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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_FETCH_NEXT_INSTRUCTION -- Return a pointer to the next GKI metacode
# instruction in the input buffer. Only complete instructions resident in
# a contiguous section of memory are returned. EOF is returned when the
# end of the current buffer is reached, or when the last instruction in the
# frame buffer is not yet complete. EOF does not signify the end of the
# metacode stream.
int procedure gtr_fetch_next_instruction (tr, gki)
pointer tr # pointer to giotr descriptor
pointer gki # pointer to next instruction (output)
int nleft, length
pointer ip, itop
begin
ip = TR_IP(tr)
itop = TR_OP(tr)
# Search for the beginning of the next instruction.
while (Mems[ip] != BOI && ip < itop)
ip = ip + 1
nleft = itop - ip
if (nleft < 3) {
# The length field of the next instruction is not yet present.
TR_IP(tr) = ip
return (EOF)
} else {
length = Mems[ip+GKI_HDR_LENGTH-1]
if (length > nleft) {
# Entire instruction is not yet present in buffer.
TR_IP(tr) = ip
return (EOF)
} else {
# Entire instruction is present in buffer.
TR_IP(tr) = ip + length
gki = ip
return (length)
}
}
end
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