CRC calculation of Virtex 4 bitstream

hi. i have to calculate the crc checksums of a virtex 4 bitstream. there are two ckecksums: one direct after the configuration frames and one at the end of the bitstream. no i want to know, if all bytes are used to generate the checksum? i already implemented the an algorithm, whch works fine with an test input. but when i try to recalculate a checksum of a bitfile, it does not match ... the algorithm i use is from rocksoft:

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i use it with the parameters for crc32: Poly : 04C11DB7 initial value 0xFFFFFFFF input is reflected checksum reflected on end of generation checksum xored with FFFFFFFF

maybe you can help me.

Reply to
lembke.stefan
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Reply to
Mike Treseler

i have already implemented an algorithm, which calculates a checksum from given data. and it works correct.

virtex4 configuration guide: As the configuration data frames are loaded, the device calculates a Cyclic Redundancy Check (CRC) value from the configuration data packets.

i extracted these configuration data frames from the bit file and calculated the checksum of it, once with my implemented algorithm and once with an external program (CrcSfv 1.3) and both checksums are the same, but they are not the ckecksum, which is written down in the bit file.

has anyone an idea, why?

Reply to
lembke.stefan

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