def do_send_recvs(self):
meter_packet = np.zeros(METERING_PACKET_SIZE, dtype=np.float64)
first_meter_index_needed = 0
while True:
dirty = self._param_mem_dirty.nonzero()[0]
meter_words_desired = METERING_PACKET_SIZE - first_meter_index_needed
if len(dirty) == 0:
if meter_words_desired <= 0:
# All sending and receiving this time is complete.
break
# Otherwise, pick a random address to start from
first_param_send_index = random.randrange(max(0, len(self._param_mem_contents) - self.spi_words))
else:
first_param_send_index = dirty[0]
param_data_to_send = self._param_mem_contents[first_param_send_index:]
if len(param_data_to_send) > self.spi_words:
param_data_to_send = param_data_to_send[: self.spi_words]
words_in_transfer = len(param_data_to_send)
read_buf = self._read_buf[:words_in_transfer]
# Unpack floats into fixed point in the write buffer.
write_buf = self._write_buf[:words_in_transfer]
wireformat.floats_to_fixeds(param_data_to_send, PARAM_INT_BITS, PARAM_FRAC_BITS, write_buf.view(np.int64))
# print '{} @ rd: {} wr: {}'.format(words_in_transfer, first_meter_index_needed, first_param_send_index)
self.spi_channel.transfer(
read_addr=first_meter_index_needed,
read_data=read_buf,
write_addr=first_param_send_index,
write_data=write_buf,
)
# Mark param memory segment not dirty.
self._param_mem_dirty[first_param_send_index : first_param_send_index + words_in_transfer] = 0
# Extract the metering data we got.
meter_vals_read = read_buf[:meter_words_desired]
wireformat.sign_extend(meter_vals_read, METER_SIGN_BIT)
wireformat.fixeds_to_floats(
meter_vals_read.view(np.int64),
METER_FRAC_BITS,
meter_packet[first_meter_index_needed : first_meter_index_needed + len(meter_vals_read)],
)
# TODO: wraparound, since the meter data at the beginning of the packet is going to be newer.
first_meter_index_needed += words_in_transfer
break # FIXME.
self._meter_revision += 1
np.maximum(2 ** -METER_FRAC_BITS, meter_packet, out=meter_packet)
# meter packet contains LPF of square of signal value right-shifted by 2 bits.
# So: correct for the shift, correct for the crest factor, sqrt, and convert to dB.
meter_values = 20 * np.log10(np.sqrt(meter_packet * 2 ** 2 * 2))
self._meter_mem_contents = (self._meter_revision, meter_values)
def test_fixed_to_float():
ref = np.array([2**-30, -(2**-30), 1, -1, 2**5 - 2**-30, -2**5 ])
fixeds = np.array([ 1, -1, 2**30, -2**30, 2**35 - 1, -2**35], dtype=np.int64)
out = np.empty(len(fixeds), dtype=np.float64)
wireformat.fixeds_to_floats(fixeds, 30, out)
assert np.all(out == ref)
