
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| 247 | j=j+1 |
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| 248 | enddo |
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| 249 | ! calc num of bits needed to hold data |
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| 250 | if ( gref(ng).ne.imax ) then |
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| 251 | temp=alog(real(imax-gref(ng)+1))/alog2 |
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| 252 | gwidth(ng)=ceiling(temp) |
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| 253 | else |
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| 254 | gwidth(ng)=0 |
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| 255 | endif |
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| 256 | ! Subtract min from data |
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| 257 | j=n |
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| 258 | do lg=1,glen(ng) |
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| 259 | ifld(j)=ifld(j)-gref(ng) |
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| 260 | j=j+1 |
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| 261 | enddo |
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| 262 | ! increment fld array counter |
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| 263 | n=n+glen(ng) |
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| 264 | enddo |
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| 265 | ! |
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| 266 | ! Find max of the group references and calc num of bits needed |
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| 267 | ! to pack each groups reference value, then |
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| 268 | ! pack up group reference values |
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| 269 | ! |
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| 270 | !write(77,*)'GREFS: ',(gref(j),j=1,ngroups) |
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| 271 | igmax=maxval(gref(1:ngroups)) |
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| 272 | if (igmax.ne.0) then |
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| 273 | temp=alog(real(igmax+1))/alog2 |
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| 274 | nbitsgref=ceiling(temp) |
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| 275 | call g2lib_sbytes(cpack,gref,iofst,nbitsgref,0,ngroups) |
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| 276 | itemp=nbitsgref*ngroups |
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| 277 | iofst=iofst+itemp |
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| 278 | ! Pad last octet with Zeros, if necessary, |
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| 279 | if (mod(itemp,8).ne.0) then |
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| 280 | left=8-mod(itemp,8) |
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| 281 | call g2lib_sbyte(cpack,zero,iofst,left) |
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| 282 | iofst=iofst+left |
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| 283 | endif |
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| 284 | else |
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| 285 | nbitsgref=0 |
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| 286 | endif |
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| 287 | ! |
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| 288 | ! Find max/min of the group widths and calc num of bits needed |
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| 289 | ! to pack each groups width value, then |
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| 290 | ! pack up group width values |
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| 291 | ! |
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| 292 | !write(77,*)'GWIDTHS: ',(gwidth(j),j=1,ngroups) |
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| 293 | iwmax=maxval(gwidth(1:ngroups)) |
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| 294 | ngwidthref=minval(gwidth(1:ngroups)) |
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| 295 | if (iwmax.ne.ngwidthref) then |
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| 296 | temp=alog(real(iwmax-ngwidthref+1))/alog2 |
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| 297 | nbitsgwidth=ceiling(temp) |
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| 298 | do i=1,ngroups |
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| 299 | gwidth(i)=gwidth(i)-ngwidthref |
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| 300 | enddo |
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| 301 | call g2lib_sbytes(cpack,gwidth,iofst,nbitsgwidth,0,ngroups) |
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| 302 | itemp=nbitsgwidth*ngroups |
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| 303 | iofst=iofst+itemp |
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| 304 | ! Pad last octet with Zeros, if necessary, |
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| 305 | if (mod(itemp,8).ne.0) then |
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| 306 | left=8-mod(itemp,8) |
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| 307 | call g2lib_sbyte(cpack,zero,iofst,left) |
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| 308 | iofst=iofst+left |
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| 309 | endif |
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| 310 | else |
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| 311 | nbitsgwidth=0 |
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| 312 | gwidth(1:ngroups)=0 |
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| 313 | endif |
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| 314 | ! |
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| 315 | ! Find max/min of the group lengths and calc num of bits needed |
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| 316 | ! to pack each groups length value, then |
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| 317 | ! pack up group length values |
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| 318 | ! |
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| 319 | !write(77,*)'GLENS: ',(glen(j),j=1,ngroups) |
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| 320 | ilmax=maxval(glen(1:ngroups-1)) |
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| 321 | nglenref=minval(glen(1:ngroups-1)) |
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| 322 | nglenlast=glen(ngroups) |
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| 323 | if (ilmax.ne.nglenref) then |
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| 324 | temp=alog(real(ilmax-nglenref+1))/alog2 |
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| 325 | nbitsglen=ceiling(temp) |
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| 326 | do i=1,ngroups-1 |
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| 327 | glen(i)=glen(i)-nglenref |
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| 328 | enddo |
