/usr/share/pyshared/pymodbus/payload.py is in python-pymodbus 0.9.0+r175-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Modbus Payload Builders
------------------------
A collection of utilities for building and decoding
modbus messages payloads.
'''
from struct import pack, unpack
from pymodbus.constants import Endian
class PayloadBuilder(object):
'''
A utility that helps build payload messages to be
written with the various modbus messages. It really is just
a simple wrapper around the struct module, however it saves
time looking up the format strings. What follows is a simple
example::
builder = PayloadBuilder(endian=Endian.Little)
builder.add_8bit_uint(1)
builder.add_16bit_uint(2)
payload = builder.tostring()
'''
def __init__(self, payload=None, endian=Endian.Little):
''' Initialize a new instance of the payload builder
:param payload: Raw payload data to initialize with
:param endian: The endianess of the payload
'''
self._payload = payload or []
self._endian = endian
def reset(self):
''' Reset the payload buffer
'''
self._payload = []
def tostring(self):
''' Return the payload buffer as a string
:returns: The payload buffer as a string
'''
return ''.join(self._payload)
def tolist(self):
''' Return the payload buffer as a list
:returns: The payload buffer as a list
'''
return self._payload
def add_8bit_uint(self, value):
''' Adds a 8 bit unsigned int to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'B'
self._payload.append(pack(fstring, value))
def add_16bit_uint(self, value):
''' Adds a 16 bit unsigned int to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'H'
self._payload.append(pack(fstring, value))
def add_32bit_uint(self, value):
''' Adds a 32 bit unsigned int to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'I'
self._payload.append(pack(fstring, value))
def add_64bit_uint(self, value):
''' Adds a 64 bit unsigned int to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'Q'
self._payload.append(pack(fstring, value))
def add_8bit_int(self, value):
''' Adds a 8 bit signed int to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'b'
self._payload.append(pack(fstring, value))
def add_16bit_int(self, value):
''' Adds a 16 bit signed int to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'h'
self._payload.append(pack(fstring, value))
def add_32bit_int(self, value):
''' Adds a 32 bit signed int to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'i'
self._payload.append(pack(fstring, value))
def add_64bit_int(self, value):
''' Adds a 64 bit signed int to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'q'
self._payload.append(pack(fstring, value))
def add_32bit_float(self, value):
''' Adds a 32 bit float to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'f'
self._payload.append(pack(fstring, value))
def add_64bit_float(self, value):
''' Adds a 64 bit float(double) to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 'd'
self._payload.append(pack(fstring, value))
def add_string(self, value):
''' Adds a string to the buffer
:param value: The value to add to the buffer
'''
fstring = self._endian + 's'
for c in value:
self._payload.append(pack(fstring, c))
class PayloadDecoder(object):
'''
A utility that helps decode payload messages from a modbus
reponse message. It really is just a simple wrapper around
the struct module, however it saves time looking up the format
strings. What follows is a simple example::
decoder = PayloadDecoder(self.little_endian_payload)
first = decoder.decode_8bit_uint()
second = decoder.decode_16bit_uint()
'''
def __init__(self, payload, endian=Endian.Little):
''' Initialize a new payload decoder
:param payload: The payload to decode with
:param endian: The endianess of the payload
'''
self._payload = payload
self._pointer = 0x00
self._endian = endian
def reset(self):
''' Reset the decoder pointer back to the start
'''
self._pointer = 0x00
def decode_8bit_uint(self):
''' Decodes a 8 bit unsigned int from the buffer
'''
self._pointer += 1
fstring = self._endian + 'B'
handle = self._payload[self._pointer - 1:self._pointer]
return unpack('B', handle)[0]
def decode_16bit_uint(self):
''' Decodes a 16 bit unsigned int from the buffer
'''
self._pointer += 2
fstring = self._endian + 'H'
handle = self._payload[self._pointer - 2:self._pointer]
return unpack(fstring, handle)[0]
def decode_32bit_uint(self):
''' Decodes a 32 bit unsigned int from the buffer
'''
self._pointer += 4
fstring = self._endian + 'I'
handle = self._payload[self._pointer - 4:self._pointer]
return unpack(fstring, handle)[0]
def decode_64bit_uint(self):
''' Decodes a 64 bit unsigned int from the buffer
'''
self._pointer += 8
fstring = self._endian + 'Q'
handle = self._payload[self._pointer - 8:self._pointer]
return unpack(fstring, handle)[0]
def decode_8bit_int(self):
''' Decodes a 8 bit signed int from the buffer
'''
self._pointer += 1
fstring = self._endian + 'b'
handle = self._payload[self._pointer - 1:self._pointer]
return unpack(fstring, handle)[0]
def decode_16bit_int(self):
''' Decodes a 16 bit signed int from the buffer
'''
self._pointer += 2
fstring = self._endian + 'h'
handle = self._payload[self._pointer - 2:self._pointer]
return unpack(fstring, handle)[0]
def decode_32bit_int(self):
''' Decodes a 32 bit signed int from the buffer
'''
self._pointer += 4
fstring = self._endian + 'i'
handle = self._payload[self._pointer - 4:self._pointer]
return unpack(fstring, handle)[0]
def decode_64bit_int(self):
''' Decodes a 64 bit signed int from the buffer
'''
self._pointer += 8
fstring = self._endian + 'q'
handle = self._payload[self._pointer - 8:self._pointer]
return unpack(fstring, handle)[0]
def decode_32bit_float(self):
''' Decodes a 32 bit float from the buffer
'''
self._pointer += 4
fstring = self._endian + 'f'
handle = self._payload[self._pointer - 4:self._pointer]
return unpack(fstring, handle)[0]
def decode_64bit_float(self):
''' Decodes a 64 bit float(double) from the buffer
'''
self._pointer += 8
fstring = self._endian + 'd'
handle = self._payload[self._pointer - 8:self._pointer]
return unpack(fstring, handle)[0]
def decode_string(self, size=1):
''' Decodes a string from the buffer
:param size: The size of the string to decode
'''
self._pointer += size
return self._payload[self._pointer - size:self._pointer]
#---------------------------------------------------------------------------#
# Exported Identifiers
#---------------------------------------------------------------------------#
__all__ = ["PayloadBuilder", "PayloadDecoder"]
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