Fix calculation of ISO-TP SF size field length #56
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Given the following setup: * CAN-FD bus * tx_data_length = 64 * extended addressing When sending a 7 byte payload, the full ISO-TP frame with size and address fields would have a minimum size of 7 + 1 (addr) + 1 (size) = 9. According to the standard, such a payload must use a two-byte size field. However, the current implementation does not correctly calculate the length of the size field. This commit fixes the calculation and introduces a unit test to verify the correct behavior.
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Thank you very much for this. That's a good catch. high quality pull request. Merging right away. |
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Given the following setup:
When sending a 7 byte payload, the full ISO-TP frame with size and address fields would have a minimum size of
7 (data) + 1 (addr) + 1 (header + size field) = 9. According to the standard, when receiving a CAN frame with a data length of >8 byte, the size field must have a length of 12 bit and the first four bits must be equal to 0. However, the current implementation does not correctly calculate the length of the size field and uses only four bits.In the patch, I updated the size field length calculation to what I would assume to be correct. I also added a unit test to verify the correct behavior.