y-modem protocol issue

Hi all,

just to inform, seems xyzModem is not following the protocol spec of YModem:

YMODEM Batch Transmission Session (1 file)

SENDER RECEIVER

                                        <-- C (command:rb)
SOH 00 FF foo.c NUL[123] CRC CRC        -->
                                        <-- ACK
                                        <-- C
SOH 01 FE Data[128] CRC CRC             -->
                                        <-- ACK
SOH 02 FC Data[128] CRC CRC             -->
                                        <-- ACK
SOH 03 FB Data[100] CPMEOF[28] CRC CRC  -->
                                        <-- ACK
EOT                                     -->
                                        <-- NAK
EOT                                     -->
                                        <-- ACK
                                        <-- C
SOH 00 FF NUL[128] CRC CRC              -->
                                        <-- ACK

After first EOT u-boot send an ACK, not correct.
Same behavior using SOH or STX.

Regards
angelo

Hi Angelo,

"+ At the end of each file, the sending program shall send EOT up to ten
times until it receives an ACK character. (This is part of the XMODEM spec.)"

Why is u-boot not allowed to send an ACK ? I do not see this behavior on the protocol. Apart of that, which wrong behavior do you see on your target ? Can you transfer a file to your board ?

I have tested, no issue found:

loady
## Ready for binary (ymodem) download to 0x90800000 at 115200 bps...

C## Total Size = 0x0003c418 = 246808 Bytes

Best regards,
Stefano Babic

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Hello Stefano,

i apologize, you posted a detail i lost reading the spec. I can successfully transfert a file to my board, no problem on this.

Anyway, i am implementing a "sender" side sw, i am quite sure i am losing some other details, but if you want to check, i noticed these possible issues:

1.
(SPEC)
Modification Date The mod date is optional, and the filename and length may be sent without requiring the mod date to be sent.
Iff the modification date is sent, a single space separates the modification date from the file length.

You seems always be looking for the space, but if the file size only is sent (rest of the block must be set to NUL), seems you cannot read the value.

2.
Could you use the file size to ACK and close the transfert immediately after all the file has been received, so that 2 subsequent EOT from the sender are not requested ?

3.
Anyway, looking this sequence for a single Y_Modem file transmission,+ i don't understand why u-boot never sends the "NAK" on first EOT, but sends an ACK.

              SENDER                                  RECEIVER
                                                      "sb foo.*"
              "sending in batch mode etc."
                                                      C (command:rb)
              SOH 00 FF foo.c NUL[123] CRC CRC
                                                      ACK
                                                      C
              SOH 01 FE Data[128] CRC CRC
                                                      ACK
              SOH 02 FC Data[128] CRC CRC
                                                      ACK
              SOH 03 FB Data[100] CPMEOF[28] CRC CRC
                                                      ACK
              EOT
                                                      NAK <------
              EOT
                                                      ACK
                                                      C
              SOH 00 FF NUL[128] CRC CRC
                                                      ACK