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brotli/research/brotlidump.py
Daniel Chýlek b5033d0e1e Fix brotlidump.py crashing when complex prefix code has exactly 1 non-zero code length (#635) 
According to the format specification regarding complex prefix codes:

> If there are at least two non-zero code lengths, any trailing zero
> code lengths are omitted, i.e., the last code length in the
> sequence must be non-zero.  In this case, the sum of (32 >> code
> length) over all the non-zero code lengths must equal to 32.

> If the lengths have been read for the entire code length alphabet
> and there was only one non-zero code length, then the prefix code
> has one symbol whose code has zero length.

The script does not handle a case where there is just 1 non-zero code
length where the sum rule doesn't apply, which causes a StopIteration
exception when it attempts to read past the list boundaries.

An example of such file is tests/testdata/mapsdatazrh.compressed. I made
sure this change doesn't break anything by processing all *.compressed
files from the testdata folder with no thrown exceptions.
2018-02-08 12:48:24 +01:00

2363 lines
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#!python3
"""Program to dump contents of Brotli compressed files showing the compression format.
Jurjen N.E. Bos, 2016.
I found the following issues with the Brotli format:
- The distance alphabet has size 16+(48<<POSTFIX),
but the last symbols are useless.
It could be lowered to 16+(44-POSTFIX<<POSTFIX), and this could matter.
- The block type code is useless if NBLTYPES==2, you would only need 1 symbol
anyway, so why don't you just switch to "the other" type?
"""
import struct
from operator import itemgetter, methodcaller
from itertools import accumulate, repeat
from collections import defaultdict, deque
from functools import partial
class InvalidStream(Exception): pass
#lookup table
L, I, D = "literal", "insert&copy", "distance"
pL, pI, pD = 'P'+L, 'P'+I, 'P'+D
def outputCharFormatter(c):
"""Show character in readable format
"""
#TODO 2: allow hex only output
if 32<c<127: return chr(c)
elif c==10: return '\\n'
elif c==13: return '\\r'
elif c==32: return '" "'
else: return '\\x{:02x}'.format(c)
def outputFormatter(s):
"""Show string or char.
"""
result = ''
def formatSubString(s):
for c in s:
if c==32: yield ' '
else: yield outputCharFormatter(c)
if len(result)<200: return ''.join(formatSubString(s))
else:
return ''.join(formatSubString(s[:100]))+'...'+ \
''.join(formatSubString(s[-100:]))
class BitStream:
"""Represent a bytes object. Can read bits and prefix codes the way
Brotli does.
"""
def __init__(self, byteString):
self.data = byteString
#position in bits: byte pos is pos>>3, bit pos is pos&7
self.pos = 0
def __repr__(self):
"""Representation
>>> olleke
BitStream(pos=0:0)
"""
return "BitStream(pos={:x}:{})".format(self.pos>>3, self.pos&7)
def read(self, n):
"""Read n bits from the stream and return as an integer.
Produces zero bits beyond the stream.
>>> olleke.data[0]==27
True
>>> olleke.read(5)
27
>>> olleke
BitStream(pos=0:5)
"""
value = self.peek(n)
self.pos += n
if self.pos>len(self.data)*8:
raise ValueError('Read past end of stream')
return value
def peek(self, n):
"""Peek an n bit integer from the stream without updating the pointer.
It is not an error to read beyond the end of the stream.
>>> olleke.data[:2]==b'\x1b\x2e' and 0x2e1b==11803
True
>>> olleke.peek(15)
11803
>>> hex(olleke.peek(32))
'0x2e1b'
"""
#read bytes that contain the data: self.data[self.pos>>3:self.pos+n+7>>3]
#convert to int: int.from_bytes(..., 'little')
#shift out the bits from the first byte: >>(self.pos&7)
#mask unwanted bits: & (1<<n)-1
return int.from_bytes(
self.data[self.pos>>3:self.pos+n+7>>3],
'little')>>(self.pos&7) & (1<<n)-1
def readBytes(self, n):
"""Read n bytes from the stream on a byte boundary.
"""
if self.pos&7: raise ValueError('readBytes: need byte boundary')
result = self.data[self.pos>>3:(self.pos>>3)+n]
self.pos += 8*n
return result
#-----------------------Symbol-------------------------------------------
class Symbol:
"""A symbol in a code.
Refers back to the code that contains it.
Index is the place in the alphabet of the symbol.
"""
__slots__ = 'code', 'index'
def __init__(self, code, value):
self.code = code
self.index = value
def __repr__(self):
return 'Symbol({}, {})'.format(self.code.name, self.index)
def __len__(self):
"""Number of bits in the prefix notation of this symbol
"""
return self.code.length(self.index)
def __int__(self):
return self.index
#these routines call equivalent routine in Code class
def bitPattern(self):
"""Value of the symbol in the stream
"""
return self.code.bitPattern(self.index)
def extraBits(self):
"""Number of extra bits to read for this symbol
"""
return self.code.extraBits(self.index)
def __str__(self):
"""Short descriptor of the symbol without extra bits.
"""
return self.code.mnemonic(self.index)
#requiring optional extra bits, if self.code supports them
def value(self, extra=None):
"""The value used for processing. Can be a tuple.
with optional extra bits
"""
if isinstance(self.code, WithExtra):
if not 0<=extra<1<<self.extraBits():
raise ValueError("value: extra value doesn't fit in extraBits")
return self.code.value(self.index, extra)
if extra is not None:
raise ValueError('value: no extra bits for this code')
return self.code.value(self.index)
def explanation(self, extra=None):
"""Long explanation of the value from the numeric value
with optional extra bits
Used by Layout.verboseRead when printing the value
"""
if isinstance(self.code, WithExtra):
return self.code.callback(self, extra)
return self.code.callback(self)
#========================Code definitions==================================
class RangeDecoder:
"""A decoder for the Code class that assumes the symbols
are encoded consecutively in binary.
It all depends on the "alphabetSize" property.
The range runs from 0 to alphabetSize-1.
This is the default decoder.
"""
def __init__(self, *, alphabetSize=None, bitLength=None, **args):
if bitLength is not None: alphabetSize = 1<<bitLength
if alphabetSize is not None:
self.alphabetSize = alphabetSize
self.maxLength = (alphabetSize-1).bit_length()
def __len__(self):
return self.alphabetSize
def __iter__(self):
"""Produce all symbols.
"""
return map(partial(Symbol, self), range(len(self)))
def __getitem__(self, index):
if index>=self.alphabetSize: raise ValueError('index out of range')
return Symbol(self, index)
def bitPattern(self, index):
return '{:0{}b}'.format(index, self.maxLength)
def length(self, index):
"""Encoding length of given symbol.
Does not depend on index in this case.
"""
return self.maxLength
def decodePeek(self, data):
"""Find which symbol index matches the given data (from peek, as a number)
and return the number of bits decoded.
Can also be used to figure out length of a symbol.
"""
return self.maxLength, Symbol(self, data&(1<<self.maxLength)-1)
class PrefixDecoder:
"""A decoder for the Code class that uses a prefix code.
The code is determined by encoding:
encode[p] gives the index corresponding to bit pattern p.
Used setDecode(decodeTable) to switch the decoder from the default
to a prefix decoder, or pass decodeTable at init.
You can also use setLength(lengthTable)
to define the encoding from the lengths.
The set of symbol values does not need to be consecutive.
"""
def __init__(self, *, decodeTable=None, **args):
if decodeTable is not None: self.setDecode(decodeTable)
def __len__(self):
return len(self.decodeTable)
def __iter__(self):
def revBits(index):
return self.bitPattern(index)[::-1]
return (
Symbol(self, index)
for index in sorted(self.decodeTable.values(), key=revBits)
)
def __getitem__(self, index):
if index not in self.lengthTable:
raise ValueError('No symbol {}[{}]'.format(
self.__class__.__name__, index))
return Symbol(self, index)
def bitPattern(self, index):
bits = next(b for (b,s) in self.decodeTable.items() if s==index)
return '{:0{}b}'.format(bits, self.length(index))
def length(self, index):
"""Encoding length of given symbol.
"""
return self.lengthTable[index]
def decodePeek(self, data):
"""Find which symbol index matches the given data (from peek, as a number)
and return the number of bits decoded.
Can also be used to figure out length of a symbol.
"""
#do binary search for word length
#invariant: lo<=length<=hi
lo, hi = self.minLength, self.maxLength
while lo<=hi:
mid = lo+hi>>1
#note lo<=mid<hi at this point
mask = (1<<mid)-1
#lets see what happens if we guess length is mid
try: index = self.decodeTable[data&mask]
except KeyError:
#too many bits specified, reduce estimated length
hi = mid-1
continue
#we found a symbol, but there could be a longer match
symbolLength = self.lengthTable[index]
if symbolLength<=mid:
#all bits match, symbol must be right
return symbolLength, Symbol(self, index)
#there must be more bits to match
lo = mid+1
return lo, Symbol(self, index)
#routine to set up the tables
def setDecode(self, decodeTable):
"""Store decodeTable,
and compute lengthTable, minLength, maxLength from encodings.
"""
self.decodeTable = decodeTable
#set of symbols with unknown length
todo = set(decodeTable)
#bit size under investigation
maskLength = 0
lengthTable = {}
while todo:
mask = (1<<maskLength)-1
#split the encodings that we didn't find yet using b bits
splitSymbols = defaultdict(list)
for s in todo: splitSymbols[s&mask].append(s)
#unique encodings have a length of maskLength bits
#set length, and remove from todo list
for s,subset in splitSymbols.items():
if len(subset)==1:
lengthTable[self.decodeTable[s]] = maskLength
todo.remove(s)
#now investigate with longer mask
maskLength +=1
#save result
self.lengthTable = lengthTable
self.minLength = min(lengthTable.values())
self.maxLength = max(lengthTable.values())
self.switchToPrefix()
def setLength(self, lengthTable):
"""Given the bit pattern lengths for symbols given in lengthTable,
set decodeTable, minLength, maxLength
"""
self.lengthTable = lengthTable
self.minLength = min(lengthTable.values())
self.maxLength = max(lengthTable.values())
#compute the backwards codes first; then reverse them
#compute (backwards) first code for every separate lengths
nextCodes = []
#build codes for each length, from right to left
code = 0
for bits in range(self.maxLength+1):
code <<= 1
nextCodes.append(code)
code += sum(x==bits for x in lengthTable.values())
self.decodeTable = {}
#count codes for each length, and store reversed in the table
for symbol in sorted(lengthTable):
bits = lengthTable[symbol]
bitpattern = '{:0{}b}'.format(nextCodes[bits], bits)
self.decodeTable[int(bitpattern[::-1], 2)] = symbol
nextCodes[bits] += 1
self.switchToPrefix()
def switchToPrefix(self):
"""This routine makes sure the prefix decoder is activated.
