#67 LTP segment retransmission rate instrumentation

[Leigh Torgerson]

For several radio projects we are working, it is desired to infer the quality of the link so that automatic changes in various radio parameters may be made by the radio software. It is desired to be able to monitor the LTP segment retransmission rate and thereby use that to infer the average link quality. (Could be a counter that is accessible to another utility that is reset by the reading app when it reads the counter, and that sets an overflow flag if the count gets too high before being reset.)

[Scott Burleigh]

Good idea, and should be doable for 3.6.2.

[Scott Burleigh]

Implemented this feature by adding new per-span fields (outputSegReXmitCount and outputSegReXmitBytes) to the NmltpSpan structure and populating them when data segments are retransmitted over the corresponding span. Any utility program that links with the nm library can obtain those values by calling ltpnm_span_get and looking into the NmltpSpan structure that the function returns. The standard ltpnm_span_reset function resets these fields along with all other nm fields.