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| 329 | call g2lib_sbytes(cpack,glen,iofst,nbitsglen,0,ngroups) |
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| 330 | itemp=nbitsglen*ngroups |
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| 331 | iofst=iofst+itemp |
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| 332 | ! Pad last octet with Zeros, if necessary, |
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| 333 | if (mod(itemp,8).ne.0) then |
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| 334 | left=8-mod(itemp,8) |
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| 335 | call g2lib_sbyte(cpack,zero,iofst,left) |
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| 336 | iofst=iofst+left |
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| 337 | endif |
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| 338 | else |
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| 339 | nbitsglen=0 |
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| 340 | glen(1:ngroups)=0 |
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| 341 | endif |
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| 342 | ! |
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| 343 | ! For each group, pack data values |
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| 344 | ! |
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| 345 | !write(77,*)'IFLDS: ',(ifld(j),j=1,ndpts) |
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| 346 | n=1 |
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| 347 | ij=0 |
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| 348 | do ng=1,ngroups |
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| 349 | glength=glen(ng)+nglenref |
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| 350 | if (ng.eq.ngroups ) glength=nglenlast |
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| 351 | grpwidth=gwidth(ng)+ngwidthref |
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| 352 | !write(77,*)'NGP ',ng,grpwidth,glength,gref(ng) |
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| 353 | if ( grpwidth.ne.0 ) then |
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| 354 | call g2lib_sbytes(cpack,ifld(n),iofst,grpwidth,0,glength) |
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| 355 | iofst=iofst+(grpwidth*glength) |
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| 356 | endif |
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| 357 | do kk=1,glength |
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| 358 | ij=ij+1 |
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| 359 | !write(77,*)'SAG ',ij,fld(ij),ifld(ij),gref(ng),bscale,rmin,dscale |
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| 360 | enddo |
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| 361 | n=n+glength |
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| 362 | enddo |
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| 363 | ! Pad last octet with Zeros, if necessary, |
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| 364 | if (mod(iofst,8).ne.0) then |
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| 365 | left=8-mod(iofst,8) |
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| 366 | call g2lib_sbyte(cpack,zero,iofst,left) |
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| 367 | iofst=iofst+left |
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| 368 | endif |
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| 369 | lcpack=iofst/8 |
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| 370 | ! |
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| 371 | if ( allocated(ifld) ) deallocate(ifld) |
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| 372 | if ( allocated(gref) ) deallocate(gref) |
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| 373 | if ( allocated(gwidth) ) deallocate(gwidth) |
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| 374 | if ( allocated(glen) ) deallocate(glen) |
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| 375 | else ! Constant field ( max = min ) |
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| 376 | nbits=0 |
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| 377 | lcpack=0 |
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| 378 | nbitsgref=0 |
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| 379 | ngroups=0 |
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| 380 | endif |
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| 381 | |
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| 382 | ! |
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| 383 | ! Fill in ref value and number of bits in Template 5.2 |
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| 384 | ! |
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| 385 | call mkieee(rmin,ref,1) ! ensure reference value is IEEE format |
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| 386 | ! call g2lib_gbyte(ref,idrstmpl(1),0,32) |
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| 387 | iref=transfer(ref,iref) |
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| 388 | idrstmpl(1)=iref |
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| 389 | idrstmpl(4)=nbitsgref |
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| 390 | idrstmpl(5)=0 ! original data were reals |
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| 391 | idrstmpl(6)=1 ! general group splitting |
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| 392 | idrstmpl(7)=0 ! No internal missing values |
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| 393 | idrstmpl(8)=0 ! Primary missing value |
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| 394 | idrstmpl(9)=0 ! secondary missing value |
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| 395 | idrstmpl(10)=ngroups ! Number of groups |
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| 396 | idrstmpl(11)=ngwidthref ! reference for group widths |
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| 397 | idrstmpl(12)=nbitsgwidth ! num bits used for group widths |
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| 398 | idrstmpl(13)=nglenref ! Reference for group lengths |
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| 399 | idrstmpl(14)=1 ! length increment for group lengths |
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| 400 | idrstmpl(15)=nglenlast ! True length of last group |
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| 401 | idrstmpl(16)=nbitsglen ! num bits used for group lengths |
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| 402 | if (idrsnum.eq.3) then |
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| 403 | idrstmpl(18)=nbitsd/8 ! num bits used for extra spatial |
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| 404 | ! differencing values |
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| 405 | endif |
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| 406 | |
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| 407 | return |
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| 408 | end |
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