"""
self.mode = PrefixDecoder
class Code(RangeDecoder, PrefixDecoder):
"""An alphabet of symbols, that can be read from a stream.
If you use setDecode or setLength, you have a prefix code,
otherwise you have a range code.
Features:
code[index] produces symbol with given index
value(index): value of symbol
mnemonic(index): short description of symbol
explanation(index): show meaning of symbol, shown in Layout.verboseRead
iter(code): produce all symbols in some order
name: show as context in Layout.verboseRead
"""
name = '?'
#callback is a function that gets the symbol and the extra bits
#default callback calls explanation
def __init__(self, name=None, *, callback=None, description='', **args):
"""Don't forget to set either alphabetSize or decodeTable
"""
#set name when provided, otherwise take class variable
if name is not None: self.name = name
if callback is not None: self.callback = callback
self.description = description
#mode switch
if 'bitLength' in args or 'alphabetSize' in args:
self.mode = RangeDecoder
RangeDecoder.__init__(self, **args)
elif 'decodeTable' in args:
self.mode = PrefixDecoder
PrefixDecoder.__init__(self, **args)
else:
super().__init__(**args)
def __repr__(self):
return self.__class__.__name__+' '+self.name
#the routines that get switched between RangeDecoder and PrefixDecoder
def __len__(self): return self.mode.__len__(self)
def __iter__(self): return self.mode.__iter__(self)
def __getitem__(self, index): return self.mode.__getitem__(self, index)
def bitPattern(self, index): return self.mode.bitPattern(self, index)
def length(self, index): return self.mode.length(self, index)
def decodePeek(self, data): return self.mode.decodePeek(self, data)
#general routines
def value(self, index, extra=None):
"""Get value of symbol for computations.
Override where needed.
"""
if extra is not None:
raise ValueError('value: no extra for this symbol')
return index
def mnemonic(self, index):
"""Give mnemonic of symbol.
Override where needed.
"""
return str(self.value(index))
def callback(self, symbol):
return self.explanation(symbol.index)
def explanation(self, index):
"""Long explanation of the value from the numeric value
This is a default routine.
You can customize in three ways:
- set description to add some text
- override to get more control
- set callback to make it dependent on you local variables
"""
value = self.value(index)
return '{0}{1}: {2}'.format(
self.description and self.description+': ',
self.bitPattern(index),
value,
)
def extraBits(self, index):
return 0
#Routines that use the decode interface
def showCode(self, width=80):
"""Show all words of the code in a nice format.
"""
#make table of all symbols with binary strings
symbolStrings = [
(self.bitPattern(s.index), self.mnemonic(s.index))
for s in self
]
#determine column widths the way Lisp programmers do it
leftColWidth, rightColWidth = map(max, map(
map,
repeat(len),
zip(*symbolStrings)
))
colwidth = leftColWidth+rightColWidth
columns = 81//(colwidth+2)
rows = -(-len(symbolStrings)//columns)
def justify(bs):
b,s = bs
return b.rjust(leftColWidth)+':'+s.ljust(rightColWidth)
for i in range(rows):
print(' '.join(map(justify, symbolStrings[i::rows])).rstrip())
def readTuple(self, stream):
"""Read symbol from stream. Returns symbol, length.
"""
length, symbol = self.decodePeek(stream.peek(self.maxLength))
stream.pos += length
return length, symbol
def readTupleAndExtra(self, stream):
return self.readTuple(stream)+(0, None)
class WithExtra(Code):
"""Extension for Code so that symbol may have extra bits associated.
If you supply an extraTable, you can use extraBits
You can define an extraTable,
which allows to call extraBits to get the number of extraBits.
Otherwise, you can supply extraBits yourself.
Routine readTupleAndExtra now reads the extra bits too.
Value probably needs to be overridden; see Enumerator.
Note: this does not give you an decodeTable.
"""
#redefine these if you don't want to use an extraTable
def extraBits(self, index):
"""Get the number of extra bits for this symbol.
"""
return self.extraTable[index]
def mnemonic(self, index):
"""This value must be independent of extra.
"""
return str(index)
def readTupleAndExtra(self, stream):
"""Read symbol and extrabits from stream.
Returns symbol length, symbol, extraBits, extra
>>> olleke.pos = 6
>>> MetablockLengthAlphabet().readTupleAndExtra(olleke)
(2, Symbol(MLEN, 4), 16, 46)
"""
length, symbol = self.decodePeek(stream.peek(self.maxLength))
stream.pos += length
extraBits = self.extraBits(symbol.index)
return length, symbol, extraBits, stream.read(extraBits)
def explanation(self, index, extra=None):
"""Expanded version of Code.explanation supporting extra bits.
If you don't supply extra, it is not mentioned.
"""
extraBits = 0 if extra is None else self.extraBits(index)
if not hasattr(self, 'extraTable'):
formatString = '{0}{3}'
lo = hi = value = self.value(index, extra)
elif extraBits==0:
formatString = '{0}{2}: {3}'
lo, hi = self.span(index)
value = lo
else:
formatString = '{0}{1} {2}: {3}-{4}; {3}+{5}={6}'
lo, hi = self.span(index)
value = lo+extra
return formatString.format(
self.description and self.description+': ',
'x'*extraBits,
self.bitPattern(index),
lo, hi,
extra,
value,
)
def callback(self, symbol, extra):
return self.explanation(symbol.index, extra)
class BoolCode(Code):
"""Same as Code(bitLength=1), but shows a boolean.
"""
def __init__(self, name=None, **args):
super().__init__(name, bitLength=1, **args)
def value(self, index, extra=None):
return bool(super().value(index, extra))
class Enumerator(WithExtra):
"""Code that is defined by the ExtraTable.
extraTable is a class variable that contains
the extraBits of the symbols from 0
value0 contains the value of symbol 0
encodings is not neccessary, but allowed.
Note: place for FixedCode to make sure extraBits works
"""
def __init__(self, name=None, **args):
#if there is no decodeTable to determine length, compute it ourselves
if 'decodeTable' not in args:
args['alphabetSize'] = len(self.extraTable)
super().__init__(name, **args)
def __len__(self):
return len(self.extraTable)
def __getitem__(self, index):
"""Faster than PrefixDecoder
"""
if index>=len(self.extraTable):
raise ValueError("No symbol {}[{}]".format(
self.__class__.__name__, index))
return Symbol(self, index)
def value(self, index, extra):
"""Override if you don't define value0 and extraTable
"""
lower, upper = self.span(index)
value = lower+(extra or 0)
if value>upper:
raise ValueError('value: extra out of range')
return value
def span(self, index):
"""Give the range of possible values in a tuple
Useful for mnemonic and explanation
"""
lower = self.value0+sum(1<<x for x in self.extraTable[:index])
upper = lower+(1<<self.extraTable[index])
return lower, upper-1
#======================Code subclasses======================================
#Alphabets used in the metablock header----------------------------------
#For prefix codes
class PrefixCodeHeader(WithExtra):
"""Header of prefix codes.
"""
def __init__(self, codename):
super().__init__('PFX', bitLength=2)
#this is the name of the code that it describes
self.codename = codename
def extraBits(self, index):
return 2 if index==1 else 0
def value(self, index, extra):
"""Returns ('Simple', #codewords) or ('Complex', HSKIP)
"""
if index==1:
if extra>3:
raise ValueError('value: extra out of range')
return 'Simple', extra+1
if extra:
raise ValueError('value: extra out of range')
return 'Complex', index
def explanation(self, index, extra):
if index==1:
return '{} is simple with {} code word{}'.format(
self.codename, extra+1, 's' if extra else '')
lengths = [1, 2, 3, 4, 0, 5, 17, 6]
return '{} is complex with lengths {}...'.format(
self.codename,
','.join(
map(str, lengths[index:index+5]))
)
class TreeShapeAlhabet(BoolCode):
"""The bit used to indicate if four word code is "deep" or "wide"
"""
name = 'SHAPE'
def value(self, index):
return [(2,2,2,2), (1,2,3,3)][index]
def explanation(self, index):
return str(bool(index))+': lengths {},{},{},{}'.format(*self.value(index))
class LengthOfLengthAlphabet(Code):
"""For use in decoding complex code descriptors.
>>> lengthOfLengthAlphabet = LengthOfLengthAlphabet('')
>>> print(lengthOfLengthAlphabet[2])
coded with 2 bits
>>> len(lengthOfLengthAlphabet[0])
2
>>> [len(lengthOfLengthAlphabet[x]) for x in range(6)]
[2, 4, 3, 2, 2, 4]
>>> lengthOfLengthAlphabet.showCode()
00:skipped 01:coded with 4 bits 0111:coded with 1 bits
10:coded with 3 bits 011:coded with 2 bits 1111:coded with 5 bits
"""
decodeTable = {
0b00:0, 0b10:3,
0b0111:1, 0b01:4,
0b011:2, 0b1111:5,
}
def __init__(self, name=None, **args):
super().__init__(name, decodeTable=self.decodeTable, **args)
def mnemonic(self, index):
if index==0: return 'skipped'
return 'coded with {} bits'.format(index)
def explanation(self, index, extra=None):
return self.description+': '+self.mnemonic(index)
class LengthAlphabet(WithExtra):
"""Length of symbols
Used during construction of a code.
"""
def __init__(self, name):
super().__init__(name, alphabetSize=18)
def extraBits(self, index):
return {16:2, 17:3}.get(index, 0)
def mnemonic(self, index):
if index==0: return 'unused'
elif index==16: return 'rep xx'
elif index==17: return 'zero xxx'
else: return 'len {}'.format(index)
def explanation(self, index, extra):
return self.description.format(self[index], extra)
def value(self, index, extra):
#the caller got the length already, so extra is enough
return extra
#Stream header
class WindowSizeAlphabet(Code):
"""The alphabet used for window size in the stream header.
>>> WindowSizeAlphabet()[10].explanation()
'windowsize=(1<<10)-16=1008'
"""
decodeTable = {
0b0100001: 10, 0b1100001: 14, 0b0011: 18, 0b1011: 22,
0b0110001: 11, 0b1110001: 15, 0b0101: 19, 0b1101: 23,
0b1000001: 12, 0b0: 16, 0b0111: 20, 0b1111: 24,
0b1010001: 13, 0b0000001: 17, 0b1001: 21,
0b0010001: None,
}
name = 'WSIZE'
def __init__(self, name=None):
super().__init__(name, decodeTable=self.decodeTable)
def value(self, index):
#missing value gives index None
if index is None: return None
return (1<<index)-16
def explanation(self, index):
return 'windowsize=(1<<{})-16={}'.format(
index, (1<<index)-16)
#Metablock
class MetablockLengthAlphabet(WithExtra):
"""Used for the meta block length;
also indicates a block with no data
>>> metablockLengthAlphabet = MetablockLengthAlphabet()
>>> metablockLengthAlphabet[0]; str(metablockLengthAlphabet[0])
Symbol(MLEN, 0)
'empty'
>>> metablockLengthAlphabet[3]
Traceback (most recent call last):
...
