subroutine compack(fld,ndpts,idrsnum,idrstmpl,cpack,lcpack) 1,19
!$$$ SUBPROGRAM DOCUMENTATION BLOCK
! . . . .
! SUBPROGRAM: compack
! PRGMMR: Gilbert ORG: W/NP11 DATE: 2000-06-21
!
! ABSTRACT: This subroutine packs up a data field using a complex
! packing algorithm as defined in the GRIB2 documention. It
! supports GRIB2 complex packing templates with or without
! spatial differences (i.e. DRTs 5.2 and 5.3).
! It also fills in GRIB2 Data Representation Template 5.2 or 5.3
! with the appropriate values.
!
! PROGRAM HISTORY LOG:
! 2000-06-21 Gilbert
!
! USAGE: CALL compack(fld,ndpts,idrsnum,idrstmpl,cpack,lcpack)
! INPUT ARGUMENT LIST:
! fld() - Contains the data values to pack
! ndpts - The number of data values in array fld()
! idrsnum - Data Representation Template number 5.N
! Must equal 2 or 3.
! idrstmpl - Contains the array of values for Data Representation
! Template 5.2 or 5.3
! (1) = Reference value - ignored on input
! (2) = Binary Scale Factor
! (3) = Decimal Scale Factor
! .
! .
! (7) = Missing value management
! (8) = Primary missing value
! (9) = Secondary missing value
! .
! .
! (17) = Order of Spatial Differencing ( 1 or 2 )
! .
! .
!
! OUTPUT ARGUMENT LIST:
! idrstmpl - Contains the array of values for Data Representation
! Template 5.3
! (1) = Reference value - set by compack routine.
! (2) = Binary Scale Factor - unchanged from input
! (3) = Decimal Scale Factor - unchanged from input
! .
! .
! cpack - The packed data field (character*1 array)
! lcpack - length of packed field cpack().
!
! REMARKS: None
!
! ATTRIBUTES:
! LANGUAGE: XL Fortran 90
! MACHINE: IBM SP
!
!$$$
integer,intent(in) :: ndpts,idrsnum
real,intent(in) :: fld(ndpts)
character(len=1),intent(out) :: cpack(*)
integer,intent(inout) :: idrstmpl(*)
integer,intent(out) :: lcpack
real(4) :: ref
integer(4) :: iref
integer,allocatable :: ifld(:)
integer,allocatable :: jmin(:),jmax(:),lbit(:)
integer,parameter :: zero=0
integer,allocatable :: gref(:),gwidth(:),glen(:)
integer :: glength,grpwidth
logical :: simple_alg = .false.
alog2=alog(2.0)
bscale=2.0**real(-idrstmpl(2))
dscale=10.0**real(idrstmpl(3))
!
! Find max and min values in the data
!
rmax=fld(1)
rmin=fld(1)
do j=2,ndpts
if (fld(j).gt.rmax) rmax=fld(j)
if (fld(j).lt.rmin) rmin=fld(j)
enddo
!
! If max and min values are not equal, pack up field.
! If they are equal, we have a constant field, and the reference
! value (rmin) is the value for each point in the field and
! set nbits to 0.
!
if (rmin.ne.rmax) then
iofst=0
allocate(ifld(ndpts))
allocate(gref(ndpts))
allocate(gwidth(ndpts))
allocate(glen(ndpts))
!
! Scale original data
!
if (idrstmpl(2).eq.0) then ! No binary scaling
imin=nint(rmin*dscale)
!imax=nint(rmax*dscale)
rmin=real(imin)
do j=1,ndpts
ifld(j)=nint(fld(j)*dscale)-imin
enddo
else ! Use binary scaling factor
rmin=rmin*dscale
!rmax=rmax*dscale
do j=1,ndpts
ifld(j)=nint(((fld(j)*dscale)-rmin)*bscale)
enddo
endif
!
! Calculate Spatial differences, if using DRS Template 5.3
!
if (idrsnum.eq.3) then ! spatial differences
if (idrstmpl(17).ne.1.and.idrstmpl(17).ne.2) idrstmpl(17)=2
if (idrstmpl(17).eq.1) then ! first order
ival1=ifld(1)
do j=ndpts,2,-1
ifld(j)=ifld(j)-ifld(j-1)
enddo
ifld(1)=0
elseif (idrstmpl(17).eq.2) then ! second order
ival1=ifld(1)
ival2=ifld(2)
do j=ndpts,3,-1
ifld(j)=ifld(j)-(2*ifld(j-1))+ifld(j-2)
enddo
ifld(1)=0
ifld(2)=0
endif
!
! subtract min value from spatial diff field
!
isd=idrstmpl(17)+1
minsd=minval(ifld(isd:ndpts))
do j=isd,ndpts
ifld(j)=ifld(j)-minsd
enddo
!
