def transfer(self, read_addr, read_data, write_addr, write_data):
buf_len_words = len(write_data)
if len(read_data) != buf_len_words:
raise ValueError("Read and write buffer sizes must match.")
buf_len_bytes = SPI_BYTES_PER_WORD * buf_len_words
address_offset_bytes = 2 * SPI_BYTES_PER_WORD
bytes_in_transfer = address_offset_bytes + buf_len_bytes
# Build the data packet: read addr, write addr, data.
write_buf = self.write_buf[:bytes_in_transfer]
read_buf = self.read_buf[:bytes_in_transfer]
self._addresses[0] = read_addr
self._addresses[1] = write_addr
fixeds_to_spi(self._addresses, write_buf[:address_offset_bytes])
fixeds_to_spi(write_data, write_buf[address_offset_bytes:])
# Do transfer.
self.dev.transfer(write_buf, read_buf)
# Unpack results
spi_to_fixeds(read_buf[address_offset_bytes:], read_data)
def test_spi_roundtrip(n=10, reps=100):
for i in xrange(reps):
# Encode ref, decode ref
fixeds = np.random.randint(2**36-1, size=n).astype(np.uint64)
ref_spi = fixeds_to_spi(fixeds)
ref_roundtrip_result = spi_to_fixeds(ref_spi)
assert np.all(fixeds==ref_roundtrip_result)
# Encode ref, decode cython
fixed_buf = np.empty(n, dtype=np.uint64)
wireformat.spi_to_fixeds(ref_spi, fixed_buf)
assert np.all(fixeds == fixed_buf)
# Encode cython, decode ref
spi_buf = np.empty(n * 8, dtype=np.uint8)
wireformat.fixeds_to_spi(ref_roundtrip_result, spi_buf)
assert np.all(spi_buf == ref_spi)
assert np.all(fixeds == spi_to_fixeds(spi_buf))
# Encode cython, decode cython
wireformat.fixeds_to_spi(fixeds, spi_buf)
wireformat.spi_to_fixeds(spi_buf, fixed_buf)
assert np.all(fixeds == fixed_buf)