ValueError: No symbol MetablockLengthAlphabet[3]
>>> print(metablockLengthAlphabet[4])
hhhh00
>>> metablockLengthAlphabet[4].value(0x1000)
4097
>>> metablockLengthAlphabet[5].value(0x1000)
Traceback (most recent call last):
...
InvalidStream: Zeros in high nibble of MLEN
>>> metablockLengthAlphabet[5].explanation(0x12345)
'data length: 12345h+1=74566'
>>> metablockLengthAlphabet.showCode()
00:hhhh00 10:hhhhhh10 01:hhhhh01 11:empty
"""
decodeTable = {0b11:0, 0b00:4, 0b01:5, 0b10:6}
name = 'MLEN'
def __init__(self, name=None):
super().__init__(name, decodeTable=self.decodeTable)
def extraBits(self, index):
return index*4
def mnemonic(self, index):
if index==0: return 'empty'
return 'h'*(self.extraBits(index)//4)+self.bitPattern(index)
def value(self, index, extra):
extraBits = self.extraBits(index)
if not 0<=extra<1<<extraBits:
raise ValueError('value: extra out of range')
if index==0: return 0
if index>4 and extra>>extraBits-4==0: raise InvalidStream(
'Zeros in high nibble of MLEN')
return extra+1
def explanation(self, index, extra):
if index==0: return '11: empty block'
extraBits = self.extraBits(index)
return 'data length: {:0{}x}h+1={}'.format(extra, extraBits//4, extra+1)
class ReservedAlphabet(BoolCode):
"""The reserved bit that must be zero.
"""
name = 'RSVD'
def value(self, index):
if index: raise ValueError('Reserved bit is not zero')
def explanation(self, index):
return 'Reserved (must be zero)'
class FillerAlphabet(Code):
def __init__(self, *, streamPos):
super().__init__('SKIP', bitLength=(-streamPos)&7)
def explanation(self, index):
return '{} bit{} ignored'.format(
self.length(index),
'' if self.length(index)==1 else 's',
)
class SkipLengthAlphabet(WithExtra):
"""Used for the skip length in an empty metablock
>>> skipLengthAlphabet = SkipLengthAlphabet()
>>> skipLengthAlphabet[0]; str(skipLengthAlphabet[0])
Symbol(SKIP, 0)
'empty'
>>> skipLengthAlphabet[4]
Traceback (most recent call last):
...
ValueError: index out of range
>>> print(skipLengthAlphabet[3])
hhhhhh11
>>> skipLengthAlphabet[2].value(0x1000)
4097
>>> skipLengthAlphabet[3].value(0x1000)
Traceback (most recent call last):
...
InvalidStream: Zeros in high byte of SKIPBYTES
>>> skipLengthAlphabet[3].explanation(0x12345)
'skip length: 12345h+1=74566'
>>> skipLengthAlphabet.showCode()
00:empty 01:hh01 10:hhhh10 11:hhhhhh11
"""
def __init__(self):
super().__init__('SKIP', bitLength=2)
def extraBits(self, index):
return index*8
def mnemonic(self, index):
if index==0: return 'empty'
return 'h'*(self.extraBits(index)//4)+self.bitPattern(index)
def value(self, index, extra):
extraBits = self.extraBits(index)
if not 0<=extra<1<<extraBits:
raise ValueError('value: extra out of range')
if index==0: return 0
if index>1 and extra>>extraBits-8==0:
raise InvalidStream('Zeros in high byte of SKIPBYTES')
return extra+1
def explanation(self, index, extra):
if index==0: return '00: no skip'
extraBits = self.extraBits(index)
return 'skip length: {:{}x}h+1={}'.format(extra, extraBits//8, extra+1)
class TypeCountAlphabet(Enumerator):
"""Used for giving block type counts and tree counts.
>>> TypeCountAlphabet(description='').showCode()
0:0 0101:xx,0101 1011:xxxxx,1011
0001:0001 1101:xxxxxx,1101 0111:xxx,0111
1001:xxxx,1001 0011:x,0011 1111:xxxxxxx,1111
"""
decodeTable = {
0b0: 0, 0b1001: 5,
0b0001: 1, 0b1011: 6,
0b0011: 2, 0b1101: 7,
0b0101: 3, 0b1111: 8,
0b0111: 4,
}
value0 = 1
extraTable = [0, 0, 1, 2, 3, 4, 5, 6, 7]
name = 'BT#'
def __init__(self, name=None, *, description):
super().__init__(
name,
decodeTable=self.decodeTable,
description=description)
def mnemonic(self, index):
if index==0: return '0'
if index==1: return '0001'
return 'x'*(self.extraBits(index))+','+self.bitPattern(index)
def explanation(self, index, extra):
value = self.value(index, extra)
description = self.description
if value==1: description = description[:-1]
return '{}: {} {}'.format(
self.mnemonic(index),
value,
description)
class BlockTypeAlphabet(Code):
"""The block types; this code works for all three kinds.
>>> b = BlockTypeAlphabet('T', NBLTYPES=5)
>>> print(*(x for x in b))
prev +1 #0 #1 #2 #3 #4
"""
def __init__(self, name, NBLTYPES, **args):
super().__init__(name, alphabetSize=NBLTYPES+2, **args)
self.NBLTYPES = NBLTYPES
def mnemonic(self, index):
if index==0: return 'prev'
elif index==1: return '+1'
else: return '#'+str(index-2)
def value(self, index):
return index-2
def explanation(self, index):
if index==0: return '0: previous'
elif index==1: return '1: increment'
else: return 'Set block type to: '+str(index-2)
class BlockCountAlphabet(Enumerator):
"""Block counts
>>> b = BlockCountAlphabet('L')
>>> print(b[25])
[24*x]: BC16625-16793840
"""
value0 = 1
extraTable = [2,2,2,2,3, 3,3,3,4,4, 4,4,5,5,5, 5,6,6,7,8, 9,10,11,12,13, 24]
def __init__(self, name, **args):
super().__init__(name, alphabetSize=26, **args)
def mnemonic(self, index):
extraBits = self.extraBits(index)
return '{}: BC{}-{}'.format(
'x'*extraBits if index<5 else '[{}*x]'.format(extraBits),
*self.span(index))
def explanation(self, index, extra):
return 'Block count: '+super().explanation(index, extra)
class DistanceParamAlphabet(WithExtra):
"""The distance parameters NPOSTFIX and NDIRECT.
Although these are treated as two in the description, this is easier.
"""
def __init__(self):
super().__init__('DIST', bitLength=2)
def extraBits(self, index):
return 4
def value(self, index, extra):
"""Returns NPOSTFIX and NDIRECT<<NPOSTFIX
"""
if extra>15:
raise ValueError('value: extra out of range')
return index, extra<<index
def explanation(self, index, extra):
return '{} postfix bits and {:04b}<<{}={} direct codes'.format(
index, extra, index, extra<<index)
def mnemonic(self, index):
return 'PF'+str(index)
class LiteralContextMode(Code):
"""For the literal context modes.
>>> LiteralContextMode().showCode()
00:LSB6 01:MSB6 10:UTF8 11:Signed
>>> LiteralContextMode().explanation(2)
'Context mode for type 9: 2(UTF8)'
"""
def __init__(self, *, number=9):
super().__init__('LC'+str(number), bitLength=2)
self.number = number
def mnemonic(self, index):
return ['LSB6', 'MSB6', 'UTF8', 'Signed'][index]
def explanation(self, index):
return 'Context mode for type {}: {}({})'.format(
self.number,
index,
self.mnemonic(index))
class RLEmaxAlphabet(Enumerator):
"""Used for describing the run length encoding used for describing context maps.
>>> RLEmaxAlphabet().showCode()
0:1 1:more
"""
value0 = 0
extraTable = [0, 4]
name = 'RLE#'
def mnemonic(self, index):
return ['1', 'more'][index]
def explanation(self, index, extra):
description = self.description and self.description+': '
if index==0: return description+'No RLE coding'
return '{}xxxx 1: RLEMAX={}'.format(description, extra+1)
class TreeAlphabet(WithExtra):
"""The alphabet to enumerate entries (called trees) in the context map.
parameters are RLEMAX and NTREES
>>> t = TreeAlphabet('', RLEMAX=3, NTREES=5)
>>> len(t)
8
>>> print(t[2])
xx+4 zeroes
>>> t[3].explanation(2)
'8+010=10 zeroes'
>>> t[0].value(0)
(1, 0)
"""
name = 'CMI'
def __init__(self, name=None, *, RLEMAX, NTREES, **args):
super().__init__(name, alphabetSize=RLEMAX+NTREES, **args)
self.RLEMAX = RLEMAX
self.NTREES = NTREES
def extraBits(self, index):
if 0<index<=self.RLEMAX: return index
return 0
def mnemonic(self, index):
if index==0: return 'map #0'
if index<=self.RLEMAX:
return '{}+{} zeroes'.format('x'*index, 1<<index)
return 'map #{}'.format(index-self.RLEMAX)
def value(self, index, extra):
"""Give count and value."""
index = index
if index==0: return 1, 0
if index<=self.RLEMAX: return (1<<index)+extra, 0
return 1, index-self.RLEMAX
def explanation(self, index, extra):
description = self.description and self.description+': '
if index==0: return description+'map #0'
if index<=self.RLEMAX:
return '{}+{:0{}b}={} zeroes'.format(
(1<<index),
extra, self.extraBits(index),
(1<<index)+extra)
return '{}map #{}-{}={}'.format(
description,
index, self.RLEMAX, index-self.RLEMAX)
#Prefix alphabets for the data stream----------------------------------
class LiteralAlphabet(Code):
"""Alphabet of symbols.
