3 files changed, 291 insertions, 17 deletions

diff --git a/README b/README
index 7213aa6..652f5cf 100644
--- a/README
+++ b/README
@@ -32,28 +32,37 @@ $ . glucometerutils-venv/bin/activate
 Please see the following table for the driver for each device that is known and
 supported.
 
-| Manufacturer | Model Name                 | Driver             | Dependencies              |
-| ---          | ---                        | ---                | ---                       |
-| LifeScan     | OneTouch Ultra 2           | `otultra2`         | [pyserial]                |
-| LifeScan     | OneTouch Ultra Easy        | `otultraeasy`      | [construct] [pyserial]    |
-| LifeScan     | OneTouch Ultra Mini        | `otultraeasy`      | [construct] [pyserial]    |
-| LifeScan     | OneTouch Verio IQ          | `otverioiq`        | [construct] [pyserial]    |
-| LifeScan     | OneTouch Verio (USB)       | `otverio2015`      | [construct] [python-scsi] |
-| LifeScan     | OneTouch Select Plus       | `otverio2015`      | [construct] [python-scsi] |
-| LifeScan     | OneTouch Select Plus Flex¹ | `otverio2015`      | [construct] [python-scsi] |
-| Abbott       | FreeStyle InsuLinx†        | `fsinsulinx`       | [construct] [hidapi]‡     |
-| Abbott       | FreeStyle Libre            | `fslibre`          | [construct] [hidapi]‡     |
-| Abbott       | FreeStyle Optium           | `fsoptium`         | [pyserial]                |
-| Abbott       | FreeStyle Precision Neo    | `fsprecisionneo`   | [construct] [hidapi]‡     |
-| Abbott       | FreeStyle Optium Neo       | `fsprecisionneo`   | [construct] [hidapi]‡     |
-| Abbott       | FreeStyle Optium Neo H     | `fsprecisionneo`   | [construct] [hidapi]‡     |
-| Roche        | Accu-Chek Mobile           | `accuchek_reports` |                           |
-| SD Biosensor | SD CodeFree                | `sdcodefree`       | [construct] [pyserial]    |
+| Manufacturer | Model Name                 | Driver             | Dependencies                      |
+| ---          | ---                        | ---                | ---                               |
+| LifeScan     | OneTouch Ultra 2           | `otultra2`         | [pyserial]                        |
+| LifeScan     | OneTouch Ultra Easy        | `otultraeasy`      | [construct] [pyserial]            |
+| LifeScan     | OneTouch Ultra Mini        | `otultraeasy`      | [construct] [pyserial]            |
+| LifeScan     | OneTouch Verio IQ          | `otverioiq`        | [construct] [pyserial]            |
+| LifeScan     | OneTouch Verio (USB)       | `otverio2015`      | [construct] [python-scsi]         |
+| LifeScan     | OneTouch Select Plus       | `otverio2015`      | [construct] [python-scsi]         |
+| LifeScan     | OneTouch Select Plus Flex¹ | `otverio2015`      | [construct] [python-scsi]         |
+| Abbott       | FreeStyle InsuLinx†        | `fsinsulinx`       | [construct] [hidapi]‡             |
+| Abbott       | FreeStyle Libre            | `fslibre`          | [construct] [hidapi]‡             |
+| Abbott       | FreeStyle Optium           | `fsoptium`         | [pyserial]                        |
+| Abbott       | FreeStyle Precision Neo    | `fsprecisionneo`   | [construct] [hidapi]‡             |
+| Abbott       | FreeStyle Optium Neo       | `fsprecisionneo`   | [construct] [hidapi]‡             |
+| Abbott       | FreeStyle Optium Neo H     | `fsprecisionneo`   | [construct] [hidapi]‡             |
+| Roche        | Accu-Chek Mobile           | `accuchek_reports` |                                   |
+| SD Biosensor | SD CodeFree                | `sdcodefree`       | [construct] [pyserial]            |
+| TaiDoc       | TD-4277                    | `td4277`           | [construct] [pyserial]² [hidapi]  |
+| GlucoRx      | Nexus                      | `td4277`           | [construct] [pyserial]² [hidapi]  |
+| Menarini     | GlucoMen Nexus             | `td4277`           | [construct] [pyserial]² [hidapi]  |
+| Aktivmed     | GlucoCheck XL              | `td4277`           | [construct] [pyserial]² [hidapi]  |
 
 † Untested.
+
 ‡ Optional dependency on Linux; required on other operating systems.
+
 ¹ USB only, bluetooth not supported.
 
