Diff: tools/patch.py

Revision:

0:f269e3021894

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/patch.py	Sun Oct 23 15:10:02 2016 +0000
@@ -0,0 +1,50 @@
+"""
+mbed SDK
+Copyright (c) 2011-2013 ARM Limited
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+
+http://www.nxp.com/documents/user_manual/UM10360.pdf
+
+32.3.1.1 Criterion for Valid User Code
+The reserved Cortex-M3 exception vector location 7 (offset 0x1C in the vector table)
+should contain the 2's complement of the check-sum of table entries 0 through 6. This
+causes the checksum of the first 8 table entries to be 0. The boot loader code checksums
+the first 8 locations in sector 0 of the flash. If the result is 0, then execution control is
+transferred to the user code.
+"""
+from struct import unpack, pack
+
+
+def patch(bin_path):
+    with open(bin_path, 'r+b') as bin:
+        # Read entries 0 through 6 (Little Endian 32bits words)
+        vector = [unpack('<I', bin.read(4))[0] for _ in range(7)]
+
+        # location 7 (offset 0x1C in the vector table) should contain the 2's
+        # complement of the check-sum of table entries 0 through 6
+        bin.seek(0x1C)
+        bin.write(pack('<I', (~sum(vector) + 1) & 0xFFFFFFFF))
+
+
+def is_patched(bin_path):
+    with open(bin_path, 'rb') as bin:
+        # The checksum of the first 8 table entries should be 0
+        return (sum([unpack('<I', bin.read(4))[0] for _ in range(8)]) & 0xFFFFFFFF) == 0
+
+
+if __name__ == '__main__':
+    bin_path = "C:/Users/emimon01/releases/emilmont/build/test/LPC1768/ARM/MBED_A1/basic.bin"
+    patch(bin_path)
+    assert is_patched(bin_path), "The file is not patched"