def compress(dic, consts):
bitstream.start(sys.argv[2], sys.argv[3])
buf = bitstream.read(consts['max'])
while buf != []:
# find matches and encode
match = match_buffers(dic, buf)
length = encode(match[0], match[1], dic, buf, consts)
# slide the window
del dic[:length]
dic.extend(buf[:length])
del buf[:length]
buf.extend(bitstream.read(length))
def decompress(dic, consts):
bitstream.start(sys.argv[2], sys.argv[3])
buf = ['filler']
while buf != []:
flag = bitstream.read(1)
if flag == [47]: #unencoded
buf = bitstream.read(consts['max'])
else: # encoded
break
# slide the window
del dic[:len(buf)]
dic.extend(buf)
bitstream.write(buf)
def decompress(dic, consts):
bitstream.start(sys.argv[2], sys.argv[3])
buf = ['filler']
while buf != []:
flag = bitstream.read(1)
if flag == [47]: #unencoded
buf = bitstream.read(consts['max'])
else: # encoded
break
# slide the window
del dic[:len(buf)]
dic.extend(buf)
bitstream.write(buf)
consts = {'min':16, # minimum match size; any less is not worth encoding
'max':23, # maximum match size
'dic':4096, # dictionary size
'posbits':12, # number of bits to encode position
'lenbits':3, # of bits to encode range
'uncoded':47, # uncoded flag
'coded':46,} # encoded flag
bitstream.start('dictionary', None)
dic = bitstream.read(consts['dic'])
if sys.argv[1] == '-c':
compress(dic, consts)
elif sys.argv[1] == '-d':
decompress(dic, consts)
else:
print('Usage: {0} -(c/d) <infile> <outfile>'.format(sys.argv[0]))