crc: Add a utility to compute the CRC of a frame

The discom-crc utility computes the CRC of a frame using the same
algorithm as the DISCOM hardware block. This is useful to precompute CRC
values and then compare them with the hardware-generated values.

The utility computes the CRC on data stored in a file passed as a
command line argument. It supports two optional arguments, --crop and
--size, to specify the crop rectangle and the image size. The size only
needs to be specified if a crop rectangle is set, it is deduced from the
file size otherwise.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/crc/gen-crc.py b/crc/gen-crc.py
new file mode 100755
index 0000000..10c5776
--- /dev/null
+++ b/crc/gen-crc.py
@@ -0,0 +1,14 @@
+#!/usr/bin/python3
+# SPDX-License-Identifier: GPL-2.0-or-later
+# SPDX-FileCopyrightText: 2020 Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+
+import crcmod
+import sys
+
+# The initial value is ignored, it must instead be passed to the generated C
+# function.
+crc = crcmod.Crc(0x104c11db7, 0xffffffff, True, 0xffffffff)
+
+f = open(sys.argv[1], 'w')
+crc.generateCode('calculate_crc', f, 'uint8_t', 'uint32_t')
+f.close()