diff options
Diffstat (limited to 'pkg/tbtables/fitsio/ftpcks.f')
| -rw-r--r-- | pkg/tbtables/fitsio/ftpcks.f | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/pkg/tbtables/fitsio/ftpcks.f b/pkg/tbtables/fitsio/ftpcks.f new file mode 100644 index 00000000..f09bbdd6 --- /dev/null +++ b/pkg/tbtables/fitsio/ftpcks.f @@ -0,0 +1,170 @@ +C---------------------------------------------------------------------- + subroutine ftpcks(iunit,status) + +C Create or update the checksum keywords in the CHU. These keywords +C provide a checksum verification of the FITS HDU based on the ASCII +C coded 1's complement checksum algorithm developed by Rob Seaman at NOAO. + +C iunit i fortran unit number +C status i output error status +C +C written by Wm Pence, HEASARC/GSFC, Sept, 1994 + + integer iunit,status + +C-------COMMON BLOCK DEFINITIONS:-------------------------------------------- + integer nf,nb,ne + parameter (nf = 3000) + parameter (nb = 20) + parameter (ne = 200) + integer bufnum,chdu,hdutyp,maxhdu,hdstrt,hdend,nxthdr,dtstrt + integer nxtfld + logical wrmode + common/ft0001/bufnum(199),chdu(nb),hdutyp(nb),maxhdu(nb), + & wrmode(nb),hdstrt(nb,ne),hdend(nb),nxthdr(nb),dtstrt(nb),nxtfld + integer tfield,tstart,tbcol,rowlen,tdtype,trept,tnull,scount + integer theap,nxheap + double precision tscale,tzero + common/ft0002/tfield(nb),tstart(nb),tbcol(nf),rowlen(nb), + & tdtype(nf),trept(nf),tscale(nf),tzero(nf),tnull(nf),scount(nb) + & ,theap(nb),nxheap(nb) +C-------END OF COMMON BLOCK DEFINITIONS----------------------------------- + + double precision sum,dsum,odsum + integer ibuff,nrec,dd,mm,yy,dummy,i,tstat + character datstr*8,string*16,comm*40,oldcks*16,datsum*20 + logical complm + + if (status .gt. 0)return + + ibuff=bufnum(iunit) + +C generate current date string to put into the keyword comment + call ftgsdt(dd,mm,yy,status) + if (status .gt. 0)return + + datstr=' / / ' + write(datstr(1:2),1001)dd + write(datstr(4:5),1001)mm + write(datstr(7:8),1001)yy +1001 format(i2) + +C replace blank with leading 0 in each field if required + if (datstr(1:1) .eq. ' ')datstr(1:1)='0' + if (datstr(4:4) .eq. ' ')datstr(4:4)='0' + if (datstr(7:7) .eq. ' ')datstr(7:7)='0' + +C get the checksum keyword, if it exists, otherwise initialize it + tstat=status + call ftgkys(iunit,'CHECKSUM',oldcks,comm,status) + if (status .eq. 202)then + status=tstat + oldcks=' ' + comm='encoded HDU checksum updated on '//datstr + call ftpkys(iunit,'CHECKSUM','0000000000000000',comm,status) + end if + +C get the DATASUM keyword and convert it to a double precision value +C if it exists, otherwise initialize it + tstat=status + call ftgkys(iunit,'DATASUM',datsum,comm,status) + if (status .eq. 202)then + status=tstat + odsum=0. +C set the CHECKSUM keyword as undefined + oldcks=' ' + comm='data unit checksum updated on '//datstr + call ftpkys(iunit,'DATASUM',' 0',comm,status) + else +C decode the datasum into a double precision variable + do 10 i=1,20 + if (datsum(i:i) .ne. ' ')then + call ftc2dd(datsum(i:20),odsum,status) + if (status .eq. 409)then +C couldn't read the keyword; assume it is out of date + status=tstat + odsum=-1. + end if + go to 15 + end if +10 continue + odsum=0. + end if + +C rewrite the header END card, and following blank fill +15 call ftwend(iunit,status) + if (status .gt. 0)return + +C now re-read the required keywords to determine the structure + call ftrhdu(iunit,dummy,status) + +C write the correct data fill values, if they are not already correct + call ftpdfl(iunit,status) + +C calc. checksum of the data records; first, calc number of data records + nrec=(hdstrt(ibuff,chdu(ibuff)+1)-dtstrt(ibuff))/2880 + dsum=0. + + if (nrec .gt. 0)then +C move to the start of the data + call ftmbyt(iunit,dtstrt(ibuff),.true.,status) + +C accumulate the 32-bit 1's complement checksum + call ftcsum(iunit,nrec,dsum,status) + end if + + if (dsum .ne. odsum)then +C modify the DATASUM keyword with the correct value + comm='data unit checksum updated on '//datstr +C write the datasum into an I10 integer string + write(datsum,2000)dsum +2000 format(f11.0) + call ftmkys(iunit,'DATASUM',datsum(1:10),comm,status) +C set the CHECKSUM keyword as undefined + oldcks=' ' + end if + +C if DATASUM was correct, check if CHECKSUM is still OK + if (oldcks .ne. ' ')then + +C move to the start of the header + call ftmbyt(iunit,hdstrt(ibuff,chdu(ibuff)),.true.,status) + +C accumulate the header checksum into the previous data checksum + nrec= (dtstrt(ibuff)-hdstrt(ibuff,chdu(ibuff)))/2880 + sum=dsum + call ftcsum(iunit,nrec,sum,status) + +C encode the COMPLEMENT of the checksum into a 16-character string + complm=.true. + call ftesum(sum,complm,string) + +C return if the checksum is correct + if (string .eq. '0000000000000000')then + return + else if (oldcks .eq. '0000000000000000')then +C update the CHECKSUM keyword value with the checksum string + call ftmkys(iunit,'CHECKSUM',string,'&',status) + return + end if + end if + +C Zero the checksum and compute the new value + comm='encoded HDU checksum updated on '//datstr + call ftmkys(iunit,'CHECKSUM','0000000000000000',comm,status) + +C move to the start of the header + call ftmbyt(iunit,hdstrt(ibuff,chdu(ibuff)),.true.,status) + +C accumulate the header checksum into the previous data checksum + nrec= (dtstrt(ibuff)-hdstrt(ibuff,chdu(ibuff)))/2880 + sum=dsum + call ftcsum(iunit,nrec,sum,status) + +C encode the COMPLEMENT of the checksum into a 16-character string + complm=.true. + call ftesum(sum,complm,string) + +C update the CHECKSUM keyword value with the checksum string + call ftmkys(iunit,'CHECKSUM',string,'&',status) + end |