"""
minLength = maxLength = 8
def __init__(self, number):
super().__init__('L'+str(number), alphabetSize=1<<8)
def mnemonic(self, index):
return outputCharFormatter(index)
def value(self, index, extra=None):
return index
def explanation(self, index, extra=None):
return self.mnemonic(index)
class InsertLengthAlphabet(Enumerator):
"""Intern code for insert counts
"""
value0 = 0
extraTable = [0,0,0,0,0, 0,1,1,2,2, 3,3,4,4,5, 5,6,7,8,9, 10,12,14,24]
class CopyLengthAlphabet(Enumerator):
value0 = 2
extraTable = [0,0,0,0,0, 0,0,0,1,1, 2,2,3,3,4, 4,5,5,6,7, 8,9,10,24]
class InsertAndCopyAlphabet(WithExtra):
"""The insert and copy code
>>> for x in range(0,704,704//13):
... print('{:10b}'.format(x), InsertAndCopyAlphabet()[x])
0 I0C2&D=0
110110 I6+xC8&D=0
1101100 I5C22+xxx&D=0
10100010 I4C4
11011000 I3C10+x
100001110 I14+xxC8
101000100 I10+xxC22+xxx
101111010 I98+xxxxxC14+xx
110110000 I6+xC70+xxxxx
111100110 I1090+[10*x]C8
1000011100 I26+xxxC326+[8*x]
1001010010 I322+[8*x]C14+xx
1010001000 I194+[7*x]C70+xxxxx
1010111110 I22594+[24*x]C1094+[10*x]
"""
insertLengthAlphabet = InsertLengthAlphabet(None)
copyLengthAlphabet = CopyLengthAlphabet(None)
def __init__(self, number=''):
super().__init__('IC'+str(number), bitLength=10)
def __len__(self):
return 704
def extraBits(self, index):
insertSymbol, copySymbol, dist0 = self.splitSymbol(index)
return InsertLengthAlphabet.extraTable[insertSymbol.index] + \
CopyLengthAlphabet.extraTable[copySymbol.index]
def splitSymbol(self, index):
"""Give relevant values for computations:
(insertSymbol, copySymbol, dist0flag)
"""
#determine insert and copy upper bits from table
row = [0,0,1,1,2,2,1,3,2,3,3][index>>6]
col = [0,1,0,1,0,1,2,0,2,1,2][index>>6]
#determine inserts and copy sub codes
insertLengthCode = row<<3 | index>>3&7
if row: insertLengthCode -= 8
copyLengthCode = col<<3 | index&7
return (
Symbol(self.insertLengthAlphabet, insertLengthCode),
Symbol(self.copyLengthAlphabet, copyLengthCode),
row==0
)
def mnemonic(self, index):
"""Make a nice mnemonic
"""
i,c,d0 = self.splitSymbol(index)
iLower, _ = i.code.span(i.index)
iExtra = i.extraBits()
cLower, _ = c.code.span(c.index)
cExtra = c.extraBits()
return 'I{}{}{}C{}{}{}{}'.format(
iLower,
'+' if iExtra else '',
'x'*iExtra if iExtra<6 else '[{}*x]'.format(iExtra),
cLower,
'+' if cExtra else '',
'x'*cExtra if cExtra<6 else '[{}*x]'.format(cExtra),
'&D=0' if d0 else '')
def value(self, index, extra):
i,c,d0 = self.splitSymbol(index)
iExtra = i.extraBits()
ce, ie = extra>>iExtra, extra&(1<<iExtra)-1
insert = i.value(ie)
copy = c.value(ce)
return insert, copy, d0
def explanation(self, index, extra):
insert, copy, d0 = self.value(index, extra)
if d0: return 'Literal: {}, copy: {}, same distance'.format(insert, copy)
else: return 'Literal: {}, copy: {}'.format(insert, copy)
class DistanceAlphabet(WithExtra):
"""Represent the distance encoding.
Dynamically generated alphabet.
This is what the documentation should have said:
Ignoring offsets for the moment, the "long" encoding works as follows:
Write the distance in binary as follows:
1xy..yz..z, then the distance symbol consists of n..nxz..z
Where:
n is one less than number of bits in y
x is a single bit
y..y are n+1 extra bits (encoded in the bit stream)
z..z is NPOSTFIX bits that are part of the symbol
The offsets are so as to start at the lowest useable value:
if 1xyyyyz = distance +(4<<POSTFIX)-NDIRECT-1
then n..nxz..z is symbol -NDIRECT-16
>>> d = DistanceAlphabet('D', NPOSTFIX=2, NDIRECT=10)
>>> print(d[4], d[17], d[34])
last-1 1 10xx00-5
>>> [str(d[x]) for x in range(26, 32)]
['10x00-5', '10x01-5', '10x10-5', '10x11-5', '11x00-5', '11x01-5']
"""
def __init__(self, number, *, NPOSTFIX, NDIRECT):
self.NPOSTFIX = NPOSTFIX
self.NDIRECT = NDIRECT
#set length
#Actually, not all symbols are used,
#only NDIRECT+16+(44-2*POSTFIX<<NPOSTFIX)
super().__init__('D'+str(number),
alphabetSize=self.NDIRECT+16+(48<<self.NPOSTFIX))
def extraBits(self, index):
"""Indicate how many extra bits are needed to interpret symbol
>>> d = DistanceAlphabet('D', NPOSTFIX=2, NDIRECT=10)
>>> [d[i].extraBits() for i in range(26)]
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
>>> [d[i].extraBits() for i in range(26,36)]
[1, 1, 1, 1, 1, 1, 1, 1, 2, 2]
"""
if index<16+self.NDIRECT: return 0
return 1 + ((index - self.NDIRECT - 16) >> (self.NPOSTFIX + 1))
def value(self, dcode, dextra):
"""Decode value of symbol together with the extra bits.
>>> d = DistanceAlphabet('D', NPOSTFIX=2, NDIRECT=10)
>>> d[34].value(2)
(0, 35)
"""
if dcode<16:
return [(1,0),(2,0),(3,0),(4,0),
(1,-1),(1,+1),(1,-2),(1,+2),(1,-3),(1,+3),
(2,-1),(2,+1),(2,-2),(2,+2),(2,-3),(2,+3)
][dcode]
if dcode<16+self.NDIRECT:
return (0,dcode-16)
#we use the original formulas, instead of my clear explanation
POSTFIX_MASK = (1 << self.NPOSTFIX) - 1
ndistbits = 1 + ((dcode - self.NDIRECT - 16) >> (self.NPOSTFIX + 1))
hcode = (dcode - self.NDIRECT - 16) >> self.NPOSTFIX
lcode = (dcode - self.NDIRECT - 16) & POSTFIX_MASK
offset = ((2 + (hcode & 1)) << ndistbits) - 4
distance = ((offset + dextra) << self.NPOSTFIX) + lcode + self.NDIRECT + 1
return (0,distance)
def mnemonic(self, index, verbose=False):
"""Give mnemonic representation of meaning.
verbose compresses strings of x's
"""
if index<16:
return ['last', '2last', '3last', '4last',
'last-1', 'last+1', 'last-2', 'last+2', 'last-3', 'last+3',
'2last-1', '2last+1', '2last-2', '2last+2', '2last-3', '2last+3'
][index]
if index<16+self.NDIRECT:
return str(index-16)
#construct strings like "1xx01-15"
index -= self.NDIRECT+16
hcode = index >> self.NPOSTFIX
lcode = index & (1<<self.NPOSTFIX)-1
if self.NPOSTFIX: formatString = '1{0}{1}{2:0{3}b}{4:+d}'
else: formatString = '1{0}{1}{4:+d}'
return formatString.format(
hcode&1,
'x'*(2+hcode>>1) if hcode<13 or verbose else '[{}*x]'.format(2+hcode>>1),
lcode, self.NPOSTFIX,
self.NDIRECT+1-(4<<self.NPOSTFIX))
def explanation(self, index, extra):
"""
>>> d = DistanceAlphabet('D', NPOSTFIX=2, NDIRECT=10)
>>> d[55].explanation(13)
'11[1101]01-5: [0]+240'
"""
extraBits = self.extraBits(index)
extraString = '[{:0{}b}]'.format(extra, extraBits)
return '{0}: [{1[0]}]{1[1]:+d}'.format(
self.mnemonic(index, True).replace('x'*(extraBits or 1), extraString),
self.value(index, extra))
#Classes for doing actual work------------------------------------------
class ContextModeKeeper:
"""For computing the literal context mode.
You feed it characters, and it computes indices in the context map.
"""
def __init__(self, mode):
self.chars = deque([0,0], maxlen=2)
self.mode = mode
def setContextMode(self, mode):
"""Switch to given context mode (0..3)"""
self.mode = mode
def getIndex(self):
if self.mode==0: #LSB6
return self.chars[1]&0x3f
elif self.mode==1: #MSB6
return self.chars[1]>>2
elif self.mode==2: #UTF8: character class of previous and a bit of the second
p2,p1 = self.chars
return self.lut0[p1]|self.lut1[p2]
elif self.mode==3: #Signed: initial bits of last two bytes
p2,p1 = self.chars
return self.lut2[p1]<<3|self.lut2[p2]
def add(self, index):
"""Adjust the context for output char (as int)."""
self.chars.append(index)
#0: control #16: quote #32: ,:; #48: AEIOU
#4: tab/lf/cr #20: % #36: . #52: BC..Z
#8: space #24: (<[{ #40: = #56: aeiou
#12:!#$&*+-/?@| #28: )>]} #44: 0-9 #60: bc..z
lut0 = [0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 0, 4, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
8, 12, 16, 12, 12, 20, 12, 16, 24, 28, 12, 12, 32, 12, 36, 12,
44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 32, 32, 24, 40, 28, 12,
12, 48, 52, 52, 52, 48, 52, 52, 52, 48, 52, 52, 52, 52, 52, 48,
52, 52, 52, 52, 52, 48, 52, 52, 52, 52, 52, 24, 12, 28, 12, 12,
12, 56, 60, 60, 60, 56, 60, 60, 60, 56, 60, 60, 60, 60, 60, 56,
60, 60, 60, 60, 60, 56, 60, 60, 60, 60, 60, 24, 12, 28, 12, 0
]+[0,1]*32+[2,3]*32
#0: space 1:punctuation 2:digit/upper 3:lower
lut1 = [ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1,
1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1,
1, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, 0
]+[0]*96+[2]*32
#initial bits: 8*0, 4*0, 2*0, 1*0, 1*1, 2*1, 4*1, 8*1
lut2 = [0]+[1]*15+[2]*48+[3]*64+[4]*64+[5]*48+[6]*15+[7]
assert len(lut0)==len(lut1)==len(lut2)==256
class WordList:
"""Word list.
