1 files changed, 58 insertions, 0 deletions
diff --git a/sys/plio/plrseg.h b/sys/plio/plrseg.h
new file mode 100644
index 00000000..f37372c3
--- /dev/null
+++ b/sys/plio/plrseg.h
@@ -0,0 +1,58 @@
+# PLRSEG.H -- Macros for sequentially reading segments of a range list.
+#
+#	       plr_init (rl, descriptor)
+#      npix = plr_nleft (descriptor)
+#      val = plr_getseg (rl, descriptor, npix, value)
+#
+# plr_init	Initialize descriptor for sequential i/o from the rangelist RL.
+# plr_nleft	Number of pixels left in the current line segment of constant
+#		  value.  Zero is returned at the EOL.
+# plr_getseg	Read NPIX pixels from the current segment, advancing to the
+#		  next segment automatically when the the current segment is
+#		  exhausted.
+#
+# The descriptor is an integer array, the contents of which are hidden from
+# the application using these macros.
+
+# Range list i/o descriptor.
+define	LEN_PLRDES	4
+define	rd_nleft	$1[1]
+define	rd_value	$1[2]
+define	rd_x		$1[3]
+define	rd_rn		$1[4]
+
+# PLR_INIT -- Initialize the rangelist descriptor.
+define	(plr_init, {			# $1=rl $2=des
+	rd_x($2) = 1
+	rd_rn($2) = RL_FIRST
+	plr_nextseg ($1, $2)
+})
+
+# PLR_NLEFT -- Number of pixels left in the current segment.
+define	plr_nleft	rd_nleft($1)
+
+# PLR_GETSEG -- Read pixels from the current segment.
+define	(plr_getseg, {			# $1=rl $2=des $3=npix $4=value
+	$4 = rd_value($2)
+	rd_x($2) = rd_x($2) + $3
+	rd_nleft($2) = rd_nleft($2) - $3
+	if (rd_nleft($2) <= 0)
+	    plr_nextseg ($1, $2)
+})
+	
+# PLR_NEXTSEG -- Set up the next segment (internal routine).
+define	(plr_nextseg, {			# $1=rl $2=des
+	if (rd_rn($2) <= RL_LEN($1)) {
+	    if ($1[1,rd_rn($2)] > rd_x($2)) {
+		rd_value($2) = 0
+		rd_nleft($2) = $1[1,rd_x($2)] - rd_x($2)
+	    } else {
+		rd_value($2) = $1[3,rd_rn($2)]
+		rd_nleft($2) = $1[2,rd_rn($2)]
+		rd_rn($2) = rd_rn($2) + 1
+	    }
+	} else if (rd_x($2) <= RL_AXLEN($1)) {
+	    rd_value($2) = 0
+	    rd_nleft($2) = RL_AXLEN($1) - rd_x($2) + 1
+	}
+})