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Diffstat (limited to 'pkg/tbtables/fitsio/ftgcxi.f')
| -rw-r--r-- | pkg/tbtables/fitsio/ftgcxi.f | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/pkg/tbtables/fitsio/ftgcxi.f b/pkg/tbtables/fitsio/ftgcxi.f new file mode 100644 index 00000000..d545a372 --- /dev/null +++ b/pkg/tbtables/fitsio/ftgcxi.f @@ -0,0 +1,86 @@ +C---------------------------------------------------------------------- + subroutine ftgcxi(iunit,colnum,frow,nrow,fbit,nbit, + & ivalue,status) + +C read any consecutive bits from an 'X' or 'B' column as an unsigned +C n-bit integer, unless nbits=16 in which case the 16 bits +C are interpreted as a 16-bit signed 2s complement word + +C iunit i fortran unit number +C colnum i number of the column to read +C frow i first row to read +C nrow i number of rows to read +C fbit i first bit within the row to read +C nbit i number of bits to read +C ivalue i*2 returned integer value(s) +C status i output error status +C +C written by Wm Pence, HEASARC/GSFC, Nov 1994 + +C COMMON BLOCK DEFINITIONS:-------------------------------------------- + integer nf,nb,ne + parameter (nb = 20) + parameter (nf = 3000) + 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----------------------------------- + + integer iunit,colnum,fbit,nbit,frow,nrow,status,i,j,k,row,ibuff + integer*2 ivalue(*),ival,power2(16) + logical lray(16) + save power2 + data power2/1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192, + & 16384,0/ + + if (status .gt. 0)return + + ibuff=bufnum(iunit) + + if (nbit .gt. 16)then + call ftpmsg('Cannot read more than 16 bits (ftgcxi)') + status=308 + return + else if ((fbit+nbit+6)/8 .gt. trept(colnum+tstart(ibuff)))then + call ftpmsg('Asked to read more bits than exist in'// + & ' the column (ftgcxi)') + status=308 + return + end if + + + row=frow-1 + do 30 k=1,nrow + row=row+1 +C get the individual bits + call ftgcx(iunit,colnum,row,fbit,nbit,lray,status) + if (status .gt. 0)return + ival=0 + j=0 + if (nbit .eq. 16 .and. lray(1))then +C interprete this as a 16 bit negative integer + do 10 i=16,2,-1 + j=j+1 + if (.not. lray(i))ival=ival+power2(j) +10 continue +C make 2's complement + ivalue(k)=-ival-1 + else +C reconstruct the positive integer value + do 20 i=nbit,1,-1 + j=j+1 + if (lray(i))ival=ival+power2(j) +20 continue + ivalue(k)=ival + end if +30 continue + end |