1 files changed, 55 insertions, 0 deletions
diff --git a/sys/fmtio/strsearch.x b/sys/fmtio/strsearch.x
new file mode 100644
index 00000000..e3006ed8
--- /dev/null
+++ b/sys/fmtio/strsearch.x
@@ -0,0 +1,55 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+# STRSEARCH -- Search a string for a substring.  This is the simplest and
+# fastest member of the pattern matching family.  A significant increase in
+# efficiency will result if this procedure is used to search for substrings
+# that do not use any metacharacters.
+
+int procedure strsearch (str, patstr)
+
+char	str[ARB]		# string to be searched
+char	patstr[ARB]		# substring to search for
+
+int	first_char, ch
+int	ip, patlen
+bool	strse1()
+
+begin
+	# The null pattern matches any string.
+	if (patstr[1] == EOS)
+	    return (1)
+
+	first_char = patstr[1]
+
+	do ip = 1, ARB {
+	    ch = str[ip]
+	    if (ch == EOS)
+		break
+	    if (ch == first_char)
+		if (strse1 (str[ip], patstr, patlen))
+		    return (ip + patlen)
+	}
+
+	return (0)
+end
+
+
+# STRSE1 -- Internal routine which compares a substring of the first string
+# with the pattern string.  STREQ cannot be used because it does not give a
+# match unless the two strings have the same length.
+
+bool procedure strse1 (str, patstr, patlen)
+
+char	str[ARB]
+char	patstr[ARB]
+int	patlen
+int	ip
+
+begin
+	do ip = 1, ARB
+	    if (patstr[ip] == EOS || str[ip] != patstr[ip])
+		break
+
+	patlen = ip - 1
+	return (patstr[ip] == EOS)
+end