1 files changed, 94 insertions, 0 deletions
diff --git a/noao/onedspec/odcombine/src/icsection.x b/noao/onedspec/odcombine/src/icsection.x
new file mode 100644
index 00000000..746c1f51
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+++ b/noao/onedspec/odcombine/src/icsection.x
@@ -0,0 +1,94 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include	<ctype.h>
+
+# IC_SECTION -- Parse an image section into its elements.
+# 1. The default values must be set by the caller.
+# 2. A null image section is OK.
+# 3. The first nonwhitespace character must be '['.
+# 4. The last interpreted character must be ']'.
+#
+# This procedure should be replaced with an IMIO procedure at some
+# point.
+
+procedure ic_section (section, x1, x2, xs, ndim)
+
+char	section[ARB]		# Image section
+int	x1[ndim]		# Starting pixel
+int	x2[ndim]		# Ending pixel
+int	xs[ndim]		# Step
+int	ndim			# Number of dimensions
+
+int	i, ip, a, b, c, temp, ctoi()
+define	error_	99
+
+begin
+	# Decode the section string.
+	ip = 1
+	while (IS_WHITE(section[ip]))
+	    ip = ip + 1
+	if (section[ip] == '[')
+	    ip = ip + 1
+	else if (section[ip] == EOS)
+	    return
+	else
+	    goto error_
+
+	do i = 1, ndim {
+	    while (IS_WHITE(section[ip]))
+	        ip = ip + 1
+	    if (section[ip] == ']')
+		break
+
+	    # Default values
+	    a = x1[i]
+	    b = x2[i]
+	    c = xs[i]
+
+	    # Get a:b:c.  Allow notation such as "-*:c"
+	    # (or even "-:c") where the step is obviously negative.
+
+	    if (ctoi (section, ip, temp) > 0) {			# a
+		a = temp
+	        if (section[ip] == ':') {	
+		    ip = ip + 1
+		    if (ctoi (section, ip, b) == 0)		# a:b
+		        goto error_
+	        } else
+		    b = a
+	    } else if (section[ip] == '-') {			# -*
+		temp = a
+		a = b
+		b = temp
+	        ip = ip + 1
+	        if (section[ip] == '*')
+		    ip = ip + 1
+	    } else if (section[ip] == '*')			# *
+	        ip = ip + 1
+	    if (section[ip] == ':') {				# ..:step
+	        ip = ip + 1
+	        if (ctoi (section, ip, c) == 0)
+		    goto error_
+	        else if (c == 0)
+		    goto error_
+	    }
+	    if (a > b && c > 0)
+	        c = -c
+
+	    x1[i] = a
+	    x2[i] = b
+	    xs[i] = c
+
+	    while (IS_WHITE(section[ip]))
+	        ip = ip + 1
+	    if (section[ip] == ',')
+		ip = ip + 1
+	}
+
+	if (section[ip] != ']')
+	    goto error_
+
+	return
+error_
+	call error (0, "Error in image section specification")
+end