1 files changed, 43 insertions, 0 deletions
diff --git a/sys/fmtio/stridxs.x b/sys/fmtio/stridxs.x
new file mode 100644
index 00000000..fef58806
--- /dev/null
+++ b/sys/fmtio/stridxs.x
@@ -0,0 +1,43 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+define	BIGSET		10
+define	SZ_ASCII	128
+
+# STRIDXS -- Return the index of the first occurrence of any of a set of
+# characters in a string.
+
+int procedure stridxs (set, str)
+
+char	set[ARB]		# set of characters to be searched for
+char	str[ARB]		# string to be searched
+
+int	setlen, ip, i
+char	ch, lut[SZ_ASCII]
+int	strlen()
+
+begin
+	setlen = strlen (set)
+
+	if (setlen > BIGSET) {
+	    # Encode the set in a lookup table.
+	    call aclrc (lut, SZ_ASCII)
+	    do i = 1, setlen
+		lut[set[i]] = 1
+
+	    # Search the string.
+	    for (ip=1;  str[ip] != EOS;  ip=ip+1)
+		if (lut[str[ip]] != 0)
+		    return (ip)
+
+	} else {
+	    # Set is too small to be worth using a lookup table.
+	    for (ip=1;  str[ip] != EOS;  ip=ip+1) {
+		ch = str[ip]
+		do i = 1, setlen
+		    if (ch == set[i])
+			return (ip)
+	    }
+	}
+	
+	return (0)
+end