+#!/usr/bin/env python
+
+import string
+
+class Idler:
+ def __init__(self, v):
+ self.v = v
+
+ def next(self):
+ pass
+
+class TrainIdler(Idler):
+ def __init__(self, v):
+ self.idle_state = 0
+ self.v = v
+
+ def put_shark(self, s, l):
+ if self.s[l] == ' ':
+ self.s[l] = s
+ elif self.s[l] == 'X':
+ self.s[l] = '*'
+ else:
+ self.s[l] = 'X'
+
+ def next(self):
+ # does the next stage of a dance
+ self.s = [' ']*10
+ shark1 = self.idle_state % 18
+ if shark1 < 9:
+ self.put_shark('^', shark1)
+ else:
+ self.put_shark('^', 18-shark1)
+
+ shark2 = ((self.idle_state+4) % 36)/2
+ if shark2 < 9:
+ self.put_shark('<', shark2)
+ else:
+ self.put_shark('<', 18-shark2)
+
+ shark3 = ((self.idle_state+7) % 54)/3
+ if shark3 < 9:
+ self.put_shark('>', 9-shark3)
+ else:
+ self.put_shark('>', 9-(18-shark3))
+
+ train1 = ((self.idle_state%(18*36)))
+ train1_start = 122
+ if train1 > train1_start and train1 < train1_start+(10*2):
+ for i in range(5):
+ ptr = i+train1-train1_start-5
+ if ptr >= 0 and ptr < 10: self.s[ptr] = '#'
+
+ train2 = ((self.idle_state%(18*36)))
+ train2_start = 400
+ if train2 > train2_start and train2 < train2_start+(10*2):
+ for i in range(5):
+ ptr = i+train2-train2_start-5
+ if ptr >= 0 and ptr < 10: self.s[9-ptr] = '#'
+
+ train3 = ((self.idle_state%(18*36)))
+ train3_start = 230
+ if train3 > train3_start and train3 < train3_start+(10*2):
+ for i in range(10):
+ ptr = i+train3-train3_start-10
+ if ptr >= 0 and ptr < 10: self.s[ptr] = '-'
+
+ self.v.display(string.join(self.s, ''))
+ self.idle_state += 1
+ self.idle_state %= 18*36*54
+
+class GrayIdler(Idler):
+ def __init__(self, v, one=None, zero=None):
+ self.bits = 8
+ self.size = 1 << self.bits
+ self.i = 0
+ self.grayCode = 0
+ self.v = v
+ self.one = one
+ self.zero = zero
+
+ def next(self):
+ output = self.do_next_state()
+ # does the next stage of a dance
+ if self.zero:
+ output = string.replace(output, "0", self.zero)
+ if self.one:
+ output = string.replace(output, "1", self.one)
+ self.v.display(" %8.8s " % (output))
+ self.i = (self.i + 1) % self.size
+
+ def do_next_state(self):
+ self.grayCode = self.i ^ (self.i >> 1)
+ output = self.dec2bin(self.grayCode)
+
+ return "0"*(self.bits-len(output))+output
+
+
+ def dec2bin(self,num):
+ """Convert long/integer number to binary string.
+
+ E.g. dec2bin(12) ==> '1100'.
+
+ from http://starship.python.net/~gherman/playground/decbingray/decbingray.py"""
+
+ assert num >= 0, "Decimal number must be >= 0!"
+
+ # Gracefully handle degenerate case.
+ # (Not really needed, but anyway.)
+ if num == 0:
+ return '0'
+
+ # Find highest value bit.
+ val, j = 1L, 1L
+ while val < num:
+ val, j = val*2L, j+1L
+
+ # Convert.
+ bin = ''
+ i = j - 1
+ while i + 1L:
+ k = pow(2L, i)
+ if num >= k:
+ bin = bin + '1'
+ num = num - k
+ else:
+ if len(bin) > 0:
+ bin = bin + '0'
+ i = i - 1L
+
+ return bin
+
+
+