--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libnumdb2/check_short.c	Mon Aug 14 14:16:07 2023 -0800
@@ -0,0 +1,36 @@
+/*
+ * The library function implemented in this module looks up 4-digit short
+ * dialing numbers in ThemWi number db to determine their disposition.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include "../include/number_db_v2.h"
+
+extern struct numdb_file_hdr numdb_hdr;
+extern struct short_number_rec *numdb_short_numbers;
+
+static int
+compare_short_num(p1, p2)
+	uint16_t *p1, *p2;
+{
+	if (*p1 < *p2)
+		return(-1);
+	if (*p1 > *p2)
+		return(1);
+	return(0);
+}
+
+struct short_number_rec *
+numdb_lookup_short(numstr)
+	char *numstr;
+{
+	uint16_t key;
+
+	if (!numdb_short_numbers || !numdb_hdr.short_number_count)
+		return(0);
+	key = digits4_to_uint16(numstr);
+	return bsearch(&key, numdb_short_numbers, numdb_hdr.short_number_count,
+			sizeof(struct short_number_rec), compare_short_num);
+}