>>> WordList().word(7, 35555)
b'Program to '
"""
NDBITS = [0, 0, 0, 0, 10, 10, 11, 11, 10, 10,
10, 10, 10, 9, 9, 8, 7, 7, 8, 7,
7, 6, 6, 5, 5]
def __init__(self):
self.file = open('dict', 'rb')
self.compileActions()
def word(self, size, dist):
"""Get word
"""
#split dist in index and action
ndbits = self.NDBITS[size]
index = dist&(1<<ndbits)-1
action = dist>>ndbits
#compute position in file
position = sum(n<<self.NDBITS[n] for n in range(4,size))+size*index
self.file.seek(position)
return self.doAction(self.file.read(size), action)
def upperCase1(self, word):
word = word.decode('utf8')
word = word[0].upper()+word[1:]
return word.encode('utf8')
#Super compact form of action table.
#_ means space, .U means UpperCaseAll, U(w) means UpperCaseFirst
actionTable = r"""
0:w 25:w+_for_ 50:w+\n\t 75:w+. This_100:w+ize_
1:w+_ 26:w[3:] 51:w+: 76:w+, 101:w.U+.
2:_+w+_ 27:w[:-2] 52:_+w+._ 77:.+w+_ 102:\xc2\xa0+w
3:w[1:] 28:w+_a_ 53:w+ed_ 78:U(w)+( 103:_+w+,
4:U(w)+_ 29:w+_that_ 54:w[9:] 79:U(w)+. 104:U(w)+="
5:w+_the_ 30:_+U(w) 55:w[7:] 80:w+_not_ 105:w.U+="
6:_+w 31:w+._ 56:w[:-6] 81:_+w+=" 106:w+ous_
7:s_+w+_ 32:.+w 57:w+( 82:w+er_ 107:w.U+,_
8:w+_of_ 33:_+w+,_ 58:U(w)+,_ 83:_+w.U+_ 108:U(w)+=\'
9:U(w) 34:w[4:] 59:w[:-8] 84:w+al_ 109:_+U(w)+,
10:w+_and_ 35:w+_with_ 60:w+_at_ 85:_+w.U 110:_+w.U+="
11:w[2:] 36:w+\' 61:w+ly_ 86:w+=\' 111:_+w.U+,_
12:w[:-1] 37:w+_from_ 62:_the_+w+_of_ 87:w.U+" 112:_+w.U+,
13:,_+w+_ 38:w+_by_ 63:w[:-5] 88:U(w)+._ 113:w.U+(
14:w+,_ 39:w[5:] 64:w[:-9] 89:_+w+( 114:w.U+._
15:_+U(w)+_ 40:w[6:] 65:_+U(w)+,_ 90:w+ful_ 115:_+w.U+.
16:w+_in_ 41:_the_+w 66:U(w)+" 91:_+U(w)+._116:w.U+=\'
17:w+_to_ 42:w[:-4] 67:.+w+( 92:w+ive_ 117:_+w.U+._
18:e_+w+_ 43:w+. The_ 68:w.U+_ 93:w+less_ 118:_+U(w)+="
19:w+" 44:w.U 69:U(w)+"> 94:w.U+\' 119:_+w.U+=\'
20:w+. 45:w+_on_ 70:w+=" 95:w+est_ 120:_+U(w)+=\'
21:w+"> 46:w+_as_ 71:_+w+. 96:_+U(w)+.
22:w+\n 47:w+_is_ 72:.com/+w 97:w.U+">
23:w[:-3] 48:w[:-7] 98:_+w+=\'
24:w+] 49:w[:-1]+ing_ 74:U(w)+\' 99:U(w)+,
"""
def compileActions(self):
"""Build the action table from the text above
"""
import re
self.actionList = actions = [None]*121
#Action 73, which is too long, looks like this when expanded:
actions[73] = "b' the '+w+b' of the '"
#find out what the columns are
actionLines = self.actionTable.splitlines()
colonPositions = [m.start()
for m in re.finditer(':',actionLines[1])
]+[100]
columns = [(colonPositions[i]-3,colonPositions[i+1]-3)
for i in range(len(colonPositions)-1)]
for line in self.actionTable.splitlines(keepends=False):
for start,end in columns:
action = line[start:end]
#skip empty actions
if not action or action.isspace(): continue
#chop it up, and check if the colon is properly placed
index, colon, action = action[:3], action[3], action[4:]
assert colon==':'
#remove filler spaces at right
action = action.rstrip()
#replace space symbols
action = action.replace('_', ' ')
wPos = action.index('w')
#add quotes around left string when present
#translation: any pattern from beginning, up to
#(but not including) a + following by a w later on
action = re.sub(r"^(.*)(?=\+[U(]*w)", r"b'\1'", action)
#add quotes around right string when present
#translation: anything with a w in it, followed by a +
#and a pattern up to the end
#(there is no variable lookbehind assertion,
#so we have to copy the pattern)
action = re.sub(r"(w[[:\-1\]).U]*)\+(.*)$", r"\1+b'\2'", action)
#expand shortcut for uppercaseAll
action = action.replace(".U", ".upper()")
#store action
actions[int(index)] = action
def doAction(self, w, action):
"""Perform the proper action
"""
#set environment for the UpperCaseFirst
U = self.upperCase1
return eval(self.actionList[action], locals())
class Layout:
"""Class to layout the output.
"""
#display width of hexdata+bitdata
width = 25
#general
def __init__(self, stream):
self.stream = stream
self.bitPtr = self.width
def makeHexData(self, pos):
"""Produce hex dump of all data containing the bits
from pos to stream.pos
"""
firstAddress = pos+7>>3
lastAddress = self.stream.pos+7>>3
return ''.join(map('{:02x} '.format,
self.stream.data[firstAddress:lastAddress]))
def formatBitData(self, pos, width1, width2=0):
"""Show formatted bit data:
Bytes are separated by commas
whole bytes are displayed in hex
>>> Layout(olleke).formatBitData(6, 2, 16)
'|00h|2Eh,|00'
>>> Layout(olleke).formatBitData(4, 1, 0)
'1'
"""
result = []
#make empty prefix code explicit
if width1==0: result = ['()', ',']
for width in width1, width2:
#skip empty width2
if width==0: continue
#build result backwards in a list
while width>0:
availableBits = 8-(pos&7)
if width<availableBits:
#read partial byte, beginning nor ending at boundary
data = self.stream.data[pos>>3] >> (pos&7) & (1<<width)-1
result.append('{:0{}b}'.format(data, width))
elif availableBits<8:
#read rest of byte, ending at boundary
data = self.stream.data[pos>>3] >> (pos&7)
result.append('|{:0{}b}'.format(data, availableBits))
else:
#read whole byte (in hex), beginning and ending at boundary
data = self.stream.data[pos>>3]
result.append('|{:02X}h'.format(data))
width -= availableBits
pos += availableBits
#if width overshot from the availableBits subtraction, fix it
pos += width
#add comma to separate fields
result.append(',')
#concatenate pieces, reversed, skipping the last space
return ''.join(result[-2::-1])
def readPrefixCode(self, alphabet):
"""give alphabet the prefix code that is read from the stream
Called for the following alphabets, in this order:
The alphabet in question must have a "logical" order,
otherwise the assignment of symbols doesn't work.
"""
mode, numberOfSymbols = self.verboseRead(PrefixCodeHeader(alphabet.name))
if mode=='Complex':
#for a complex code, numberOfSymbols means hskip
self.readComplexCode(numberOfSymbols, alphabet)
return alphabet
else:
table = []
#Set table of lengths for mnemonic function
lengths = [[0], [1,1], [1,2,2], '????'][numberOfSymbols-1]
#adjust mnemonic function of alphabet class
def myMnemonic(index):
return '{} bit{}: {}'.format(
lengths[i],
'' if lengths[i]==1 else 's',
alphabet.__class__.mnemonic(alphabet, index)
)
alphabet.mnemonic = myMnemonic
for i in range(numberOfSymbols):
table.append(self.verboseRead(alphabet, skipExtra=True).index)
#restore mnemonic
del alphabet.mnemonic
if numberOfSymbols==4:
#read tree shape to redefine lengths
lengths = self.verboseRead(TreeShapeAlhabet())
#construct the alphabet prefix code
alphabet.setLength(dict(zip(table, lengths)))
return alphabet
def readComplexCode(self, hskip, alphabet):
"""Read complex code"""
stream = self.stream
#read the lengths for the length code
lengths = [1,2,3,4,0,5,17,6,16,7,8,9,10,11,12,13,14,15][hskip:]
codeLengths = {}
total = 0
lol = LengthOfLengthAlphabet('##'+alphabet.name)
#lengthCode will be used for coding the lengths of the new code
#we use it for display until now; definition comes below
lengthCode = LengthAlphabet('#'+alphabet.name)
lengthIter = iter(lengths)
lengthsLeft = len(lengths)
while total<32 and lengthsLeft>0:
lengthsLeft -= 1
newSymbol = next(lengthIter)
lol.description = str(lengthCode[newSymbol])
length = self.verboseRead(lol)
if length:
codeLengths[newSymbol] = length
total += 32>>length
if total>32: raise ValueError("Stream format")
if len(codeLengths)==1: codeLengths[list(codeLengths.keys())[0]] = 0
#Now set the encoding of the lengthCode
lengthCode.setLength(codeLengths)
print("***** Lengths for {} will be coded as:".format(alphabet.name))
lengthCode.showCode()
#Now determine the symbol lengths with the lengthCode
symbolLengths = {}
total = 0
lastLength = 8
alphabetIter = iter(alphabet)
while total<32768:
#look ahead to see what is going to happen
length = lengthCode.decodePeek(
self.stream.peek(lengthCode.maxLength))[1].index
#in every branch, set lengthCode.description to explanatory text
#lengthCode calls format(symbol, extra) with this string
if length==0:
symbol = next(alphabetIter)
lengthCode.description = 'symbol {} unused'.format(symbol)
self.verboseRead(lengthCode)
#unused symbol
continue
if length==16:
lengthCode.description = \
'{1}+3 symbols of length '+str(lastLength)
extra = self.verboseRead(lengthCode)
#scan series of 16s (repeat counts)
#start with repeat count 2
repeat = 2
startSymbol = next(alphabetIter)
endSymbol = next(alphabetIter)
symbolLengths[startSymbol.index] = \
symbolLengths[endSymbol.index] = lastLength
#count the two just defined symbols
total += 2*32768>>lastLength
#note: loop may end because we're there
#even if a 16 _appears_ to follow
while True:
#determine last symbol
oldRepeat = repeat
repeat = (repeat-2<<2)+extra+3
#read as many symbols as repeat increased
for i in range(oldRepeat, repeat):
endSymbol = next(alphabetIter)
symbolLengths[endSymbol.index] = lastLength
#compute new total; it may be end of loop
total += (repeat-oldRepeat)*32768>>lastLength
if total>=32768: break
#see if there is more to do
length = lengthCode.decodePeek(
self.stream.peek(lengthCode.maxLength))[1].index
if length!=16: break
lengthCode.description = 'total {}+{{1}} symbols'.format(
(repeat-2<<2)+3)
extra = self.verboseRead(lengthCode)
elif length==17:
#read, and show explanation
lengthCode.description = '{1}+3 unused'
extra = self.verboseRead(lengthCode)
#scan series of 17s (groups of zero counts)
#start with repeat count 2
repeat = 2
startSymbol = next(alphabetIter)
endSymbol = next(alphabetIter)
#note: loop will not end with total==32768,
#since total doesn't change here
while True:
#determine last symbol
oldRepeat = repeat
repeat = (repeat-2<<3)+extra+3
#read as many symbols as repeat increases
for i in range(repeat-oldRepeat):
endSymbol = next(alphabetIter)
#see if there is more to do
length = lengthCode.decodePeek(
self.stream.peek(lengthCode.maxLength))[1].index
if length!=17: break
lengthCode.description = 'total {}+{{1}} unused'.format(
(repeat-2<<3)+3)
extra = self.verboseRead(lengthCode)
else:
symbol = next(alphabetIter)
#double braces for format
char = str(symbol)
if char in '{}': char *= 2
lengthCode.description = \
'Length for {} is {{0.index}} bits'.format(char)
#output is not needed (will be 0)
self.verboseRead(lengthCode)
symbolLengths[symbol.index] = length
total += 32768>>length
lastLength = length
assert total==32768
alphabet.setLength(symbolLengths)
print('End of table. Prefix code '+alphabet.name+':')
alphabet.showCode()
#stream
def processStream(self):
"""Process a brotli stream.
