in preparation for de-pluginising h223, move golay code support into libwireshark

svn path=/trunk/; revision=22603

4 files changed, 2 insertions, 310 deletions

diff --git a/plugins/h223/Makefile.common b/plugins/h223/Makefile.common
index c691c816a0..e91459d44c 100644
--- a/plugins/h223/Makefile.common
+++ b/plugins/h223/Makefile.common
@@ -33,12 +33,10 @@ DISSECTOR_SRC = \
 
 # corresponding headers
 DISSECTOR_INCLUDES =	\
-	golay.h \
 	packet-h223.h \
 	packet-srp.h
 
 # Dissector helpers.  They're included in the source files in this
 # directory, but they're not dissectors themselves, i.e. they're not
 # used to generate "register.c").
-DISSECTOR_SUPPORT_SRC =	\
-	golay.c
+DISSECTOR_SUPPORT_SRC =
diff --git a/plugins/h223/golay.c b/plugins/h223/golay.c
deleted file mode 100644
index 3de2062269..0000000000
--- a/plugins/h223/golay.c
+++ /dev/null
@@ -1,257 +0,0 @@
-/* $Id$
- *
- * Provides routines for encoding and decoding the extended Golay
- * (24,12,8) code.
- *
- * This implementation will detect up to 4 errors in a codeword (without
- * being able to correct them); it will correct up to 3 errors.
- *
- * Wireshark - Network traffic analyzer
- * By Gerald Combs <gerald@wireshark.org>
- * Copyright 1998 Gerald Combs
- *
- * 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
- * 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, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
- */
-
-#include <glib.h>
-#include "golay.h"
-
-
-/* Encoding matrix, H
-
-   These entries are formed from the matrix specified in H.223/B.3.2.1.3;
-   it's first transposed so we have:
-
-   [P1 ]   [111110010010]  [MC1 ]
-   [P2 ]   [011111001001]  [MC2 ]
-   [P3 ]   [110001110110]  [MC3 ]
-   [P4 ]   [011000111011]  [MC4 ]
-   [P5 ]   [110010001111]  [MPL1]
-   [P6 ] = [100111010101]  [MPL2]
-   [P7 ]   [101101111000]  [MPL3]
-   [P8 ]   [010110111100]  [MPL4]
-   [P9 ]   [001011011110]  [MPL5]
-   [P10]   [000101101111]  [MPL6]
-   [P11]   [111100100101]  [MPL7]
-   [P12]   [101011100011]  [MPL8]
-
-   So according to the equation, P1 = MC1+MC2+MC3+MC4+MPL1+MPL4+MPL7
-
-   Looking down the first column, we see that if MC1 is set, we toggle bits
-   1,3,5,6,7,11,12 of the parity: in binary, 110001110101 = 0xE3A
-
-   Similarly, to calculate the inverse, we read across the top of the table and
-   see that P1 is affected by bits MC1,MC2,MC3,MC4,MPL1,MPL4,MPL7: in binary,
-   111110010010 = 0x49F.
-
-   I've seen cunning implementations of this which only use one table. That
-   technique doesn't seem to work with these numbers though.
-*/
-
-static const guint golay_encode_matrix[12] = {
-    0xC75,
-    0x49F,
-    0xD4B,
-    0x6E3,
-    0x9B3,
-    0xB66,
-    0xECC,
-    0x1ED,
-    0x3DA,
-    0x7B4,
-    0xB1D,
-    0xE3A,
-};
-
-static const guint golay_decode_matrix[12] = {
-   0x49F,
-   0x93E,
-   0x6E3,
-   0xDC6,
-   0xF13,
-   0xAB9,
-   0x1ED,
-   0x3DA,
-   0x7B4,
-   0xF68,
-   0xA4F,
-   0xC75,
-};
-
-
-
-/* Function to compute the Hamming weight of a 12-bit integer */
-static guint weight12(guint vector)
-{
-    guint w=0;
-    guint i;
-    for( i=0; i<12; i++ )
-	if( vector & 1<<i )
-	    w++;
-    return w;
-}
-
-/* returns the golay coding of the given 12-bit word */
-static guint golay_coding(guint w)
-{
-    guint out=0;
-    guint i;
-
-    for( i = 0; i<12; i++ ) {
-	if( w & 1<<i )
-	    out ^= golay_encode_matrix[i];
-    }
-    return out;
-}
-
-/* encodes a 12-bit word to a 24-bit codeword */
-guint32 golay_encode(guint w)
-{
-    return ((guint32)w) | ((guint32)golay_coding(w))<<12;
-}
-
-
-
-/* returns the golay coding of the given 12-bit word */
-static guint golay_decoding(guint w)
-{
-    guint out=0;
-    guint i;
-
-    for( i = 0; i<12; i++ ) {
-	if( w & 1<<(i) )
-	    out ^= golay_decode_matrix[i];
-    }
-    return out;
-}
-
-
-/* return a mask showing the bits which are in error in a received
- * 24-bit codeword, or -1 if 4 errors were detected.
- */
-gint32 golay_errors(guint32 codeword)
-{
-    guint received_data, received_parity;
-    guint syndrome;
-    guint w,i;
-    guint inv_syndrome = 0;
-
-    received_parity = (guint)(codeword>>12);
-    received_data   = (guint)codeword & 0xfff;
-
-    /* We use the C notation ^ for XOR to represent addition modulo 2.
-     *
-     * Model the received codeword (r) as the transmitted codeword (u)
-     * plus an error vector (e).
-     *
-     *   r = e ^ u
-     *
-     * Then we calculate a syndrome (s):
-     *
-     *   s = r * H, where H = [ P   ], where I12 is the identity matrix
-     *                        [ I12 ]
-     *
-     * (In other words, we calculate the parity check for the received
-     * data bits, and add them to the received parity bits)
-     */
-
-    syndrome = received_parity ^ (golay_coding(received_data));
