does tm4c1294 support tcp or udp packet checksum hardware calculation?

Ruoshi Zhang

Hello,

i know that tm4c1294 itself can calculate checksum for icmp packets, for example, in enet_uip example, uip.c, i get these lines of code,

#if UIP_OFFLOAD_ICMP_CHKSUM
  /* If the hardware is inserting ICMP checksums for us, clear the field to
     ensure that the correct checksum is calculated. */
  ICMPBUF->icmpchksum = 0;

which means the hardware will take care of checksum by put UIP_OFFLOAD_ICMP_CHKSUM into preprocessor.

so does the chip support checksum calculation for udp/tcp packet? if it does, what should i put in preprocessor field and does any document provide this information?

over 10 years ago

0 Amit Ashara over 10 years ago

TI__Guru**** 244400 points

Hello Ruoshi,

Please refer to the Datasheet Chapter for Ethernet specifically the Table titled "Enhanced Transmit Descriptor 0 (TDES0)" for more description on CIC field

Regards

Amit

0 Ruoshi Zhang over 10 years ago in reply to Amit Ashara

Prodigy 160 points

Hi Amit,

thank you for point me out this information, then i got this question, if this is already set in the descriptor, then why do they do what i copied in my question? it seems unnecessary.

0 Amit Ashara over 10 years ago in reply to Ruoshi Zhang

TI__Guru**** 244400 points

Hello Ruoshi,

The location for the checksum will be a psuedo-checksum value of 0 if the CIC is 0x3, which will be replaced by the MAC Controller.

Regards

Amit

0 Shawn Gardner over 10 years ago in reply to Amit Ashara

Intellectual 260 points

Hi Amit,

Since the hardware calculates the checksum, then in the TivaWare example "enet_uip" example, shouldn't:

Properties->ARM Compiler->Advanced Options->Predefined Symbols->UIP_OFFLOAD_ICMP_CHKSUM

change to

UIP_OFFLOAD_ICMP_CHKSUM=1

because of the

#if UIP_OFFLOAD_ICMP_CHKSUM

in uip.c is not a #ifdef?

Either will work, but I believe the intention of the example is to avoid having software do the calculation unnecessarily.

Thanks.

0 Amit Ashara over 10 years ago in reply to Shawn Gardner

TI__Guru**** 244400 points

Hello Shawn

There are two files which use the UIP_OFFLOAD_ICMP_CHKSUM. One is uip.c and other is uip-fw.c which uses it with a #ifdef

Regards
Amit

0 Shawn Gardner over 10 years ago in reply to Amit Ashara

Intellectual 260 points

Hello Amit,

Yes, so that means for the example "enet_uip" the checksum in uip.c will be calculated unnecessarily because of the #if UIP_OFFLOAD_ICMP_CHKSUM (not #ifdef). So my recommendation for this example is to change the project Properties in Predefined Symbols from UIP_OFFLOAD_ICMP_CHKSUM to UIP_OFFLOAD_ICMP_CHKSUM=1. This will satisfy the #if and #ifndef in both files.

Regards,

Shawn

0 Amit Ashara over 10 years ago in reply to Shawn Gardner

TI__Guru**** 244400 points

Hello Shawn

Yes, you are right. That would do the job.

Regards
Amit

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does tm4c1294 support tcp or udp packet checksum hardware calculation?