"""
print('addr hex{:{}s}binary context explanation'.format(
'', self.width-10))
print('Stream header'.center(60, '-'))
self.windowSize = self.verboseRead(WindowSizeAlphabet())
print('Metablock header'.center(60, '='))
self.ISLAST = False
self.output = bytearray()
while not self.ISLAST:
self.ISLAST = self.verboseRead(
BoolCode('LAST', description="Last block"))
if self.ISLAST:
if self.verboseRead(
BoolCode('EMPTY', description="Empty block")): break
if self.metablockLength(): continue
if not self.ISLAST and self.uncompressed(): continue
print('Block type descriptors'.center(60, '-'))
self.numberOfBlockTypes = {}
self.currentBlockCounts = {}
self.blockTypeCodes = {}
self.blockCountCodes = {}
for blockType in (L,I,D): self.blockType(blockType)
print('Distance code parameters'.center(60, '-'))
self.NPOSTFIX, self.NDIRECT = self.verboseRead(DistanceParamAlphabet())
self.readLiteralContextModes()
print('Context maps'.center(60, '-'))
self.cmaps = {}
#keep the number of each kind of prefix tree for the last loop
numberOfTrees = {I: self.numberOfBlockTypes[I]}
for blockType in (L,D):
numberOfTrees[blockType] = self.contextMap(blockType)
print('Prefix code lists'.center(60, '-'))
self.prefixCodes = {}
for blockType in (L,I,D):
self.readPrefixArray(blockType, numberOfTrees[blockType])
self.metablock()
#metablock header
def verboseRead(self, alphabet, context='', skipExtra=False):
"""Read symbol and extra from stream and explain what happens.
Returns the value of the symbol
>>> olleke.pos = 0
>>> l = Layout(olleke)
>>> l.verboseRead(WindowSizeAlphabet())
0000 1b 1011 WSIZE windowsize=(1<<22)-16=4194288
4194288
"""
#TODO 2: verbosity level, e.g. show only codes and maps in header
stream = self.stream
pos = stream.pos
if skipExtra:
length, symbol = alphabet.readTuple(stream)
extraBits, extra = 0, None
else:
length, symbol, extraBits, extra = alphabet.readTupleAndExtra(
stream)
#fields: address, hex data, binary data, name of alphabet, explanation
hexdata = self.makeHexData(pos)
addressField = '{:04x}'.format(pos+7>>3) if hexdata else ''
bitdata = self.formatBitData(pos, length, extraBits)
#bitPtr moves bitdata so that the bytes are easier to read
#jump back to right if a new byte starts
if '|' in bitdata[1:]:
#start over on the right side
self.bitPtr = self.width
fillWidth = self.bitPtr-(len(hexdata)+len(bitdata))
if fillWidth<0: fillWidth = 0
print('{:<5s} {:<{}s} {:7s} {}'.format(
addressField,
hexdata+' '*fillWidth+bitdata, self.width,
context+alphabet.name,
symbol if skipExtra else symbol.explanation(extra),
))
#jump to the right if we started with a '|'
#because we didn't jump before printing
if bitdata.startswith('|'): self.bitPtr = self.width
else: self.bitPtr -= len(bitdata)
return symbol if skipExtra else symbol.value(extra)
def metablockLength(self):
"""Read MNIBBLES and meta block length;
if empty block, skip block and return true.
"""
self.MLEN = self.verboseRead(MetablockLengthAlphabet())
if self.MLEN:
return False
#empty block; skip and return False
self.verboseRead(ReservedAlphabet())
MSKIP = self.verboseRead(SkipLengthAlphabet())
self.verboseRead(FillerAlphabet(streamPos=self.stream.pos))
self.stream.pos += 8*MSKIP
print("Skipping to {:x}".format(self.stream.pos>>3))
return True
def uncompressed(self):
"""If true, handle uncompressed data
"""
ISUNCOMPRESSED = self.verboseRead(
BoolCode('UNCMPR', description='Is uncompressed?'))
if ISUNCOMPRESSED:
self.verboseRead(FillerAlphabet(streamPos=self.stream.pos))
print('Uncompressed data:')
self.output += self.stream.readBytes(self.MLEN)
print(outputFormatter(self.output[-self.MLEN:]))
return ISUNCOMPRESSED
def blockType(self, kind):
"""Read block type switch descriptor for given kind of blockType."""
NBLTYPES = self.verboseRead(TypeCountAlphabet(
'BT#'+kind[0].upper(),
description='{} block types'.format(kind),
))
self.numberOfBlockTypes[kind] = NBLTYPES
if NBLTYPES>=2:
self.blockTypeCodes[kind] = self.readPrefixCode(
BlockTypeAlphabet('BT'+kind[0].upper(), NBLTYPES))
self.blockCountCodes[kind] = self.readPrefixCode(
BlockCountAlphabet('BC'+kind[0].upper()))
blockCount = self.verboseRead(self.blockCountCodes[kind])
else:
blockCount = 1<<24
self.currentBlockCounts[kind] = blockCount
def readLiteralContextModes(self):
"""Read literal context modes.
LSB6: lower 6 bits of last char
MSB6: upper 6 bits of last char
UTF8: rougly dependent on categories:
upper 4 bits depend on category of last char:
control/whitespace/space/ punctuation/quote/%/open/close/
comma/period/=/digits/ VOWEL/CONSONANT/vowel/consonant
lower 2 bits depend on category of 2nd last char:
space/punctuation/digit or upper/lowercase
signed: hamming weight of last 2 chars
"""
print('Context modes'.center(60, '-'))
self.literalContextModes = []
for i in range(self.numberOfBlockTypes[L]):
self.literalContextModes.append(
self.verboseRead(LiteralContextMode(number=i)))
def contextMap(self, kind):
"""Read context maps
Returns the number of differnt values on the context map
(In other words, the number of prefix trees)
"""
NTREES = self.verboseRead(TypeCountAlphabet(
kind[0].upper()+'T#',
description='{} prefix trees'.format(kind)))
mapSize = {L:64, D:4}[kind]
if NTREES<2:
self.cmaps[kind] = [0]*mapSize
else:
#read CMAPkind
RLEMAX = self.verboseRead(RLEmaxAlphabet(
'RLE#'+kind[0].upper(),
description=kind+' context map'))
alphabet = TreeAlphabet('CM'+kind[0].upper(), NTREES=NTREES, RLEMAX=RLEMAX)
cmapCode = self.readPrefixCode(alphabet)
tableSize = mapSize*self.numberOfBlockTypes[kind]
cmap = []
while len(cmap)<tableSize:
cmapCode.description = 'map {}, entry {}'.format(
*divmod(len(cmap), mapSize))
count, value = self.verboseRead(cmapCode)
cmap.extend([value]*count)
assert len(cmap)==tableSize
IMTF = self.verboseRead(BoolCode('IMTF', description='Apply inverse MTF'))
if IMTF:
self.IMTF(cmap)
if kind==L:
print('Context maps for literal data:')
for i in range(0, len(cmap), 64):
print(*(
''.join(map(str, cmap[j:j+8]))
for j in range(i, i+64, 8)
))
else:
print('Context map for distances:')
print(*(
''.join(map('{:x}'.format, cmap[i:i+4]))
for i in range(0, len(cmap), 4)
))
self.cmaps[kind] = cmap
return NTREES
@staticmethod
def IMTF(v):
"""In place inverse move to front transform.
"""
#mtf is initialized virtually with range(infinity)
mtf = []
for i, vi in enumerate(v):
#get old value from mtf. If never seen, take virtual value
try: value = mtf.pop(vi)
except IndexError: value = vi
#put value at front
mtf.insert(0, value)
#replace transformed value
v[i] = value
def readPrefixArray(self, kind, numberOfTrees):
"""Read prefix code array"""
prefixes = []
for i in range(numberOfTrees):
if kind==L: alphabet = LiteralAlphabet(i)
elif kind==I: alphabet = InsertAndCopyAlphabet(i)
elif kind==D: alphabet = DistanceAlphabet(
i, NPOSTFIX=self.NPOSTFIX, NDIRECT=self.NDIRECT)
self.readPrefixCode(alphabet)
prefixes.append(alphabet)
self.prefixCodes[kind] = prefixes
#metablock data
def metablock(self):
"""Process the data.
