1 files changed, 48 insertions, 0 deletions
diff --git a/lib/memcasecmp.c b/lib/memcasecmp.c
new file mode 100644
index 0000000..6e02c25
--- /dev/null
+++ b/lib/memcasecmp.c
@@ -0,0 +1,48 @@
+/* Case-insensitive buffer comparator.
+   Copyright (C) 1996-1997, 2000, 2003, 2006, 2009-2022 Free Software
+   Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Jim Meyering.  */
+
+#include <config.h>
+
+#include "memcasecmp.h"
+
+#include <ctype.h>
+#include <limits.h>
+
+/* Like memcmp, but ignore differences in case.
+   Convert to upper case (not lower) before comparing so that
+   join -i works with sort -f.  */
+
+int
+memcasecmp (const void *vs1, const void *vs2, size_t n)
+{
+  size_t i;
+  char const *s1 = vs1;
+  char const *s2 = vs2;
+  for (i = 0; i < n; i++)
+    {
+      unsigned char u1 = s1[i];
+      unsigned char u2 = s2[i];
+      int U1 = toupper (u1);
+      int U2 = toupper (u2);
+      int diff = (UCHAR_MAX <= INT_MAX ? U1 - U2 : _GL_CMP (U1, U2));
+      if (diff)
+        return diff;
+    }
+  return 0;
+}