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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <syserr.h>
include <config.h>
include <imhdr.h>
include <imio.h>
include <mach.h>
# IMIOFF -- Initialize the physical dimensions of a new image. Compute and set
# the absolute file offsets of the major components of the pixel storage file.
procedure imioff (im, pixoff, compress, devblksz)
pointer im # image descriptor
long pixoff # file offset of first pixel
int compress # if set, do not align image lines
int devblksz # FIO device block size
real impkden, envgetr()
long offset, temp1, temp2, imnote()
int ndim, dim, sz_pixel, lblksize, pblksize
errchk imerr
include <szpixtype.inc>
begin
sz_pixel = pix_size[IM_PIXTYPE(im)]
pblksize = max (devblksz, SZ_VMPAGE)
if (compress == YES)
lblksize = 1
else
lblksize = devblksz
# Set the offset of the pixel storage area. Compute the physical
# dimensions of the axes of the image. If image compression is
# selected, the logical and physical lengths of the axes will be
# the same. Otherwise, the physical length of each line of the
# image will be increased to fill an integral number of device blocks.
IM_PIXOFF(im) = pixoff
call amovl (IM_LEN(im,1), IM_PHYSLEN(im,1), IM_MAXDIM)
call amovl (IM_LEN(im,1), IM_SVLEN(im,1), IM_MAXDIM)
ndim = IM_NDIM(im)
# If ndim was not explicitly set, compute it by counting the number
# of nonzero dimensions.
if (ndim == 0) {
for (ndim=1; IM_LEN(im,ndim) > 0 && ndim <= IM_MAXDIM;
ndim=ndim+1)
;
ndim = ndim - 1
IM_NDIM(im) = ndim
}
IM_NPHYSDIM(im) = ndim
# Make sure dimension stuff makes sense.
if (ndim < 0 || ndim > IM_MAXDIM)
call imerr (IM_NAME(im), SYS_IMNDIM)
do dim = 1, ndim
if (IM_LEN(im,dim) <= 0)
call imerr (IM_NAME(im), SYS_IMDIMLEN)
# Set the unused higher dimensions to 1. This makes is possible to
# access the image as if it were higher dimensional, and in a way it
# truely is.
do dim = ndim + 1, IM_MAXDIM
IM_LEN(im,dim) = 1
if (lblksize > 1) {
temp1 = pixoff + IM_LEN(im,1) * sz_pixel
temp2 = temp1
call imalign (temp2, lblksize)
# Only block lines if the packing density is above a certain
# threshold. Alignment is disabled if compress=YES since lblksize
# will have been set to 1.
iferr (impkden = envgetr ("impkden"))
impkden = IM_PACKDENSITY
if (real(temp1-pixoff) / real(temp2-pixoff) >= impkden)
IM_PHYSLEN(im,1) = (temp2 - pixoff) / sz_pixel
}
# Set the offsets of the histogram pixels and the bad pixel list.
# The HGMOFF offset marks the end of the pixel segment.
offset = imnote (im, IM_LEN(im,1))
call imalign (offset, pblksize)
IM_HGMOFF(im) = offset
offset = offset + (MAX_HGMLEN * SZ_REAL)
call imalign (offset, lblksize)
IM_BLIST(im) = offset
end
# IMALIGN -- Advance "offset" to the next block boundary.
procedure imalign (offset, blksize)
long offset
int blksize, diff
begin
diff = mod (offset-1, max (1, blksize))
if (diff != 0)
offset = offset + (blksize - diff)
end
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