! find num of bits need to store minsd and add 1 extra bit
! to indicate sign
!
temp=alog(real(abs(minsd)+1))/alog2
nbitsd=ceiling(temp)+1
!
! find num of bits need to store ifld(1) ( and ifld(2)
! if using 2nd order differencing )
!
maxorig=ival1
if (idrstmpl(17).eq.2.and.ival2.gt.ival1) maxorig=ival2
temp=alog(real(maxorig+1))/alog2
nbitorig=ceiling(temp)+1
if (nbitorig.gt.nbitsd) nbitsd=nbitorig
! increase number of bits to even multiple of 8 ( octet )
if (mod(nbitsd,8).ne.0) nbitsd=nbitsd+(8-mod(nbitsd,8))
!
! Store extra spatial differencing info into the packed
! data section.
!
if (nbitsd.ne.0) then
! pack first original value
if (ival1.ge.0) then
call sbyte
(cpack,ival1,iofst,nbitsd)
iofst=iofst+nbitsd
else
call sbyte(cpack,1,iofst,1)
iofst=iofst+1
call sbyte(cpack,iabs(ival1),iofst,nbitsd-1)
iofst=iofst+nbitsd-1
endif
if (idrstmpl(17).eq.2) then
! pack second original value
if (ival2.ge.0) then
call sbyte(cpack,ival2,iofst,nbitsd)
iofst=iofst+nbitsd
else
call sbyte(cpack,1,iofst,1)
iofst=iofst+1
call sbyte(cpack,iabs(ival2),iofst,nbitsd-1)
iofst=iofst+nbitsd-1
endif
endif
! pack overall min of spatial differences
if (minsd.ge.0) then
call sbyte(cpack,minsd,iofst,nbitsd)
iofst=iofst+nbitsd
else
call sbyte(cpack,1,iofst,1)
iofst=iofst+1
call sbyte(cpack,iabs(minsd),iofst,nbitsd-1)
iofst=iofst+nbitsd-1
endif
endif
!print *,'SDp ',ival1,ival2,minsd,nbitsd
endif ! end of spatial diff section
!
! Determine Groups to be used.
!
if ( simple_alg ) then
! set group length to 10 : calculate number of groups
! and length of last group
ngroups=ndpts/10
glen(1:ngroups)=10
itemp=mod(ndpts,10)
if (itemp.ne.0) then
ngroups=ngroups+1
glen(ngroups)=itemp
endif
else
! Use Dr. Glahn's algorithm for determining grouping.
!
kfildo=6
minpk=10
inc=1
maxgrps=(ndpts/minpk)+1
allocate(jmin(maxgrps))
allocate(jmax(maxgrps))
allocate(lbit(maxgrps))
missopt=0
call pack_gp(kfildo,ifld,ndpts,missopt,minpk,inc,miss1,miss2,
& jmin,jmax,lbit,glen,maxgrps,ngroups,ibit,jbit,
& kbit,novref,lbitref,ier)
!print *,'SAGier = ',ier,ibit,jbit,kbit,novref,lbitref
do ng=1,ngroups
glen(ng)=glen(ng)+novref
enddo
deallocate(jmin)
deallocate(jmax)
deallocate(lbit)
endif
!
! For each group, find the group's reference value
! and the number of bits needed to hold the remaining values
!
n=1
do ng=1,ngroups
! find max and min values of group
gref(ng)=ifld(n)
imax=ifld(n)
j=n+1
do lg=2,glen(ng)
if (ifld(j).lt.gref(ng)) gref(ng)=ifld(j)
if (ifld(j).gt.imax) imax=ifld(j)
j=j+1
enddo
! calc num of bits needed to hold data
if ( gref(ng).ne.imax ) then
temp=alog(real(imax-gref(ng)+1))/alog2
gwidth(ng)=ceiling(temp)
else
gwidth(ng)=0
endif
! Subtract min from data
j=n
do lg=1,glen(ng)
ifld(j)=ifld(j)-gref(ng)
j=j+1
enddo
! increment fld array counter
n=n+glen(ng)
enddo
!
! Find max of the group references and calc num of bits needed
! to pack each groups reference value, then
! pack up group reference values
!
!write(77,*)'GREFS: ',(gref(j),j=1,ngroups)
igmax=maxval(gref(1:ngroups))
if (igmax.ne.0) then
temp=alog(real(igmax+1))/alog2
nbitsgref=ceiling(temp)
call sbytes(cpack,gref,iofst,nbitsgref,0,ngroups)
itemp=nbitsgref*ngroups
iofst=iofst+itemp
! Pad last octet with Zeros, if necessary,
if (mod(itemp,8).ne.0) then
left=8-mod(itemp,8)
call sbyte(cpack,zero,iofst,left)
iofst=iofst+left
endif
else
nbitsgref=0
endif
!
