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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <syserr.h>
include <gescape.h>
include <fset.h>
include <gio.h>
# GIM_READCOLORMAP -- Read a segment of a colormap. The number of cells
# read is returned. The number of cells read may be less than the request
# size if the cells have not yet been allocated.
int procedure gim_readcolormap (gp, colormap, first, maxelem, r, g, b)
pointer gp #I graphics descriptor
int colormap #I colormap number (0=screen)
int first #I first colormap entry to be read
int maxelem #I number of elements to read
int r[ARB],g[ARB],b[ARB] #O RGB color values (0-255)
pointer sp, cm, ip
int ncells, nret, nchars, i
short gim[GIM_READCMAP_LEN]
short retval[GIM_RET_RCMAP_LEN]
int read()
string s_readcmap "gim_readcolormap"
errchk flush, read, syserrs
begin
call smark (sp)
call gpl_flush()
gim[GIM_READCMAP_MP] = colormap
gim[GIM_READCMAP_FC] = first
gim[GIM_READCMAP_NC] = maxelem
call gescape (gp, GIM_READCMAP, gim, GIM_READCMAP_LEN)
call flush (GP_FD(gp))
# Get return value instruction header.
nchars = GIM_RET_RCMAP_LEN * SZ_SHORT
if (read (GP_FD(gp), retval, nchars) != nchars) {
call fseti (GP_FD(gp), F_CANCEL, OK)
call syserrs (SYS_FREAD, s_readcmap)
}
ncells = retval[GIM_RET_RCMAP_NC]
call salloc (cm, ncells * 3, TY_SHORT)
nret = min (ncells, maxelem)
# Get the colormap data.
nchars = (ncells * 3) * SZ_SHORT
if (read (GP_FD(gp), Mems[cm], nchars) != nchars) {
call fseti (GP_FD(gp), F_CANCEL, OK)
call syserrs (SYS_FREAD, s_readcmap)
}
do i = 1, nret {
ip = cm + (i - 1) * 3
r[i] = Mems[ip+0]
g[i] = Mems[ip+1]
b[i] = Mems[ip+2]
}
call fseti (GP_FD(gp), F_CANCEL, OK)
call sfree (sp)
return (nret)
end
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