Feeding hardware-decoded packets into libsigrok

Soeren Apel came up with an interesting use-case:

The yokogawa DLM2000 series can do I2C decoding on the device, and feed the I2C packets and associated metadata to an SCPI client:

:SERialbus<x>:I2C:DETail:LIST:ITEM?
Queries all items that will be displayed in the I2C
bus signal analysis result list.
 
Example :SERIALBUS1:I2C:DETAIL:LIST:ITEM?
-> "No.,Time(ms),1st,2nd,R/W,Data,Information"
 
 
:SERialbus<x>:I2C:DETail:LIST:VALue?
Queries all of the data for the specified analysis
number in the I2C bus signal analysis result list.
 
Example :SERIALBUS1:I2C:DETAIL:LIST:VALUE? 0
-> "0,-0.07000,AA*,,W,AE*88*,7-bit"

This hardware-level decoder has access to more raw data than device ever feeds to sigrok: it cannot stream continually via SCPI transports, for example. So it's entirely possible, even likely, that the hardware can decode more I2C data from the raw signal than libsigrok/libsigrokdecode ever could.

Thus, this is a use-case for getting I2C packets from the hardware, associating it with libsigrok timing reference (sample numbers) and feeding to libsigrokdecode as an I2C packet -- to PDs that normally take their input from the libsigrokdecode I2C PD.

This involves:

• libsigrok would need a facility to send decoded packets over the session bus. This is certainly a new packet type, for example SR_DF_I2C.
• libsigrokdecode would need a way to receive more than just raw logic. The inter-PD Python object format for (in this case) I2C would need to be nailed down and formalized, and a way for the library to receive I2C in packet format and convert to the Python object.

Other scopes that can send decoded data over SCPI

Keysight InfiniiVision 3000 X-Series Oscilloscopes and Agilent InfiniiVision 7000A Series Oscilloscopes:

:LISTer:DATA
Query Syntax :LISTer:DATA?
The :LISTer:DATA? query returns the lister data.
Return Format <binary block><NL>
<binary_block> ::= comma-separated data with newlines at the end of each row

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