#!/usr/bin/python3

# Raspberry Pi LPC1114 I/O Processor Expansion Board SPI Agent Firmware
# transport service wrapper functions for Python3

# Copyright (C)2013-2018, Philip Munts, President, Munts AM Corp.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice,
#   this list of conditions and the following disclaimer.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

import ctypes
import platform
import struct

# Load the shared library

if platform.system().startswith('CYGWIN'):
  library_name = 'libspiagent.dll'
else:
  library_name = 'libspiagent.so'

libspiagent = ctypes.cdll.LoadLibrary(library_name)

# Open a connection to the specified server
#   servername is a string of the form:
#     [http://|ioctl://|oncrpc://|xmlrpc://]<host name>

def open(servername):
  perror = ctypes.c_int()
  libspiagent.spiagent_open(servername.encode(encoding='UTF-8'), ctypes.byref(perror))
  return perror.value

# Dispatch a command
#   cmd must be passed in as a list or tuple of 3 integers (command, pin, data)
#   resp must be passed in as an empty list and will be updated as
#   a list of 4 integers (command, pin, data, error)

def command(cmd, resp):
  pcmd = ctypes.c_char_p(struct.pack('iii', *cmd))
  presp = ctypes.create_string_buffer(16)
  perror = ctypes.c_int()
  libspiagent.spiagent_command(pcmd, presp, ctypes.byref(perror))
  resp += struct.unpack('iiii', presp)
  return perror.value

# Close the server connection

def close():
  perror = ctypes.c_int()
  libspiagent.spiagent_close(ctypes.byref(perror))
  return perror.value