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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <mach.h>
include <config.h>
include <imhdr.h>
include "oif.h"
# IMF_INITOFFSETS -- 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 imf_initoffsets (im, dev_block_size)
pointer im
int dev_block_size
long offset, temp1, temp2
int ndim, dim, sz_pixel, lblksize, pblksize, sizeof()
begin
sz_pixel = sizeof (IM_PIXTYPE(im))
pblksize = max (dev_block_size, SZ_VMPAGE)
lblksize = dev_block_size
# Allow space for the pixhdr pixel storage file header. Advance
# "offset" to the next device block boundary.
offset = LEN_PIXHDR * SZ_MII_INT
call imf_align (offset, pblksize)
# 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) = offset
call amovl (IM_LEN(im,1), IM_PHYSLEN(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
}
# 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
temp1 = offset + IM_LEN(im,1) * sz_pixel
temp2 = temp1
call imf_align (temp2, lblksize)
# Only block lines if the packing density is above a certain threshold.
if (real(temp1-offset) / real(temp2-offset) >= IM_PACKDENSITY)
IM_PHYSLEN(im,1) = (temp2 - offset) / sz_pixel
# Set the offsets of the histogram pixels and the bad pixel list.
offset = IM_PHYSLEN(im,1)
do dim = 2, ndim
offset = offset * IM_LEN(im,dim)
offset = (offset * sz_pixel) + IM_PIXOFF(im)
call imf_align (offset, lblksize)
IM_HGMOFF(im) = offset
IM_BLIST(im) = offset
end
# IMF_ALIGN -- Advance "offset" to the next block boundary.
procedure imf_align (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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