+² Requires a version of pyserial supporting CP2110 bridges. See [this pyserial
+pull request](https://github.com/pyserial/pyserial/pull/411).
+
 To identify the supported features for each of the driver, query the `help`
 action:
 
diff --git a/glucometerutils/drivers/td4277.py b/glucometerutils/drivers/td4277.py
new file mode 100644
index 0000000..3a5051b
--- /dev/null
+++ b/glucometerutils/drivers/td4277.py
@@ -0,0 +1,234 @@
+# -*- coding: utf-8 -*-
+#
+# SPDX-License-Identifier: MIT
+"""Driver for TaiDoc TD-4277 devices.
+
+Supported features:
+    - get readings, including pre-/post-meal notes;
+    - get and set date and time;
+    - get serial number (partial);
+    - memory reset (caution!)
+
+Expected device path: 0001:001c:00 (libusb), /dev/hidraw1 (Linux).
+"""
+
+import binascii
+import datetime
+import enum
+import functools
+import logging
+import operator
+
+import construct
+
+from glucometerutils import common
+from glucometerutils import exceptions
+from glucometerutils.support import serial
+
+class Direction(enum.Enum):
+    In = 0xa5
+    Out = 0xa3
+
+
+def byte_checksum(data):
+    return functools.reduce(operator.add, data) & 0xFF
+
+
+_PACKET = construct.Struct(
+    'data' / construct.RawCopy(
+        construct.Struct(
+            construct.Const(b'\x51'),
+            'command' / construct.Byte,
+            'message' / construct.Bytes(4),
+            'direction' / construct.Mapping(
+                construct.Byte,
+                {e: e.value for e in Direction}),
+        ),
+    ),
+    'checksum' / construct.Checksum(
+        construct.Byte, byte_checksum, construct.this.data.data),
+)
+
+_EMPTY_MESSAGE = 0
+
+_CONNECT_REQUEST = 0x22
+_VALID_CONNECT_RESPONSE = {0x22, 0x24, 0x54}
+
+_GET_DATETIME = 0x23
+_SET_DATETIME = 0x33
+
+_GET_MODEL = 0x24
+
+_GET_READING_COUNT = 0x2b
+_GET_READING_DATETIME = 0x25
+_GET_READING_VALUE = 0x26
+
+_CLEAR_MEMORY = 0x52
+
+_MODEL_STRUCT = construct.Struct(
+    construct.Const(b'\x77\x42'),
+    construct.Byte,
+    construct.Byte,
+)
+
+_DATETIME_STRUCT = construct.Struct(
+    'day' / construct.Int16ul,
+    'minute' / construct.Byte,
+    'hour' / construct.Byte,
+)
+
+_DAY_BITSTRUCT = construct.BitStruct(
+    'year' / construct.BitsInteger(7),
+    'month' / construct.BitsInteger(4),
+    'day' / construct.BitsInteger(5),
+)
+
+_READING_COUNT_STRUCT = construct.Struct(
+    'count' / construct.Int16ul,
+    construct.Int16ul,
+)
+
+_READING_SELECTION_STRUCT = construct.Struct(
+    'record_id' / construct.Int16ul,
+    construct.Const(b'\x00\x00'),
+)
+
+_MEAL_FLAG = {
+    common.Meal.NONE: 0x00,
+    common.Meal.BEFORE: 0x40,
+    common.Meal.AFTER: 0x80,
+}
+
+_READING_VALUE_STRUCT = construct.Struct(
+    'value' / construct.Int16ul,
+    construct.Const(b'\x06'),
+    'meal'/ construct.Mapping(
+        construct.Byte, _MEAL_FLAG),
+)
+
+def _make_packet(command, message, direction=Direction.Out):
+    return _PACKET.build(
+        {'data': {
+            'value': {
+                'command': command,
+                'message': message,
+                'direction': direction,
+            },
+        }})
+
+
+def _parse_datetime(message):
+    date = _DATETIME_STRUCT.parse(message)
+    # We can't parse the day properly with a single pass of Construct
+    # unfortunately.
+    day = _DAY_BITSTRUCT.parse(construct.Int16ub.build(date.day))
+    return datetime.datetime(
+        2000+day.year, day.month, day.day, date.hour, date.minute)
+
+
+def _select_record(record_id):
+    return _READING_SELECTION_STRUCT.build({'record_id': record_id})
+
+
+class Device(serial.SerialDevice):
+    BAUDRATE = 19200
+    TIMEOUT = 0.5
+
+    def __init__(self, device):
+        super(Device, self).__init__('cp2110://' + device)
+        self.buffered_reader_ = construct.Rebuffered(
+            _PACKET, tailcutoff=1024)
+
+    def _send_command(
+            self, command, message=_EMPTY_MESSAGE, validate_response=True):
+        pkt = _make_packet(command, message)
+        logging.debug('sending packet: %s', binascii.hexlify(pkt))
+
+        self.serial_.write(pkt)
