sql-edition/servers/VendingMachine.py

   1 # vim:ts=4
   2 import re
   3 from CRC import do_crc
   4 from select import select
   5
   6 asynchronous_responses = [      '400', '401', # door open/closed
   7                                 '610',        # switches changed
   8                                 '200', '201', '202', '203', '204', '205', '206',
   9                                 '207', '208', '209', '211', # key presses
  10                          ]
  11 DOOR = 1
  12 SWITCH = 2
  13 KEY = 3
  14
  15 class VendingException(Exception): pass
  16
  17 class VendingMachine:
  18         def __init__(self, rfh, wfh):
  19                 self.events = []
  20                 self.secret = 'AAAAAAAAAAAAAAAA'
  21                 self.rfh = rfh
  22                 self.wfh = wfh
  23                 self.challenge = None
  24                 # Initialise ourselves into a known state
  25                 self.wfh.write('\n')
  26                 self.await_prompt()
  27                 self.wfh.write('echo off\n')
  28                 self.await_prompt()
  29                 self.wfh.write('PING\n')
  30                 code = ''
  31                 while code != '000':
  32                         code = self.get_response()[0]
  33                 self.get_switches()
  34
  35         def await_prompt(self):
  36                 self.wfh.flush()
  37                 state = 1
  38                 prefix = ''
  39                 s = ''
  40                 while True:
  41                         try:
  42                                 s = self.rfh.read(1)
  43                         except socket.error:
  44                                 print "Blah, seems DEC server has fallen over"
  45                                 raise VendingException('failed to read input from vending machine')
  46                         if s == '': raise VendingException('nothing read!')
  47                         if s == '\n' or s == '\r':
  48                                 state = 1
  49                                 prefix = ''
  50                         if (s == '#' or s == '%') and state == 1: state = 2
  51                         if s == ' ' and state == 2:
  52                                 if prefix == '':
  53                                         self.challenge = None
  54                                         return
  55                                 if re.search('^[0-9a-fA-F]{4}$', prefix):
  56                                         self.challenge = int(prefix, 16)
  57                                         return
  58
  59         def get_response(self, async = False):
  60                 self.wfh.flush()
  61                 while True:
  62                         s = ''
  63                         while s == '':
  64                                 s = self.rfh.readline()
  65                                 if s == '': return None
  66                                 s = s.strip('\r\n')
  67                         code = s[0:3]
  68                         text = s[4:]
  69                         if code in asynchronous_responses:
  70                                 self.handle_event(code, text)
  71                                 if async: return None
  72                         else:
  73                                 self.await_prompt()
  74                                 return (code, text)
  75
  76         def get_switches(self):
  77                 self.wfh.write('S\n')
  78                 (code, text) = self.get_response()
  79                 if code != '600':
  80                         return (False, code, text)
  81                 self.interpret_switches(text)
  82                 return (True, code, text)
  83
  84         def interpret_switches(self, text):
  85                 self.switches = (int(text[0:2], 16) << 8) | int(text[3:5], 16)
  86
  87         def handle_event(self, code, text):
  88                 if code == '400':
  89                         self.events.append((DOOR, 0))
  90                 elif code == '401':
  91                         self.events.append((DOOR, 1))
  92                 elif code == '610':
  93                         self.events.append((SWITCH, None))
  94                         self.interpret_switches(text)
  95                 elif code[0] == '2':
  96                         self.events.append((KEY, int(code[1:3])))
  97                 else:
  98                         sys.stderr.write('WARNING: Unhandled event! (%s %s)\n'%(code,text))
  99
 100         def authed_message(self, message):
 101                 if self.challenge == None:
 102                         return message
 103                 crc = do_crc('%c%c'%(self.challenge >> 8, self.challenge & 0xff))
 104                 crc = do_crc(self.secret, crc)
 105                 crc = do_crc(message, crc)
 106                 return message+'|'+('%04x'%crc)
 107
 108         def ping(self):
 109                 self.wfh.write('PING\n')
 110                 (code, string) = self.get_response()
 111                 return (code == '000', code, string)
 112
 113         def vend(self, item):
 114                 if not re.search('^[0-9][0-9]$', item):
 115                         return (False, 'Invalid item requested (%s)'%item)
 116                 self.wfh.write(self.authed_message(('V%s\n'%item)+'\n'))
 117                 (code, string) = self.get_response()
 118                 return (code == '100', code, string)
 119
 120         def beep(self, duration = None, synchronous = True):
 121                 msg = 'B'
 122                 if synchronous: msg += 'S'
 123                 if duration != None:
 124                         if duration > 255: duration = 255
 125                         if duration < 1: duration = 1
 126                         msg += '%02x'%duration
 127                 self.wfh.write(msg+'\n')
 128                 (code, string) = self.get_response()
 129                 return (code == '500', code, string)
 130
 131         def silence(self, duration = None, synchronous = True):
 132                 msg = 'C'
 133                 if synchronous: msg += 'S'
 134                 if duration != None:
 135                         if duration > 255: duration = 255
 136                         if duration < 1: duration = 1
 137                         msg += '%02x'%duration
 138                 self.wfh.write(msg+'\n')
 139                 (code, string) = self.get_response()
 140                 return (code == '501', code, string)
 141
 142         def display(self, string):
 143                 if len(string) > 10:
 144                         string = string[0:10]
 145                 self.wfh.write('D'+string+'\n')
 146                 (code, string) = self.get_response()
 147                 return (code == '300', code, string)
 148
 149         def next_event(self, timeout = None):
 150                 # we don't want to buffer in the serial port, so we get all the events
 151                 # we can ASAP.
 152                 if len(self.events) > 0: timeout = 0
 153                 while True:
 154                         (r, _, _) = select([self.rfh], [], [], timeout)
 155                         if r:
 156                                 self.get_response(async = True)
 157                                 timeout = 0
 158                         else:
 159                                 break
 160                 if len(self.events) == 0: return None
 161                 ret = self.events[0]
 162                 del self.events[0]
 163                 return ret