Re: crc

[Simon Josefsson]

Ok to install?

Now that I read through the module again, I realize we have the same
'char*' vs 'void*' vs 'uint8_t*' issue here.  To reiterate, 'uint8_t*'
causes problems when sooner or later the type ends up in public header
files.  And 'char*' has the signed/unsigned trouble and the POSIX
assumption for size and encoding.  Finally, 'void*' doesn't have any
obvious drawback, but I think it somewhat bad style.

Perhaps I should work on making the ax_create_stdint.m4 macro part of
gnulib, and change these modules to use uint8_t*?  Applications could
then install the header file generated by ax_create_stdint.m4 to be
able to use uint*_t etc in public header files.  I've used this for a
long time in libidn without problems.  Using uint8_t feels modern
somehow.

Thanks,
Simon

Index: modules/crc
===================================================================
RCS file: modules/crc
diff -N modules/crc
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ modules/crc 8 Oct 2005 08:19:01 -0000
@@ -0,0 +1,24 @@
+Description:
+Compute cyclic redundancy codes.
+
+Files:
+lib/crc.h
+lib/crc.c
+m4/crc.m4
+
+Depends-on:
+stdint
+
+configure.ac:
+gl_CRC
+
+Makefile.am:
+
+Include:
+"crc.h"
+
+License:
+LGPL
+
+Maintainer:
+Simon Josefsson
Index: modules/crc-tests
===================================================================
RCS file: modules/crc-tests
diff -N modules/crc-tests
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ modules/crc-tests   8 Oct 2005 08:19:01 -0000
@@ -0,0 +1,11 @@
+Files:
+tests/test-crc.c
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+TESTS += test-crc
+noinst_PROGRAMS += test-crc
+test_crc_SOURCES = test-crc.c
Index: m4/crc.m4
===================================================================
RCS file: m4/crc.m4
diff -N m4/crc.m4
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ m4/crc.m4   8 Oct 2005 08:19:01 -0000
@@ -0,0 +1,11 @@
+# crc.m4 serial 1
+dnl Copyright (C) 2005 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_CRC],
+[
+  AC_LIBSOURCES([crc.h, crc.c])
+  AC_LIBOBJ([crc])
+])
Index: lib/crc.h
===================================================================
RCS file: lib/crc.h
diff -N lib/crc.h
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ lib/crc.h   8 Oct 2005 08:19:01 -0000
@@ -0,0 +1,53 @@
+/* crc.h -- cyclic redundancy checks
+   Copyright (C) 2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Simon Josefsson.  */
+
+#ifndef CRC_H
+# define CRC_H 1
+
+#include <stddef.h>
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#endif
+#if HAVE_STDINT_H
+# include <stdint.h>
+#endif
+
+/* Compute CRC-32 value of LEN bytes long BUF, and return it. */
+extern uint32_t crc32 (const char *buf, size_t len);
+
+/* Incrementally update CRC-32 value CRC using LEN bytes long BUF.  In
+   the first call, use 0 as the value for CRC.  Return the updated
+   CRC-32 value.  */
+extern uint32_t crc32_update (uint32_t crc, const char *buf, size_t len);
+
+/* Compute modified-CRC-32 value of LEN bytes long BUF, and return it.
+   The "modification" is to avoid the initial and final XOR operation.
+   Due to historic implementation errors, this variant is sometimes
+   used (i.e., in RFC 3961). */
+extern uint32_t crc32_no_xor (const char *buf, size_t len);
+
+/* Incrementally update modified-CRC-32 value CRC using LEN bytes long
+   BUF.  In the first call, use 0 as the value for CRC.  Return the
+   updated modified-CRC-32 value.  The "modification" is to avoid the
+   initial and final XOR operation.  Due to historic implementation
+   errors, this variant is sometimes used (i.e., in RFC 3961).  */
+extern uint32_t
+crc32_update_no_xor (uint32_t crc, const char *buf, size_t len);
+
+#endif /* CRC_H */
Index: lib/crc.c
===================================================================
RCS file: lib/crc.c
diff -N lib/crc.c
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ lib/crc.c   8 Oct 2005 08:19:01 -0000
@@ -0,0 +1,150 @@
+/* crc.c -- cyclic redundancy checks
+   Copyright (C) 2005 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., 51 Franklin Street, Fifth Floor, Boston, MA
+   02110-1301, USA.  */
+
+/* Written by Simon Josefsson.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "crc.h"
+
+/* Table of CRCs of all 8-bit messages.  Generated by running code
+   from RFC 1952 modified to print out the table. */
+static const uint32_t crc32_table[256] = {
+  0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
+  0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
+  0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
+  0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
+  0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+  0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
+  0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
+  0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
+  0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
+  0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+  0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
+  0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
+  0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
+  0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
+  0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+  0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
+  0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
+  0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
