SM6FBQ / HackRF clone - History

Clarify variables used in TX callback.

The power measurement depends on the number of bytes that were valid
from the previous use of the transfer buffer.

The number of bytes to be read to fill the next transfer, is the full
size of the buffer.

Detect hardware platform at run-time.

Firmware now detects the hardware it is running on at startup and
refuses to run if it is compiled for the wrong platform. The board ID
returned by firmware to the host is now derived from run-time detection
rather than a compile-time value. A separate method to retrieve
compile-time supported platform is added.

On HackRF One, pin straps are checked to determine hardware revision.
This is informational to aid troubleshooting and does not affect any
function.

Merge pull request #1139 from martinling/tx-flush

Support flushing the device TX buffer before ending transmission

firmware: use consistent clock source

CLKOUT now switches to the active clock source whenever the internal
clocks change source. It previously did so only when (re)enabled.

Merge pull request #1153 from greatscottgadgets/measure-power

Measure digital signal power, not amplitude in hackrf_transfer

hackrf_transfer: report on only actual transfers

The statistics reported to the user now reflect only completed USB
transfers and do not include information about the empty buffers that
are preloaded with data at the start of a TX operation.

libhackrf: add transfer buffer size access calls

Applications may need to learn the size of the USB transfer buffer
queue, for example to determine how many bytes will be preloaded with
calls to the TX callback.