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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <gio.h>
# GCANCEL -- Cancel any buffered graphics output (as far as possible). Should
# be called by interrupt handlers to avoid leaving GIO in a funny state
# following an interrupt.
#
# As far as possible, GKI instructions are built up in internal storage and
# written to the output file in a single write. This decreases the likliehood
# of leaving a botched instruction in the output stream in response to an
# interrupt. Do not call FSETI to cancel the file output because that will
# almost certainly guarantee a botched instruction. Instead, we discard any
# partially built polylines still in GPL storage and append the GKI_CANCEL to
# the output instruction stream. The cancel instruction is passed on to the
# graphics kernel which eventually calls FSETI to cancel its output file
# buffer (containing device instructions). If a metacode reader does detect
# a botched instruction it will scan forward for the next BOI to try to resync
# the instruction stream.
procedure gcancel (gp)
pointer gp # graphics descriptor
int and()
begin
if (and (GP_GFLAGS(gp), GF_WSOPEN) != 0) {
call gki_cancel (GP_FD(gp))
call gki_fflush (GP_FD(gp))
}
call gfrinit (gp)
end
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