+  0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
+  0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+  0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
+  0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
+  0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
+  0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
+  0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+  0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
+  0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
+  0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
+  0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
+  0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+  0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
+  0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
+  0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
+  0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
+  0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+  0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
+  0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
+  0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
+  0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
+  0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+  0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
+  0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
+  0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
+};
+
+/*
+ * The following function was extracted from RFC 1952 by Simon
+ * Josefsson, and modified to avoid initial and final XOR and to use
+ * size_t for the buffer length.  The original copyright and notice
+ * from the document follows:
+ *
+ *    Copyright (c) 1996 L. Peter Deutsch
+ *
+ *    Permission is granted to copy and distribute this document for
+ *    any purpose and without charge, including translations into
+ *    other languages and incorporation into compilations, provided
+ *    that the copyright notice and this notice are preserved, and
+ *    that any substantive changes or deletions from the original are
+ *    clearly marked.
+ *
+ * The copyright on RFCs, and consequently the function below, are
+ * supposedly also retroactively claimed by the Internet Society
+ * (according to address@hidden), with the following
+ * copyright notice:
+ *
+ *    Copyright (C) The Internet Society.  All Rights Reserved.
+ *
+ *    This document and translations of it may be copied and furnished
+ *    to others, and derivative works that comment on or otherwise
+ *    explain it or assist in its implementation may be prepared,
+ *    copied, published and distributed, in whole or in part, without
+ *    restriction of any kind, provided that the above copyright
+ *    notice and this paragraph are included on all such copies and
+ *    derivative works.  However, this document itself may not be
+ *    modified in any way, such as by removing the copyright notice or
+ *    references to the Internet Society or other Internet
+ *    organizations, except as needed for the purpose of developing
+ *    Internet standards in which case the procedures for copyrights
+ *    defined in the Internet Standards process must be followed, or
+ *    as required to translate it into languages other than English.
+ *
+ *    The limited permissions granted above are perpetual and will not be
+ *    revoked by the Internet Society or its successors or assigns.
+ *
+ *    This document and the information contained herein is provided
+ *    on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
+ *    ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
+ *    IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE
+ *    OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY
+ *    IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
+ *    PARTICULAR PURPOSE.
+ *
+ */
+uint32_t
+crc32_update_no_xor (uint32_t crc, const char *buf, size_t len)
+{
+  size_t n;
+
+  for (n = 0; n < len; n++)
+    crc = crc32_table[(crc ^ buf[n]) & 0xff] ^ (crc >> 8);
+
+  return crc;
+}
+
+uint32_t
+crc32_no_xor (const char *buf, size_t len)
+{
+  return crc32_update_no_xor (0L, buf, len);
+}
+
+uint32_t
+crc32_update (uint32_t crc, const char *buf, size_t len)
+{
+  return crc32_update_no_xor (0L ^ 0xffffffffL, buf, len) ^ 0xffffffffL;
+}
+
+uint32_t
+crc32 (const char *buf, size_t len)
+{
+  return crc32_update (0L, buf, len);
+}
Index: tests/test-crc.c
===================================================================
RCS file: tests/test-crc.c
diff -N tests/test-crc.c
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ tests/test-crc.c    8 Oct 2005 08:19:01 -0000
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2005 Free Software Foundation
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.  */
+
+/* Written by Simon Josefsson.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "crc.h"
+
+#include <stdio.h>
+
+int
+main (int argc, char *argv[])
+{
+  uint32_t p;
+
+  p = crc32_update_no_xor (42, "foo", 3);
+  if (p != 0x46e87f05)
+    {
+      printf ("cunx got %lx\n", p);
+      return 1;
+    }
+
+  p = crc32_no_xor ("foo", 3);
+  if (p != 0x7332bc33)
+    {
+      printf ("cnx got %lx\n", p);
+      return 1;
+    }
+
+  p = crc32_update (42, "foo", 3);
+  if (p != 0x8c736521)
+    {
+      printf ("cu got %lx\n", p);
+      return 1;
+    }
+
+  p = crc32 ("foo", 3);
+  if (p != 0x8c736521)
+    {
+      printf ("c got %lx\n", p);
+      return 1;
+    }
+
+  return 0;
+}