zcbor map of empty string not returning what i expect.

RE: zcbor map of empty string not returning what i expect.

Menon — Thu, 13 Feb 2025 10:07:28 GMT

Hello,

While checking the ZCbor library, indefinite length encoding is triggered inside zcbor_map_start_encode(), which calls list_map_start_encode(), where the encoding behavior depends on the max_num parameter. So, I guess if max_num is not set to 0, the function inserts BF and FF. Can you try zcbor_map_start_encode(encoding_state, 0); and see if this resolves the issue? See value encode()

Kind Regards,

Abhijith

RE: zcbor map of empty string not returning what i expect.

Spector — Thu, 13 Feb 2025 07:20:44 GMT

This particular forum thread has been raised regarding the zcbor code provided by nordic semi. It has nothing to do with the smp_hdr part. The smp_hdr data length is 2 in my instance because the zcbor map of nothing is represented by BF FF. RATHER than A0

However I've seen other tools generating A0.

This corresponds to ZCBOR_MAJOR_TYPE_MAP (5) existing on the top 3 bits and length 0 for the rest thus becoming 0xA0.

However in my code
r = r && zcbor_map_start_encode(encoding_state, 1);
r = r && zcbor_map_end_encode(encoding_state, 1);

Generates ZCBOR_MAJOR_TYPE_MAP (5) existing on the top 3 bits, with a length b'11111' thus becoming 0xBF.
When the length is indefinite it needs a break which is the 0xFF

I guess in the simplest terms what I'm asking is can i control the length field?

RE: zcbor map of empty string not returning what i expect.

Menon — Wed, 12 Feb 2025 15:19:57 GMT

Hello,

I am not sure about this, but the issue might be related to memory handling in the code. Could you verify whether sizeof(smp_msg.hdr) is correct and does not overrun smp_msg.data? Maybe try printing sizeof(smp_msg.hdr) and check if it matches the expected size.

Kind regards,
Abhijith

RE: zcbor map of empty string not returning what i expect.

Spector — Thu, 06 Feb 2025 08:15:30 GMT

Yes the stack allocated dealt with the b0, 06 issue. HOWEVER i still have BF FF where i was expecting A0

RE: zcbor map of empty string not returning what i expect.

Menon — Wed, 05 Feb 2025 15:50:51 GMT

Hello,

Did the switch to a fixed stack-allocated data field resolve the discrepancy in the FRAME contents?

Kind Regards,

Abhijith

RE: zcbor map of empty string not returning what i expect.

Spector — Wed, 05 Feb 2025 12:26:15 GMT

It's worth noting that payload [0] is BF and payload[1] is FF. The smp_msg.data was a pointer that meant i couldn't increment the pointer like i was doing...Maybe if i used a tripple ref, but I'm just gonna create a fixed stack allocated data field.