1 files changed, 52 insertions, 0 deletions
diff --git a/pkg/system/help/getoption.x b/pkg/system/help/getoption.x
new file mode 100644
index 00000000..a7504531
--- /dev/null
+++ b/pkg/system/help/getoption.x
@@ -0,0 +1,52 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include	<ctype.h>
+include	"help.h"
+
+# GET_OPTION -- Map the possibly abbreviated option string into an integer
+# option code.  It is an error if the abbreviation is not unique.
+
+define	EQUAL		0
+
+int procedure get_option (opstr)
+
+char	opstr[ARB]		# option string, always lower case
+int	keycode[MAX_OPTIONS]
+int	oplen, key, ip, match
+int	strlen(), strncmp()
+
+string	keywords "help|sources|sysdoc|alldoc|files|summary|directory|references"
+data	keycode /O_HELP,O_SOURCE,O_SYSDOC,O_ALLDOC,O_FILES,O_SUMMARY,O_DIR,
+		 O_REFERENCES/
+
+begin
+	oplen = strlen (opstr)
+	ip = 1
+	match = 0
+
+	# Search the keyword table.  If the option string matches a keyword,
+	# it is either an exact match (oplen = keyword length) or a legal
+	# abbreviation.  If an abbreviation matches two keywords it is
+	# ambiguous and an error.
+
+	for (key=1;  keywords[ip] != EOS;  key=key+1) {
+	    if (strncmp (keywords[ip], opstr, oplen) == EQUAL) {
+		if (keywords[ip+oplen] == '|')
+		    return (keycode[key])		# exact match
+		else {
+		    if (match != 0)
+			call error (1, "ambiguous help option abbreviation")
+		    else
+			match = key
+		}
+	    }
+	    repeat {
+		ip = ip + 1
+	    } until (keywords[ip-1] == '|' || keywords[ip] == EOS)
+	}
+
+	if (match == 0)
+	    call error (2, "unknown help option")
+	else
+	    return (keycode[match])
+end