Add support for the generic Telechips firmware format checksums - use -tcc=sum if the header just contains a single checksum, or -tcc=crc if the header contains two 32-bit CRCs. Credit goes to Hein-Pieter van Braam for his work on identifying the (reverse) CRC32 algorithm used when calculating the two CRCs

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14917 a1c6a512-1295-4272-9138-f99709370657

5 files changed, 220 insertions, 7 deletions

diff --git a/docs/CREDITS b/docs/CREDITS
index 83967930d8..0f09162eaf 100644
--- a/docs/CREDITS
+++ b/docs/CREDITS
@@ -336,6 +336,7 @@ Alexander Eickhoff
 Pinitnun Shanasabang
 Ken Fazzone
 David Bishop
+Hein-Pieter van Braam
 
 The libmad team
 The wavpack team
diff --git a/tools/Makefile b/tools/Makefile
index 74d82affab..bbb9b0d9b0 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -16,15 +16,16 @@ CLEANALL := scramble descramble iriver sh2d bmp2rb rdf2binary convbdf	\
 all:
         @echo "Run make in your build directory!"
 
-scramble: scramble.o iriver.o mi4.o gigabeat.o gigabeats.o
+scramble: scramble.o iriver.o mi4.o gigabeat.o gigabeats.o telechips.o
 descramble: descramble.o iriver.o gigabeat.o
 
-scramble.o: scramble.c iriver.h mi4.h gigabeat.h
+scramble.o: scramble.c iriver.h mi4.h gigabeat.h telechips.h
 descramble.o: descramble.c iriver.h gigabeat.h
 iriver.o: iriver.c iriver.h
 gigabeat.o: gigabeat.c gigabeat.h
 gigabeats.o: gigabeats.c gigabeats.h
 mi4.o: mi4.c mi4.h
+telechips.o: telechips.c telechips.h
 
 sh2d: sh2d.c
 
diff --git a/tools/scramble.c b/tools/scramble.c
index 8534d41832..ad128835c5 100644
--- a/tools/scramble.c
+++ b/tools/scramble.c
@@ -25,6 +25,7 @@
 #include "gigabeat.h"
 #include "gigabeats.h"
 #include "mi4.h"
+#include "telechips.h"
 
 int iaudio_encode(char *iname, char *oname, char *idstring);
 int ipod_encode(char *iname, char *oname, int fw_ver, bool fake_rsrc);
@@ -102,6 +103,7 @@ void usage(void)
            "\t        -model=XXXX   where XXXX is the model id string\n"
            "\t        -type=XXXX    where XXXX is a string indicating the \n"
            "\t                      type of binary, eg. RBOS, RBBL\n"
+           "\t-tcc=X  Telechips generic firmware format (X values: sum, crc)\n"
            "\t-add=X  Rockbox generic \"add-up\" checksum format\n"
            "\t        (X values: h100, h120, h140, h300, ipco, nano, ipvd, mn2g\n"
            "\t                   ip3g, ip4g, mini, iax5, h10, h10_5gb, tpj2,\n"
@@ -127,7 +129,7 @@ int main (int argc, char** argv)
     unsigned long modelnum;
     char modelname[5];
     int model_id;
-    enum { none, scramble, xor, add } method = scramble;
+    enum { none, scramble, xor, tcc_sum, tcc_crc, add } method = scramble;
 
     model_id = ARCHOS_PLAYER;
     
@@ -186,6 +188,20 @@ int main (int argc, char** argv)
             return -1;
         }
     }
+    else if(!strncmp(argv[1], "-tcc=", 4)) {
+        headerlen = 0;
+        iname = argv[2];
+        oname = argv[3];
+
+        if(!strcmp(&argv[1][5], "sum"))
+            method = tcc_sum;
+        else if(!strcmp(&argv[1][5], "crc"))
+            method = tcc_crc;
+        else {
+            fprintf(stderr, "unsupported TCC method: %s\n", &argv[1][5]);
+            return 2;
+        }
+    }
     else if(!strncmp(argv[1], "-add=", 5)) {
         iname = argv[2];
         oname = argv[3];
@@ -409,7 +425,7 @@ int main (int argc, char** argv)
             break;
     }
 
