Avnet normally delivers their own reference design as they are providing technical supports for their kits.
As far as 4DSP reference design is concerned, there is a loop back reference design available. It is meant to loop back DAC data onto the ADC and save the actual buffers to the hard disk.
Chapter 11 of the 4FM Getting Started Guide covers the steps on how to run the application.
The paths to the actual reference design items is found at:
The firmware is under : C:\Program Files (x86)\4dsp\Common\Firmware\Recovery\266_zc702_fmc150 (Bit files)
The firmware is under : C:\Program Files (x86)\4dsp\Common\Firmware\Extracted\266_zc702_fmc150 (Sources)
The software is under : C:\Program Files (x86)\4dsp\FMC Board Support Package\Refs\Software\FMC15x (Source codes)
The software is under : C:\Program Files (x86)\4dsp\FMC Board Support Package\Bins (Compiled)
The documentation of the firmware and software is to be found in the firmware and software sources package.
I hope that helps,
Arnaud