Relevant variables of self:
numberOfBlockTypes[kind]: number of block types
currentBlockTypes[kind]: current block types (=0)
literalContextModes: the context modes for the literal block types
currentBlockCounts[kind]: counters for block types
blockTypeCodes[kind]: code for block type
blockCountCodes[kind]: code for block count
cmaps[kind]: the context maps (not for I)
prefixCodes[kind][#]: the prefix codes
lastDistances: the last four distances
lastChars: the last two chars
output: the result
"""
print('Meta block contents'.center(60, '='))
self.currentBlockTypes = {L:0, I:0, D:0, pL:1, pI:1, pD:1}
self.lastDistances = deque([17,16,11,4], maxlen=4)
#the current context mode is for block type 0
self.contextMode = ContextModeKeeper(self.literalContextModes[0])
wordList = WordList()
#setup distance callback function
def distanceCallback(symbol, extra):
"callback function for displaying decoded distance"
index, offset = symbol.value(extra)
if index:
#recent distance
distance = self.lastDistances[-index]+offset
return 'Distance: {}last{:+d}={}'.format(index, offset, distance)
#absolute value
if offset<=maxDistance:
return 'Absolute value: {} (pos {})'.format(offset, maxDistance-offset)
#word list value
action, word = divmod(offset-maxDistance, 1<<wordList.NDBITS[copyLen])
return '{}-{} gives word {},{} action {}'.format(
offset, maxDistance, copyLen, word, action)
for dpc in self.prefixCodes[D]: dpc.callback = distanceCallback
blockLen = 0
#there we go
while blockLen<self.MLEN:
#get insert&copy command
litLen, copyLen, dist0Flag = self.verboseRead(
self.prefixCodes[I][
self.figureBlockType(I)])
#literal data
for i in range(litLen):
bt = self.figureBlockType(L)
cm = self.contextMode.getIndex()
ct = self.cmaps[L][bt<<6|cm]
char = self.verboseRead(
self.prefixCodes[L][ct],
context='{},{}='.format(bt,cm))
self.contextMode.add(char)
self.output.append(char)
blockLen += litLen
#check if we're done
if blockLen>=self.MLEN: return
#distance
#distances are computed relative to output length, at most window size
maxDistance = min(len(self.output), self.windowSize)
if dist0Flag:
distance = self.lastDistances[-1]
else:
bt = self.figureBlockType(D)
cm = {2:0, 3:1, 4:2}.get(copyLen, 3)
ct = self.cmaps[D][bt<<2|cm]
index, offset = self.verboseRead(
self.prefixCodes[D][ct],
context='{},{}='.format(bt,cm))
distance = self.lastDistances[-index]+offset if index else offset
if index==1 and offset==0:
#to make sure distance is not put in last distance list
dist0Flag = True
if distance<=maxDistance:
#copy from output
for i in range(
maxDistance-distance,
maxDistance-distance+copyLen):
self.output.append(self.output[i])
if not dist0Flag: self.lastDistances.append(distance)
comment = 'Seen before'
else:
#fetch from wordlist
newWord = wordList.word(copyLen, distance-maxDistance-1)
self.output.extend(newWord)
#adjust copyLen to reflect actual new data
copyLen = len(newWord)
comment = 'From wordlist'
blockLen += copyLen
print(' '*40,
comment,
': "',
outputFormatter(self.output[-copyLen:]),
'"',
sep='')
self.contextMode.add(self.output[-2])
self.contextMode.add(self.output[-1])
def figureBlockType(self, kind):
counts, types = self.currentBlockCounts, self.currentBlockTypes
if counts[kind]==0:
newType = self.verboseRead(self.blockTypeCodes[kind])
if newType==-2: newType = types['P'+kind]
elif newType==-1:
newType = (types[kind]+1)%self.numberOfBlockTypes[kind]
types['P'+kind] = types[kind]
types[kind] = newType
counts[kind] = self.verboseRead(self.blockCountCodes[kind])
counts[kind] -=1
return types[kind]
__test__ = {
'BitStream': """
>>> bs = BitStream(b'Jurjen')
>>> bs.readBytes(2)
b'Ju'
>>> bs.read(6) #r=01110010
50
>>> bs
BitStream(pos=2:6)
>>> bs.peek(5) #j=01101010
9
>>> bs.readBytes(2)
Traceback (most recent call last):
...
ValueError: readBytes: need byte boundary
""",
'Symbol': """
>>> a=Symbol(MetablockLengthAlphabet(),5)
>>> len(a)
2
>>> int(a)
5
>>> a.bitPattern()
'01'
>>> a.value(200000)
200001
>>> a.explanation(300000)
'data length: 493e0h+1=300001'
""",
'RangeDecoder': """
>>> a=RangeDecoder(bitLength=3)
>>> len(a)
8
>>> a.name='t'
>>> list(a)
[Symbol(t, 0), Symbol(t, 1), Symbol(t, 2), Symbol(t, 3), Symbol(t, 4), Symbol(t, 5), Symbol(t, 6), Symbol(t, 7)]
>>> a[2]
Symbol(t, 2)
>>> a.bitPattern(4)
'100'
>>> a.length(2)
3
>>> a.decodePeek(15)
(3, Symbol(t, 7))
>>>
""",
'PrefixDecoder': """
>>> a=PrefixDecoder(decodeTable={0:1,1:2,3:3,7:4})
>>> len(a)
4
>>> a.name='t'
>>> list(a)
[Symbol(t, 1), Symbol(t, 2), Symbol(t, 3), Symbol(t, 4)]
>>> a.decodePeek(22)
(1, Symbol(t, 1))
>>> a.decodePeek(27)
(3, Symbol(t, 3))
>>> a.length(1)
1
>>> a.length(4)
3
""",
'Code': """
>>> a=Code('t',alphabetSize=10)
>>> len(a)
10
>>> a.showCode()
0000:0 0001:1 0010:2 0011:3 0100:4 0101:5 0110:6 0111:7 1000:8 1001:9
>>> a.setLength({2:1,3:2,5:3,6:3})
>>> a.showCode()
0:2 01:3 011:5 111:6
>>> len(a)
4
>>> def callback(i): return 'call{}back'.format(i)
>>> a=Code('t',callback=callback,bitLength=3)
>>> a[6].explanation()
'call6back'
""",
'WithExtra': """
>>> class A(WithExtra):
... extraTable = [0,1,1,2,2]
>>> a=A('t',alphabetSize=5)
>>> a[1]
Symbol(t, 1)
>>> a.extraBits(2)
1
>>> a.mnemonic(4)
'4'
>>> a.readTupleAndExtra(BitStream(b'\x5b'))
(3, Symbol(t, 3), 2, 3)
""",
'BoolCode': """
>>> BoolCode('test')[0].explanation()
'0: False'
""",
'Enumerator': """
>>> class A(Enumerator):
... extraTable = [0,1,1,2,2]
... value0=3
>>> a=A(alphabetLength=5)
>>> a.value(3)
Traceback (most recent call last):
...
TypeError: value() missing 1 required positional argument: 'extra'
>>> a.explanation(3,4)
'xx 011: 8-11; 8+4=12'
""",
'WindowSizeAlphabet': """
>>> windowSizeAlphabet = WindowSizeAlphabet()
>>> windowSizeAlphabet[0]
Traceback (most recent call last):
...
ValueError: No symbol WindowSizeAlphabet[0]
>>> len(windowSizeAlphabet)
16
>>> windowSizeAlphabet[21]
Symbol(WSIZE, 21)
>>> windowSizeAlphabet[21].bitPattern()
'1001'
>>> windowSizeAlphabet[21].extraBits()
0
>>> windowSizeAlphabet[21].index
21
>>> windowSizeAlphabet[10].value()
1008
>>> windowSizeAlphabet[10].explanation()
'windowsize=(1<<10)-16=1008'
>>> windowSizeAlphabet.showCode()
0:65520 1100001:16368 1110001:32752 0011:262128
0000001:131056 0010001:None 1001:2097136 1011:4194288
1000001:4080 1010001:8176 0101:524272 0111:1048560
0100001:1008 0110001:2032 1101:8388592 1111:16777200
""",
'TypeCountAlphabet': """
>>> typeCountAlphabet = TypeCountAlphabet(description='bananas')
>>> len(typeCountAlphabet)
9
>>> typeCountAlphabet[3]
Symbol(BT#, 3)
>>> typeCountAlphabet[9]
Traceback (most recent call last):
...
ValueError: No symbol TypeCountAlphabet[9]
>>> print(typeCountAlphabet[3])
xx,0101
>>> typeCountAlphabet[8].value(127)
256
>>> typeCountAlphabet[4].explanation(2)
'xxx,0111: 11 bananas'
>>> typeCountAlphabet[0].explanation()
'0: 1 banana'
""",
'DistanceParamAlphabet': """
>>> dpa = DistanceParamAlphabet()
>>> dpa.showCode()
00:PF0 01:PF1 10:PF2 11:PF3
>>> dpa.readTupleAndExtra(BitStream(b'\\x29'))
(2, Symbol(DIST, 1), 4, 10)
>>> dpa.explanation(2, 5)
'2 postfix bits and 0101<<2=20 direct codes'
""",
'LiteralAlphabet': """
>>> LiteralAlphabet(-1).showCode() #doctest: +ELLIPSIS
00000000:\\x00 00110100:4 01101000:h 10011100:\\x9c 11010000:\\xd0
00000001:\\x01 00110101:5 01101001:i 10011101:\\x9d 11010001:\\xd1
00000010:\\x02 00110110:6 01101010:j 10011110:\\x9e 11010010:\\xd2
...
00101111:/ 01100011:c 10010111:\\x97 11001011:\\xcb 11111111:\\xff
00110000:0 01100100:d 10011000:\\x98 11001100:\\xcc
00110001:1 01100101:e 10011001:\\x99 11001101:\\xcd
00110010:2 01100110:f 10011010:\\x9a 11001110:\\xce
00110011:3 01100111:g 10011011:\\x9b 11001111:\\xcf
""",
'BlockCountAlphabet': """
>>> bc=BlockCountAlphabet('BCL')
>>> len(bc)
26
>>> bs=BitStream(b'\\x40\\x83\\xc8\\x59\\12\\x02')
>>> x = bc.readTupleAndExtra(bs); x[1].explanation(x[3])
'Block count: xx 00000: 1-4; 1+2=3'
>>> x = bc.readTupleAndExtra(bs); x[1].explanation(x[3])
'Block count: xxx 00110: 33-40; 33+0=33'
>>> x = bc.readTupleAndExtra(bs); x[1].explanation(x[3])
'Block count: xxxxxx 10001: 305-368; 305+28=333'
>>> x = bc.readTupleAndExtra(bs); x[1].explanation(x[3])
'Block count: xxxxxxxxxxx 10110: 2289-4336; 2289+1044=3333'
""",
'Layout': """
>>> olleke.pos = 0
>>> l = Layout(olleke)
>>> l.verboseRead(WindowSizeAlphabet())
0000 1b 1011 WSIZE windowsize=(1<<22)-16=4194288
4194288
>>> l.verboseRead(BoolCode('LAST', description="Last block"))
1 LAST Last block: 1: True
True
>>> l.verboseRead(BoolCode('EMPTY', description="Empty block"))
0 EMPTY Empty block: 0: False
False
>>> l.verboseRead(MetablockLengthAlphabet())
0001 2e 00 |00h|2Eh,|00 MLEN data length: 002eh+1=47
47
>>> olleke.pos = 76
>>> l = Layout(olleke)
>>> x = l.verboseRead(DistanceAlphabet(0,NPOSTFIX=0,NDIRECT=0), skipExtra=True)
000a 82 10|1100 D0 10[15*x]-3
>>> x.explanation(0x86a3)
'10[1000011010100011]-3: [0]+100000'
""",
'olleke': """
>>> olleke.pos = 0
>>> try: Layout(olleke).processStream()
