X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/b7580524f33ee21d3ddc49fe36a71e107e87df1b..ff1e93acf2626d2531a97de3b54bce9b5a37bcb5:/crc-mktab.c

diff --git a/crc-mktab.c b/crc-mktab.c
index 887315b..200ed32 100644
--- a/crc-mktab.c
+++ b/crc-mktab.c
@@ -1,13 +1,13 @@
 /* -*-c-*-
  *
- * $Id: crc-mktab.c,v 1.1 2000/07/21 19:01:33 mdw Exp $
+ * $Id: crc-mktab.c,v 1.6 2004/04/08 01:36:11 mdw Exp $
  *
  * Build CRC tables
  *
  * (c) 2000 Straylight/Edgeware
  */
 
-/*----- Licensing notice --------------------------------------------------* 
+/*----- Licensing notice --------------------------------------------------*
  *
  * This file is part of the mLib utilities library.
  *
@@ -15,28 +15,22 @@
  * it under the terms of the GNU Library General Public License as
  * published by the Free Software Foundation; either version 2 of the
  * License, or (at your option) any later version.
- * 
+ *
  * mLib 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 Library General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU Library General Public
  * License along with mLib; if not, write to the Free
  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: crc-mktab.c,v $
- * Revision 1.1  2000/07/21 19:01:33  mdw
- * Generate the CRC table rather than hardcoding it.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
+#include "config.h"
+
 #include <ctype.h>
 #include <errno.h>
 #include <limits.h>
@@ -62,11 +56,9 @@ static const char *type = 0;
 static const char *inc = 0;
 static FILE *fp;
 
-enum {
-  f_bogus = 1,
-  f_ctab = 2,
-  f_reverse = 4
-};
+#define f_bogus 1u
+#define f_ctab 2u
+#define f_reverse 4u
 
 #define BSCOL 72
 
@@ -89,7 +81,8 @@ static void version(FILE *fp)
 
 static void usage(FILE *fp)
 {
-  pquis(fp, "Usage: $ [-cr] [-g guard] [-o file] [-b bits] [-p poly]\n");
+  pquis(fp, "Usage: $ [-cr] [-o FILE] [-g GUARD] [-s SYM] [-i HEADER]\n\
+	[-t TYPE] [-b BITS] [-B BITS] [-p POLY]\n");
 }
 
 static void help(FILE *fp)
@@ -111,7 +104,8 @@ of options are provided:\n\
 -p, --polynomial=POLY	Use the POLY as the dividing polynomial.\n\
 -r, --reverse		Create a `reversed' CRC table.\n\
 -g, --guard=GUARD	Use GUARD as a multiple-inclusion guard constant.\n\
--s, --symbol=SYM	Name the generated table SYM\n\
+-i, --include=HEADER	Include HEADER at top of C source file.\n\
+-s, --symbol=SYM	Name the generated table SYM.\n\
 -t, --type=TYPE		Give the table entries type TYPE in C source.\n\
 -o, --output=FILE	Write the output to FILE.\n\
 ", stdout);
@@ -231,11 +225,13 @@ int main(int argc, char *argv[])
 	  poly = 0x1021;
 	break;
       case 32:
-      case 0:
 	poly = 0x04c11db7;
 	flags |= f_reverse;
 	bits = 32;
 	break;
+      case 0:
+	die(EXIT_FAILURE, "no polynomial or bit width set");
+	break;
       default:
 	die(EXIT_FAILURE, "no standard polynomials for %u bits", bits);
 	break;
@@ -249,7 +245,7 @@ int main(int argc, char *argv[])
       bits += 8;
     }
   }
-  nw = bits/4;
+  nw = (bits + 3)/4;
 
   if ((flags & f_ctab) && !type)
     type = bits > 16 ? "unsigned long" : "unsigned short";
@@ -267,7 +263,7 @@ int main(int argc, char *argv[])
       guard = p;
       for (q = file; *q; p++, q++) {
 	if (isalnum((unsigned char)*q))
-	  *p = *q;
+	  *p = toupper((unsigned char)*q);
 	else
 	  *p = '_';
       }
@@ -312,23 +308,36 @@ int main(int argc, char *argv[])
   while (2 + n * (nw + 4) < BSCOL)
     n <<= 1;
   n >>= 1;
+  max = 1 << chunk;
+  if (n > max)
+    n = max;
   t = 0;
   while (((1 + n * (nw + 4)) & ~7) + 8 * t < BSCOL)
     t++;
 
   /* --- Start grinding --- */
 
-  max = 1 << chunk;
   mask = 0xffffffff >> (32 - bits);
   fputc(' ', fp);
   for (i = 0; i < max; i++) {
-    unsigned long x;
+    unsigned long x, y, z;
     unsigned j;
-
-    x = reflect(i, chunk) << (bits - chunk);
-    for (j = 0; j < chunk; j++)
-      x = ((x << 1) ^ (x & (1 << (bits - 1)) ? poly : 0)) & mask;
-    x = reflect(x, bits);
+    unsigned ni, nn;
+
+    x = reflect(i, chunk);
+    y = 0;
+    nn = chunk;
+    while (nn) {
+      ni = bits;
+      if (ni > nn)
+	ni = nn;
+      z = (x >> (nn - ni)) & (0xffffffff >> (32 - ni));
+      y ^= z << (bits - ni);
+      for (j = 0; j < ni; j++)
+	y = ((y << 1) ^ (y & (1 << (bits - 1)) ? poly : 0)) & mask;
+      nn -= ni;
+    }
+    x = reflect(y, bits);
 
     fprintf(fp, " 0x%0*lx", nw, x);
     if (i == max - 1) {