# The MIT License (MIT)
#
# Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
#
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# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
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# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
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# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# 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"
[docs]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 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 __init__(self, num_bits, register_address, lowest_bit, register_width=1):
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
def __get__(self, obj, objtype=None):
with obj.i2c_device as i2c:
i2c.write_then_readinto(self.buffer, self.buffer,
out_end=1, in_start=1, stop=False)
# read the number of bytes into a single variable
reg = 0
for i in range(len(self.buffer)-1, 0, -1):
reg = (reg << 8) | self.buffer[i]
return (reg & self.bit_mask) >> self.lowest_bit
def __set__(self, obj, value):
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, stop=False)
reg = 0
for i in range(len(self.buffer)-1, 0, -1):
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 range(1, len(self.buffer)):
self.buffer[i] = reg & 0xFF
reg >>= 8
i2c.write(self.buffer)
[docs]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, value):
raise AttributeError()