1 files changed, 156 insertions, 0 deletions

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);
+    }
+}