-    w = weight12(syndrome);
-    
-    /*
-     * The properties of the golay code are such that the Hamming distance (ie,
-     * the minimum distance between codewords) is 8; that means that one bit of
-     * error in the data bits will cause 7 errors in the parity bits.
-     *
-     * In particular, if we find 3 or fewer errors in the parity bits, either:
-     *  - there are no errors in the data bits, or
-     *  - there are at least 5 errors in the data bits
-     * we hope for the former (we don't profess to deal with the
-     * latter).
-     */
-    if( w <= 3 ) {
-	return ((gint32) syndrome)<<12;
-    }
-    
-    /* the next thing to try is one error in the data bits.
-     * we try each bit in turn and see if an error in that bit would have given
-     * us anything like the parity bits we got. At this point, we tolerate two
-     * errors in the parity bits, but three or more errors would give a total
-     * error weight of 4 or more, which means it's actually uncorrectable or
-     * closer to another codeword. */
-     
-    for( i = 0; i<12; i++ ) {
-	guint error = 1<<i;
-	guint coding_error = golay_encode_matrix[i];
-	if( weight12(syndrome^coding_error) <= 2 ) {
-	    return (gint32)((((guint32)(syndrome^coding_error))<<12) | (guint32)error) ;
-	}
-    }
-
-    /* okay then, let's see whether the parity bits are error free, and all the
-     * errors are in the data bits. model this as follows:
-     *
-     * [r | pr] = [u | pu] + [e | 0]
-     *
-     * pr = pu
-     * pu = H * u => u = H' * pu = H' * pr , where H' is inverse of H
-     *
-     * we already have s = H*r + pr, so pr = s - H*r = s ^ H*r
-     * e = u ^ r
-     *   = (H' * ( s ^ H*r )) ^ r
-     *   = H'*s ^ r ^ r
-     *   = H'*s
-     *
-     * Once again, we accept up to three error bits...
-     */
-
-    inv_syndrome = golay_decoding(syndrome);
-    w = weight12(inv_syndrome);
-    if( w <=3 ) {
-	return (gint32)inv_syndrome;
-    }
-
-    /* Final shot: try with 2 errors in the data bits, and 1 in the parity
-     * bits; as before we try each of the bits in the parity in turn */
-    for( i = 0; i<12; i++ ) {
-	guint error = 1<<i;
-	guint coding_error = golay_decode_matrix[i];
-	if( weight12(inv_syndrome^coding_error) <= 2 ) {
-	    guint32 error_word = ((guint32)(inv_syndrome^coding_error)) | ((guint32)error)<<12;
-	    return (gint32)error_word;
-	}
-    }
-
-    /* uncorrectable error */
-    return -1;
-}
-    
-
-
-/* decode a received codeword. Up to 3 errors are corrected for; 4
-   errors are detected as uncorrectable (return -1); 5 or more errors
-   cause an incorrect correction.
-*/
-gint golay_decode(guint32 w)
-{
-    guint data = (guint)w & 0xfff;
-    gint32 errors = golay_errors(w);
-    guint data_errors;
-    
-    if( errors == -1 )
-	return -1;
-    data_errors = (guint)errors & 0xfff;
-    return (gint)(data ^ data_errors);
-}
diff --git a/plugins/h223/golay.h b/plugins/h223/golay.h
deleted file mode 100644
index 1a6e7994a8..0000000000
--- a/plugins/h223/golay.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/* $Id$
- *
- * Provides routines for encoding and decoding the extended Golay
- * (24,12,8) code.
- *
- * This implementation will detect up to 4 errors in a codeword (without
- * being able to correct them); it will correct up to 3 errors.
- *
- * We use guint32s to hold the 24-bit codewords, with the data part in
- * the bottom 12 bits and the parity in bits 12-23.
- *
- *
- * Wireshark - Network traffic analyzer
- * By Gerald Combs <gerald@wireshark.org>
- * Copyright 1998 Gerald Combs
- *
- * 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
- * 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, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
- */
-#ifndef __GOLAY_H__
-#define __GOLAY_H__
-
-/* encodes a 12-bit word to a 24-bit codeword
- */
-guint32 golay_encode(guint w);
-
-/* return a mask showing the bits which are in error in a received
- * 24-bit codeword, or -1 if 4 errors were detected.
- */
-gint32 golay_errors(guint32 codeword);
-
-/* decode a received codeword. Up to 3 errors are corrected for; 4
-   errors are detected as uncorrectable (return -1); 5 or more errors
-   cause an incorrect correction.
-*/
-gint golay_decode(guint32 w);
-
-#endif
diff --git a/plugins/h223/packet-h223.c b/plugins/h223/packet-h223.c
index 3060be0989..2cd86d7fe4 100644
--- a/plugins/h223/packet-h223.c
+++ b/plugins/h223/packet-h223.c
@@ -38,13 +38,13 @@
 #include <epan/packet.h>
 #include <epan/stream.h>
 #include <epan/reassemble.h>
+#include <epan/golay.h>
 #include <epan/iax2_codec_type.h>
 #include <epan/dissectors/packet-frame.h>
 #include <epan/asn1.h>
 #include <epan/dissectors/packet-h245.h>
 
 #include "packet-h223.h"
-#include "golay.h"
 
 #include <string.h>