From 80055c2cdc1a5376c609e50f3ae0710f27146b15 Mon Sep 17 00:00:00 2001
From: Damien George <damien@micropython.org>
Date: Tue, 22 Mar 2022 11:42:52 +1100
Subject: [PATCH] stm32/mboot/fwupdate.py: Simplify calculation of CRC32.

Signed-off-by: Damien George <damien@micropython.org>
---
 ports/stm32/mboot/fwupdate.py | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/ports/stm32/mboot/fwupdate.py b/ports/stm32/mboot/fwupdate.py
index df1ff62846..3e25351370 100644
--- a/ports/stm32/mboot/fwupdate.py
+++ b/ports/stm32/mboot/fwupdate.py
@@ -75,12 +75,10 @@ def dfu_read(filename):
         return None
 
     hdr = f.read(16)
-    crc = crc32(hdr[:-4], crc)
-    hdr = struct.unpack("<HHHH3sBI", hdr)
-
+    crc = crc32(hdr, crc)
     crc = ~crc & 0xFFFFFFFF
-    if crc != hdr[-1]:
-        print("CRC failed", crc, hdr[-1])
+    if crc != 0:
+        print("CRC failed", crc)
         return None
 
     return elems