tweak comments

[gnulib.git] / lib / memcasecmp.c

diff --git a/lib/memcasecmp.c b/lib/memcasecmp.c
index 5479028..a2e42e8 100644 (file)
--- a/lib/memcasecmp.c
+++ b/lib/memcasecmp.c
@@ -1,3 +1,22 @@
+/* Case-insensitive buffer comparator.
+   Copyright (C) 1996, 1997 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 2, 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, write to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+/* Jim Meyering (meyering@na-net.ornl.gov) */
+
 #ifdef HAVE_CONFIG_H
 # include <config.h>
 #endif
@@ -5,18 +24,30 @@
 #include <sys/types.h>
 #include <ctype.h>
 
+#if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
+# define IN_CTYPE_DOMAIN(c) 1
+#else
+# define IN_CTYPE_DOMAIN(c) isascii(c)
+#endif
+#define ISLOWER(c) (IN_CTYPE_DOMAIN (c) && islower (c))
+
 #if _LIBC || STDC_HEADERS
-# define TOLOWER(c) tolower (c)
+# define TOUPPER(c) toupper (c)
 #else
-# define TOLOWER(c) (ISUPPER (c) ? tolower (c) : (c))
+# define TOUPPER(c) (ISLOWER (c) ? toupper (c) : (c))
 #endif
 
 #include "memcasecmp.h"
 
-/* Like memcmp, but ignore differences in case.  */
+/* 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)
+memcasecmp (vs1, vs2, n)
+     const void *vs1;
+     const void *vs2;
+     size_t n;
 {
   unsigned int i;
   unsigned char *s1 = (unsigned char *) vs1;
@@ -25,8 +56,8 @@ memcasecmp (const void *vs1, const void *vs2, size_t n)
     {
       unsigned char u1 = *s1++;
       unsigned char u2 = *s2++;
-      if (TOLOWER (u1) != TOLOWER (u2))
-        return TOLOWER (u1) - TOLOWER (u2);
+      if (TOUPPER (u1) != TOUPPER (u2))
+        return TOUPPER (u1) - TOUPPER (u2);
     }
   return 0;
 }