! Find max/min of the group widths and calc num of bits needed
! to pack each groups width value, then
! pack up group width values
!
!write(77,*)'GWIDTHS: ',(gwidth(j),j=1,ngroups)
iwmax=maxval(gwidth(1:ngroups))
ngwidthref=minval(gwidth(1:ngroups))
if (iwmax.ne.ngwidthref) then
temp=alog(real(iwmax-ngwidthref+1))/alog2
nbitsgwidth=ceiling(temp)
do i=1,ngroups
gwidth(i)=gwidth(i)-ngwidthref
enddo
call sbytes(cpack,gwidth,iofst,nbitsgwidth,0,ngroups)
itemp=nbitsgwidth*ngroups
iofst=iofst+itemp
! Pad last octet with Zeros, if necessary,
if (mod(itemp,8).ne.0) then
left=8-mod(itemp,8)
call sbyte(cpack,zero,iofst,left)
iofst=iofst+left
endif
else
nbitsgwidth=0
gwidth(1:ngroups)=0
endif
!
! Find max/min of the group lengths and calc num of bits needed
! to pack each groups length value, then
! pack up group length values
!
!write(77,*)'GLENS: ',(glen(j),j=1,ngroups)
ilmax=maxval(glen(1:ngroups-1))
nglenref=minval(glen(1:ngroups-1))
nglenlast=glen(ngroups)
if (ilmax.ne.nglenref) then
temp=alog(real(ilmax-nglenref+1))/alog2
nbitsglen=ceiling(temp)
do i=1,ngroups-1
glen(i)=glen(i)-nglenref
enddo
call sbytes(cpack,glen,iofst,nbitsglen,0,ngroups)
itemp=nbitsglen*ngroups
iofst=iofst+itemp
! Pad last octet with Zeros, if necessary,
if (mod(itemp,8).ne.0) then
left=8-mod(itemp,8)
call sbyte(cpack,zero,iofst,left)
iofst=iofst+left
endif
else
nbitsglen=0
glen(1:ngroups)=0
endif
!
! For each group, pack data values
!
!write(77,*)'IFLDS: ',(ifld(j),j=1,ndpts)
n=1
ij=0
do ng=1,ngroups
glength=glen(ng)+nglenref
if (ng.eq.ngroups ) glength=nglenlast
grpwidth=gwidth(ng)+ngwidthref
!write(77,*)'NGP ',ng,grpwidth,glength,gref(ng)
if ( grpwidth.ne.0 ) then
call sbytes(cpack,ifld(n),iofst,grpwidth,0,glength)
iofst=iofst+(grpwidth*glength)
endif
do kk=1,glength
ij=ij+1
!write(77,*)'SAG ',ij,fld(ij),ifld(ij),gref(ng),bscale,rmin,dscale
enddo
n=n+glength
enddo
! Pad last octet with Zeros, if necessary,
if (mod(iofst,8).ne.0) then
left=8-mod(iofst,8)
call sbyte(cpack,zero,iofst,left)
iofst=iofst+left
endif
lcpack=iofst/8
!
if ( allocated(ifld) ) deallocate(ifld)
if ( allocated(gref) ) deallocate(gref)
if ( allocated(gwidth) ) deallocate(gwidth)
if ( allocated(glen) ) deallocate(glen)
else ! Constant field ( max = min )
nbits=0
lcpack=0
nbitsgref=0
ngroups=0
endif
!
! Fill in ref value and number of bits in Template 5.2
!
call mkieee(rmin,ref,1) ! ensure reference value is IEEE format
! call gbyte(ref,idrstmpl(1),0,32)
iref=transfer(ref,iref)
idrstmpl(1)=iref
idrstmpl(4)=nbitsgref
idrstmpl(5)=0 ! original data were reals
idrstmpl(6)=1 ! general group splitting
idrstmpl(7)=0 ! No internal missing values
idrstmpl(8)=0 ! Primary missing value
idrstmpl(9)=0 ! secondary missing value
idrstmpl(10)=ngroups ! Number of groups
idrstmpl(11)=ngwidthref ! reference for group widths
idrstmpl(12)=nbitsgwidth ! num bits used for group widths
idrstmpl(13)=nglenref ! Reference for group lengths
idrstmpl(14)=1 ! length increment for group lengths
idrstmpl(15)=nglenlast ! True length of last group
idrstmpl(16)=nbitsglen ! num bits used for group lengths
if (idrsnum.eq.3) then
idrstmpl(18)=nbitsd/8 ! num bits used for extra spatial
! differencing values
endif
return
end