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1 files changed, 48 insertions, 0 deletions

diff --git a/sys/gio/cursor/gtrfetch.x b/sys/gio/cursor/gtrfetch.x
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+++ b/sys/gio/cursor/gtrfetch.x
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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