+        self.serial_.flush()
+        response = self.buffered_reader_.parse_stream(self.serial_)
+        logging.debug('received packet: %r', response)
+
+        if validate_response and response.data.value.command != command:
+            raise InvalidResponse(response)
+
+        return response.data.value.command, response.data.value.message
+
+    def connect(self):
+        response_command, message = self._send_command(
+            _CONNECT_REQUEST, validate_response=False)
+        if response_command not in _VALID_CONNECT_RESPONSE:
+            raise exceptions.ConnectionFailed(
+                'Invalid response received: %2x %r' % (
+                    response_command, message))
+
+        _, model_message = self._send_command(_GET_MODEL)
+        try:
+            _MODEL_STRUCT.parse(model_message)
+        except construct.ConstructError:
+            raise exceptions.ConnectionFailed(
+                'Invalid model identified: %r' % model_message)
+
+    def disconnect(self):
+        pass
+
+    def get_meter_info(self):
+        return common.MeterInfo('TaiDoc TD-4277 glucometer')
+
+    def get_version(self):  # pylint: disable=no-self-use
+        raise NotImplementedError
+
+    def get_serial_number(self):  # pylint: disable=no-self-use
+        raise NotImplementedError
+
+    def get_datetime(self):
+        _, message = self._send_command(_GET_DATETIME)
+
+        return _parse_datetime(message)
+
+    def set_datetime(self, date=datetime.datetime.now()):
+        assert date.year >= 2000
+
+        day_struct = _DAY_BITSTRUCT.build({
+            'year': date.year - 2000,
+            'month': date.month,
+            'day': date.day,
+        })
+
+        day_word = construct.Int16ub.parse(day_struct)
+
+        date_message = _DATETIME_STRUCT.build({
+            'day': day_word,
+            'minute': date.minute,
+            'hour': date.hour})
+
+        _, message = self._send_command(_SET_DATETIME, message=date_message)
+
+        return _parse_datetime(message)
+
+    def _get_reading_count(self):
+        _, message = self._send_command(_GET_READING_COUNT)
+
+        return _READING_COUNT_STRUCT.parse(message).count
+
+    def _get_reading(self, record_id):
+        _, reading_date_message = self._send_command(
+            _GET_READING_DATETIME,
+            _select_record(record_id))
+        reading_date = _parse_datetime(reading_date_message)
+
+        _, reading_value_message = self._send_command(
+            _GET_READING_VALUE,
+            _select_record(record_id))
+        reading_value = _READING_VALUE_STRUCT.parse(reading_value_message)
+
+        return common.GlucoseReading(
+            reading_date, reading_value.value, meal=reading_value.meal)
+
+    def get_readings(self):
+        record_count = self._get_reading_count()
+        for record_id in range(record_count):
+            yield self._get_reading(record_id)
+
+    def zero_log(self):
+        self._send_command(_CLEAR_MEMORY)
diff --git a/test/test_td4277.py b/test/test_td4277.py
new file mode 100644
index 0000000..6f4ff9a
--- /dev/null
+++ b/test/test_td4277.py
@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+#
+# SPDX-License-Identifier: MIT
+"""Tests for the TD-4277 driver."""
+
+# pylint: disable=protected-access,missing-docstring
+
+import datetime
+
+from absl.testing import parameterized
+
+from glucometerutils.drivers import td4277
+from glucometerutils.support import lifescan
+from glucometerutils import exceptions
+
+
+class TestTD4277Nexus(parameterized.TestCase):
+
+    @parameterized.parameters(
+        (b'\x21\x24\x0e\x15', datetime.datetime(2018, 1, 1, 21, 14)),
+        (b'\x21\x26\x0e\x15', datetime.datetime(2019, 1, 1, 21, 14)),
+        (b'\x04\x27\x25\x0d', datetime.datetime(2019, 8, 4, 13, 37)),
+    )
+    def test_parse_datetime(self, message, date):
+        self.assertEqual(td4277._parse_datetime(message),
+                         date)
+
+    def test_making_message(self):
+        self.assertEqual(
+            td4277._make_packet(0x22, 0),
+            b'\x51\x22\x00\x00\x00\x00\xa3\x16')