... except NotImplementedError: pass
... #doctest: +REPORT_NDIFF
addr hex binary context explanation
-----------------------Stream header------------------------
0000 1b 1011 WSIZE windowsize=(1<<22)-16=4194288
======================Metablock header======================
1 LAST Last block: 1: True
0 EMPTY Empty block: 0: False
0001 2e 00 |00h|2Eh,|00 MLEN data length: 002eh+1=47
-------------------Block type descriptors-------------------
0003 00 0 BT#L 0: 1 literal block type
0 BT#I 0: 1 insert&copy block type
0 BT#D 0: 1 distance block type
------------------Distance code parameters------------------
0004 44 0|000,00 DIST 0 postfix bits and 0000<<0=0 direct codes
-----------------------Context modes------------------------
10 LC0 Context mode for type 0: 2(UTF8)
------------------------Context maps------------------------
0 LT# 0: 1 literal prefix tree
0 DT# 0: 1 distance prefix tree
---------------------Prefix code lists----------------------
10 PFX L0 is complex with lengths 3,4,0,5,17...
0005 4f 1|0 ##L0 len 3: coded with 3 bits
0111 ##L0 len 4: coded with 1 bits
10 ##L0 unused: coded with 3 bits
0006 d6 0|0 ##L0 len 5: skipped
011 ##L0 zero xxx: coded with 2 bits
***** Lengths for L0 will be coded as:
0:len 4 01:zero xxx 011:unused 111:len 3
0007 95 1|11,01 #L0 7+3 unused
0 #L0 Length for \\n is 4 bits
001,01 #L0 1+3 unused
0008 44 010,0|1 #L0 total 19+2 unused
0 #L0 Length for " " is 4 bits
0 #L0 Length for ! is 4 bits
0009 cb 011,|01 #L0 3+3 unused
|110,01 #L0 total 35+6 unused
000a 82 0 #L0 Length for K is 4 bits
000,01 #L0 0+3 unused
0 #L0 Length for O is 4 bits
000b 4d 01|1 #L0 symbol P unused
011 #L0 symbol Q unused
0 #L0 Length for R is 4 bits
000c 88 000,|01 #L0 0+3 unused
|100,01 #L0 total 11+4 unused
000d b6 0 #L0 Length for b is 4 bits
011 #L0 symbol c unused
011 #L0 symbol d unused
000e 27 11|1 #L0 Length for e is 3 bits
010,01 #L0 2+3 unused
|0 #L0 Length for k is 4 bits
000f 1f 111 #L0 Length for l is 3 bits
011 #L0 symbol m unused
0 #L0 Length for n is 4 bits
|0 #L0 Length for o is 4 bits
0010 c1 000,01 #L0 0+3 unused
0 #L0 Length for s is 4 bits
0011 b4 0|11 #L0 symbol t unused
0 #L0 Length for u is 4 bits
End of table. Prefix code L0:
000:e 0010:\\n 0110:! 0001:O 0101:b 0011:n 0111:s
100:l 1010:" " 1110:K 1001:R 1101:k 1011:o 1111:u
11,01 PFX IC0 is simple with 4 code words
0012 2a |2Ah|10 IC0 ? bits: I5C4
0013 b5 ec 00|B5h IC0 ? bits: I6+xC7
0015 22 0010|111011 IC0 ? bits: I8+xC5
0016 8c 001100|0010 IC0 ? bits: I0C14+xx
0 SHAPE False: lengths 2,2,2,2
0017 74 10,0|1 PFX D0 is simple with 3 code words
0018 a6 0|01110 D0 1 bit: 2last-3
010011 D0 2 bits: 11xx-3
0019 aa 01010|1 D0 2 bits: 11xxx-3
====================Meta block contents=====================
|1,01 IC0 Literal: 9, copy: 5
001a 41 0001 0,0=L0 O
100 0,48=L0 l
001b a2 10|0 0,62=L0 l
000 0,63=L0 e
001c a1 1|101 0,59=L0 k
000 0,63=L0 e
|1010 0,59=L0 " "
001d b5 0101 0,11=L0 b
|1011 0,60=L0 o
001e 24 0 0,3=D0 Distance: 2last-3=8
Seen before: "lleke"
0,10 IC0 Literal: 6, copy: 7
|0010 0,59=L0 \\n
001f 89 1001 0,7=L0 R
000 0,52=L0 e
0020 fa 010|1 0,58=L0 b
1111 0,63=L0 u
0021 eb 011|1 0,59=L0 s
11,01 0,3=D0 Absolute value: 12 (pos 8)
Seen before: "olleke\\n"
0022 db 01,1|1 IC0 Literal: 0, copy: 15
|110,11 0,3=D0 Absolute value: 27 (pos 0)
Seen before: "Olleke bolleke\\n"
0023 f8 00 IC0 Literal: 5, copy: 4
1110 0,7=L0 K
0024 2c 00|11 0,52=L0 n
1011 0,62=L0 o
0025 0d 1|00 0,59=L0 l
0110 0,63=L0 !
""",
'file': """
>>> try: Layout(BitStream(
... open("H:/Downloads/brotli-master/tests/testdata/10x10y.compressed",'rb')
... .read())).processStream()
... except NotImplementedError: pass
addr hex binary context explanation
-----------------------Stream header------------------------
0000 1b 1011 WSIZE windowsize=(1<<22)-16=4194288
======================Metablock header======================
1 LAST Last block: 1: True
0 EMPTY Empty block: 0: False
0001 13 00 |00h|13h,|00 MLEN data length: 0013h+1=20
-------------------Block type descriptors-------------------
0003 00 0 BT#L 0: 1 literal block type
0 BT#I 0: 1 insert&copy block type
0 BT#D 0: 1 distance block type
------------------Distance code parameters------------------
0004 a4 0|000,00 DIST 0 postfix bits and 0000<<0=0 direct codes
-----------------------Context modes------------------------
10 LC0 Context mode for type 0: 2(UTF8)
------------------------Context maps------------------------
0 LT# 0: 1 literal prefix tree
0 DT# 0: 1 distance prefix tree
---------------------Prefix code lists----------------------
0005 b0 0|1,01 PFX L0 is simple with 2 code words
0006 b2 0|1011000 L0 1 bit: X
0007 ea 0|1011001 L0 1 bit: Y
01,01 PFX IC0 is simple with 2 code words
0008 81 0000001|111 IC0 1 bit: I1C9&D=0
0009 47 02 0|47h|1 IC0 1 bit: I1C9
00,01 PFX D0 is simple with 1 code word
000b 8a 010|000 D0 0 bits: 10x-3
====================Meta block contents=====================
1 IC0 Literal: 1, copy: 9
0 0,0=L0 X
0,() 0,3=D0 Absolute value: 1 (pos 0)
Seen before: "XXXXXXXXX"
0 IC0 Literal: 1, copy: 9, same distance
|1 0,54=L0 Y
Seen before: "YYYYYYYYY"
""",
'XY': """
>>> try: Layout(BitStream(brotli.compress('X'*10+'Y'*10))).processStream()
... except NotImplementedError: pass
addr hex binary context explanation
-----------------------Stream header------------------------
0000 1b 1011 WSIZE windowsize=(1<<22)-16=4194288
======================Metablock header======================
1 LAST Last block: 1: True
0 EMPTY Empty block: 0: False
0001 13 00 |00h|13h,|00 MLEN data length: 0013h+1=20
-------------------Block type descriptors-------------------
0003 00 0 BT#L 0: 1 literal block type
0 BT#I 0: 1 insert&copy block type
0 BT#D 0: 1 distance block type
------------------Distance code parameters------------------
0004 a4 0|000,00 DIST 0 postfix bits and 0000<<0=0 direct codes
-----------------------Context modes------------------------
10 LC0 Context mode for type 0: 2(UTF8)
------------------------Context maps------------------------
0 LT# 0: 1 literal prefix tree
0 DT# 0: 1 distance prefix tree
---------------------Prefix code lists----------------------
0005 b0 0|1,01 PFX L0 is simple with 2 code words
0006 b2 0|1011000 L0 1 bit: X
0007 82 0|1011001 L0 1 bit: Y
00,01 PFX IC0 is simple with 1 code word
0008 84 0000100|100 IC0 0 bits: I4C6&D=0
0009 00 00,0|1 PFX D0 is simple with 1 code word
000a e0 0|00000 D0 0 bits: last
====================Meta block contents=====================
() IC0 Literal: 4, copy: 6, same distance
0 0,0=L0 X
0 0,52=L0 X
0 0,54=L0 X
0 0,54=L0 X
Seen before: "XXXXXX"
() IC0 Literal: 4, copy: 6, same distance
1 0,54=L0 Y
1 0,54=L0 Y
|1 0,54=L0 Y
000b 01 1 0,54=L0 Y
Seen before: "YYYYYY"
""",
'empty': """
>>> try: Layout(BitStream(b'\\x81\\x16\\x00\\x58')).processStream()
... except NotImplementedError: pass
addr hex binary context explanation
-----------------------Stream header------------------------
0000 81 0000001 WSIZE windowsize=(1<<17)-16=131056
======================Metablock header======================
|1 LAST Last block: 1: True
0001 16 0 EMPTY Empty block: 0: False
11 MLEN 11: empty block
0 RSVD Reserved (must be zero)
0002 00 000000|00,01 SKIP skip length: 0h+1=1
|00 SKIP 2 bits ignored
Skipping to 4
""",
}
if __name__=='__main__':
import sys
if len(sys.argv)>1:
l = Layout(BitStream(open(sys.argv[1],'rb').read()))
l.processStream()
else:
sys.path.append("h:/Persoonlijk/bin")
try:
import brotli
open('brotlidump.br', 'wb').write(
brotli.compress(
open('brotlidump.py', 'r').read()
))
olleke = BitStream(brotli.compress(
'Olleke bolleke\nRebusolleke\nOlleke bolleke\nKnol!'))
except ImportError: pass
import doctest
doctest.testmod(optionflags=doctest.REPORT_NDIFF
#|doctest.FAIL_FAST
)
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