On 2006-08-07, David Peters <[email protected]> wrote:
> Is it possible for the GCC tools to generate a
> checksum from the generated code and embed it into the
> hex file at a specific address?
I don't think so.
It's fairly trivial to write a little utility to do that,
though. There are also tons of pretty fancy (and free) hex
file utilities that do that sort of thing.
For exampmle, here's a Python program I use to pad a file to a
specified size (by adding 0xffs to the input file) and add a
16-bit checksum to the last two bytes:
------------------------------8<------------------------------
#!/usr/bin/python
import sys
def showHex(s):
print " ".join(["%02x" % ord(c) for c in s])
def sum16(s):
sum = 0
i = 0
while i < len(s):
sum += ord(s[i])<<8
sum += ord(s[i+1])
sum &= 0xffff
i += 2
return sum
requiredSize = int(sys.argv[1])*1024
inputFilename = sys.argv[2]
outputFilename = sys.argv[3]
image = file(inputFilename,"rb").read()
print len(image)
padLength = (requiredSize-4) - len(image)
image += '\xff'*padLength
print len(image)
s = sum16(image)
c = -s & 0xffff
print hex(s),hex(c)
if c == 0 or c == 0xffff:
c -= 0x1234
c &= 0xffff
image += '\x12\x34'
else:
image += '\x00\x00'
image += (chr(c>>8) + chr(c&0xff))
file(outputFilename,"wb").write(image)
------------------------------8<------------------------------
The above program operates on binary files (which are much
easier to manipulate than hex files). If you really want a hex
file when you're done, the objcopy utility can convert between
binary and various hex formats.
> I've done this in the past using the IAR compiler and need it
> for the bootloader to check the new code being loaded into
> flash.
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