-    if(method != add) {
+    if((method == none) || (method == scramble) || (method == xor)) {
         /* calculate checksum */
         for (i=0;i<length;i++)
             crc += inbuf[i];
@@ -426,6 +442,17 @@ int main (int argc, char** argv)
             headerlen = 8;
         }
         break;
+
+        case tcc_sum:
+            memcpy(outbuf, inbuf, length); /* the input buffer to output*/
+            telechips_encode_sum(outbuf, length);
+            break;
+
+        case tcc_crc:
+            memcpy(outbuf, inbuf, length); /* the input buffer to output*/
+            telechips_encode_crc(outbuf, length);
+            break;
+
         case scramble:
             if (headerlen == 6) {
                 int2be(length, header);
@@ -488,9 +515,11 @@ int main (int argc, char** argv)
        perror(oname);
        return -1;
     }
-    if ( !fwrite(header,headerlen,1,file) ) {
-       perror(oname);
-       return -1;
+    if (headerlen > 0) {
+       if ( !fwrite(header,headerlen,1,file) ) {
+          perror(oname);
+          return -1;
+       }
     }
     if ( !fwrite(outbuf,length,1,file) ) {
        perror(oname);
diff --git a/tools/telechips.c b/tools/telechips.c
new file mode 100644
index 0000000000..5b6f3c23b3
--- /dev/null
+++ b/tools/telechips.c
@@ -0,0 +1,156 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Telechips firmware checksum support for scramble
+ *
+ * Copyright (C) 2007 Dave Chapman
+ *
+ * Thanks to Hein-Pieter van Braam for his work in identifying the
+ * CRC algorithm used.
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+static uint32_t crctable[256];
+
+/* Simple implementation of a function to reverse the bottom n bits in x */
+static uint32_t bitreverse(uint32_t x,int n)
+{
+    int i;
+    uint32_t mask = 1<<(n-1);
+    uint32_t res = 0;
+
+    for (i=0; i<n; i++)
+    {
+        if (x & 1)
+            res |=  mask;
+
+        x >>= 1;
+        mask >>= 1;
+    }
+    return res;
+}
+
+/* Generate a lookup table for a reverse CRC32 */
+static void gentable(uint32_t poly)
+{
+    int i;
+    uint32_t r;
+    uint32_t index;
+
+    for (index = 0; index < 256; index++)
+    {
+        r = bitreverse(index,8) << 24;
+        for (i=0; i<8; i++)
+        {
+            if (r & (1 << 31))
+                r = (r << 1) ^ poly;
+            else
+                r<<=1;
+        }
+        crctable[index] = bitreverse(r,32);
+    }
+}
+
+/* Perform a reverse CRC32 */
+static uint32_t calc_crc(unsigned char *message, int size)
+{
+    uint32_t crc = 0;
+    int i;
+
+    for (i=0; i < size; i++){
+        if ((i < 0x10) || (i >= 0x18)) {
+            crc = crctable[((crc ^ (message[i])) & 0xff)] ^ (crc >> 8);
+        }
+    }
+
+    return crc;
+}
+
+/* Endian-safe functions to read/write a 32-bit little-endian integer */
+
+static uint32_t get_uint32le(unsigned char* p)
+{
+    return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
+}
+
+static void put_uint32le(unsigned char* p, uint32_t x)
+{
+    p[0] = x & 0xff;
+    p[1] = (x >> 8) & 0xff;
+    p[2] = (x >> 16) & 0xff;
+    p[3] = (x >> 24) & 0xff;
+}
+
+/* A simple checksum - seems to be used by the TCC76x firmwares */
+void telechips_encode_sum(unsigned char* buf, int length)
+{
+    uint32_t sum;
+    int i;
+
+    /* Set checksum field to 0 */
+    put_uint32le(buf + 0x10, 0);
+
+    /* Perform a simple sum, treating the file as a series of 32-bit
+       little-endian integers */
+    sum = 0;
+    for (i=0; i < length; i+=4) {
+        sum += get_uint32le(buf + i);
+    }
+    /* Negate the sum - this means that the sum of the whole file
+       (including this value) will be equal to zero */
+    sum = -sum;
+
+    /* Set the checksum field */
+    put_uint32le(buf + 0x10, sum);
+}
+
+
+/* Two reverse CRC32 checksums - seems to be used by the TCC77x firmwares */
+void telechips_encode_crc(unsigned char* buf, int length)
+{
+    uint32_t crc1,crc2;
+
+    /* Generate the CRC table */
+    gentable(0x8001801BL);
+
+    /* Clear the existing CRC values */
+    put_uint32le(buf+0x10, 0);
+    put_uint32le(buf+0x18, 0);
+
+    /* Write the length */
+    put_uint32le(buf+0x1c, length);
+
+    /* Calculate the first CRC - over the entire file */
+    crc1 = calc_crc(buf, length);
+
+    /* What happens next depends on the filesize */
+    if (length >= 128*1024)
+    {
+        put_uint32le(buf+0x18, crc1);
+
+        crc2 = calc_crc(buf, 128*1024);
+        put_uint32le(buf+0x10, crc2);
+    } else {
+        put_uint32le(buf+0x10, crc1);
+    }
+}
diff --git a/tools/telechips.h b/tools/telechips.h
new file mode 100644
index 0000000000..7854da0294
--- /dev/null
+++ b/tools/telechips.h
@@ -0,0 +1,26 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2007 Dave Chapman
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#ifndef _TELECHIPS_H
+#define _TELECHIPS_H
+
+void telechips_encode_sum(unsigned char* buf, int length);
+void telechips_encode_crc(unsigned char* buf, int length);
+
+#endif