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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <gio.h>
include <gki.h>
include "gtr.h"
# GTR_TRUNCATE -- Truncate the frame buffer, which has grown larger than
# the limit set by the user (or the system default). This is done by moving
# the metacode data at the end of the buffer (beginning with the word pointed
# to by gki) to the maximum upper limit of the buffer and adjusting the input
# and output pointers accordingly.
procedure gtr_truncate (tr, gki)
pointer tr # giotr descriptor
pointer gki # pointer to first word to be preserved
pointer top
int nwords
begin
# Find the first instruction preceding the soft upper limit on the
# size of the buffer.
top = TR_FRAMEBUF(tr) + TR_MAXLENFRAMEBUF(tr)
while (Mems[top] != BOI && top > TR_FRAMEBUF(tr))
top = top - 1
# Move the partial instruction likely to be at the end of the buffer
# to the new "top". Note that we can only truncate (discard)
# instructions which have already been executed, hence the partial
# instruction at the end of the buffer must be preserved.
if (gki != top) {
nwords = TR_OP(tr) - gki
call amovs (Mems[gki], Mems[top], nwords)
TR_IP(tr) = top
TR_OP(tr) = top + nwords
}
end
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