#!/usr/bin/env python

# Script to read M. Rubinstein's modular polynomials saved in
# "compressed binary" form.  See:
#
#    http://www.math.uwaterloo.ca/~mrubinst/modularpolynomials/phi_l.html
#
# -- reads a ".bic" file and prints out the coefficients of the mod. pol.
#
# It can be used as:
# 
#  bic2dec.py  phi_2.bic phi_2.dec
#  bic2dec.py  phi_2.bic                (prints to STDOUT)
#  bic2dec.py  < phi_2.bic > phi_2.dec

import struct, sys


case=len(sys.argv) # no. of command line paramenters

if case > 3:
        print "Usage: read_phi <in_file> <out_file>"
elif case == 3:
        f = open(sys.argv[1], "rb")
        out = open(sys.argv[2],"w")
elif case == 2:
        f = open(sys.argv[1], "rb")
        out = sys.stdout
else: # case == 1
        f = sys.stdin
        out = sys.stdout

while True:

	# reads "len"
	header = f.read(4) 

	if len(header) == 0:
		break #EOF
	
	# convert to an integer
	#
	# note that in principle "i" is unsgined,
	# but we get the correct sign this way...
	len_array = struct.unpack("i", header)[0]


	if len_array != 0:
		# non-zero coefficient

		# read other terms
		rest = f.read(6)
		
		# "H" = short int. (2 bytes)
		e2, e3, e5 = struct.unpack("HHH", rest)

		# print(len_array, e2, e3, e5)

		# get the sign
		if len_array > 0:
			sign=1
		else:
			sign=-1
			
		# terms of the sum in an array of bytes
		byte_array = f.read(abs(len_array))

		# term is the last term of the product
		# that gives the coefficient (i.e., the sum)
		term, i = 0, 0
			
		for b in byte_array:
			bi = struct.unpack("B", b)[0]
			term+=bi*(256**i)
			i+=1

		# coefficient!
		# print(sign*(2**e2)*(3**e3)*(5**e5)*term)
                out.write(str(sign*(2**e2)*(3**e3)*(5**e5)*term) + "\n")

	else:

		# coefficient is zero
		# print(0)
                out.write(str(0) + "\n")

f.close()
out.close()