1 files changed, 114 insertions, 0 deletions
diff --git a/src/pico/adafruit_register/i2c_bits.py b/src/pico/adafruit_register/i2c_bits.py
new file mode 100755
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+++ b/src/pico/adafruit_register/i2c_bits.py
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+# SPDX-FileCopyrightText: 2016 Scott Shawcroft for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+# pylint: disable=too-few-public-methods
+
+"""
+`adafruit_register.i2c_bits`
+====================================================
+
+Multi bit registers
+
+* Author(s): Scott Shawcroft
+"""
+
+__version__ = "0.0.0+auto.0"
+__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_Register.git"
+
+try:
+    from typing import Optional, Type, NoReturn
+    from circuitpython_typing.device_drivers import I2CDeviceDriver
+except ImportError:
+    pass
+
+
+class RWBits:
+    """
+    Multibit register (less than a full byte) that is readable and writeable.
+    This must be within a byte register.
+
+    Values are `int` between 0 and 2 ** ``num_bits`` - 1.
+
+    :param int num_bits: The number of bits in the field.
+    :param int register_address: The register address to read the bit from
+    :param int lowest_bit: The lowest bits index within the byte at ``register_address``
+    :param int register_width: The number of bytes in the register. Defaults to 1.
+    :param bool lsb_first: Is the first byte we read from I2C the LSB? Defaults to true
+    :param bool signed: If True, the value is a "two's complement" signed value.
+                        If False, it is unsigned.
+    """
+
+    def __init__(  # pylint: disable=too-many-arguments
+        self,
+        num_bits: int,
+        register_address: int,
+        lowest_bit: int,
+        register_width: int = 1,
+        lsb_first: bool = True,
+        signed: bool = False,
+    ) -> None:
+        self.bit_mask = ((1 << num_bits) - 1) << lowest_bit
+        # print("bitmask: ",hex(self.bit_mask))
+        if self.bit_mask >= 1 << (register_width * 8):
+            raise ValueError("Cannot have more bits than register size")
+        self.lowest_bit = lowest_bit
+        self.buffer = bytearray(1 + register_width)
+        self.buffer[0] = register_address
+        self.lsb_first = lsb_first
+        self.sign_bit = (1 << (num_bits - 1)) if signed else 0
+
+    def __get__(
+        self,
+        obj: Optional[I2CDeviceDriver],
+        objtype: Optional[Type[I2CDeviceDriver]] = None,
+    ) -> int:
+        with obj.i2c_device as i2c:
+            i2c.write_then_readinto(self.buffer, self.buffer, out_end=1, in_start=1)
+        # read the number of bytes into a single variable
+        reg = 0
+        order = range(len(self.buffer) - 1, 0, -1)
+        if not self.lsb_first:
+            order = reversed(order)
+        for i in order:
+            reg = (reg << 8) | self.buffer[i]
+        reg = (reg & self.bit_mask) >> self.lowest_bit
+        # If the value is signed and negative, convert it
+        if reg & self.sign_bit:
+            reg -= 2 * self.sign_bit
+        return reg
+
+    def __set__(self, obj: I2CDeviceDriver, value: int) -> None:
+        value <<= self.lowest_bit  # shift the value over to the right spot
+        with obj.i2c_device as i2c:
+            i2c.write_then_readinto(self.buffer, self.buffer, out_end=1, in_start=1)
+            reg = 0
+            order = range(len(self.buffer) - 1, 0, -1)
+            if not self.lsb_first:
+                order = range(1, len(self.buffer))
+            for i in order:
+                reg = (reg << 8) | self.buffer[i]
+            # print("old reg: ", hex(reg))
+            reg &= ~self.bit_mask  # mask off the bits we're about to change
+            reg |= value  # then or in our new value
+            # print("new reg: ", hex(reg))
+            for i in reversed(order):
+                self.buffer[i] = reg & 0xFF
+                reg >>= 8
+            i2c.write(self.buffer)
+
+
+class ROBits(RWBits):
+    """
+    Multibit register (less than a full byte) that is read-only. This must be
+    within a byte register.
+
+    Values are `int` between 0 and 2 ** ``num_bits`` - 1.
+
+    :param int num_bits: The number of bits in the field.
+    :param int register_address: The register address to read the bit from
+    :param type lowest_bit: The lowest bits index within the byte at ``register_address``
+    :param int register_width: The number of bytes in the register. Defaults to 1.
+    """
+
+    def __set__(self, obj: I2CDeviceDriver, value: int) -> NoReturn:
+        raise AttributeError()