Exemple #1
0
    def readBits(self, address, nbits, endian):
        assert endian in (BIG_ENDIAN, LITTLE_ENDIAN)

        shift, data, missing = self.read(address, nbits)
        if missing:
            raise ReadStreamError(nbits, address)
        value = str2long(data, endian)
        if endian is BIG_ENDIAN:
            value >>= len(data) * 8 - shift - nbits
        else:
            value >>= shift
        return value & (1 << nbits) - 1
Exemple #2
0
    def readBits(self, address, nbits, endian):
        assert endian in (BIG_ENDIAN, LITTLE_ENDIAN, MIDDLE_ENDIAN)

        if endian is MIDDLE_ENDIAN:
            # read an aligned chunk of words
            wordaddr, remainder = divmod(address, 16)
            wordnbits = alignValue(remainder+nbits, 16)
            _, data, missing = self.read(wordaddr*16, wordnbits)
            shift = remainder
        else:
            shift, data, missing = self.read(address, nbits)
        if missing:
            raise ReadStreamError(nbits, address)
        value = str2long(data, endian)
        if endian in (BIG_ENDIAN, MIDDLE_ENDIAN):
            value >>= len(data) * 8 - shift - nbits
        else:
            value >>= shift
        return value & (1 << nbits) - 1
    def readBits(self, address, nbits, endian):
        assert endian in (BIG_ENDIAN, LITTLE_ENDIAN, MIDDLE_ENDIAN)

        if endian is MIDDLE_ENDIAN:
            # read an aligned chunk of words
            wordaddr, remainder = divmod(address, 16)
            wordnbits = alignValue(remainder + nbits, 16)
            _, data, missing = self.read(wordaddr * 16, wordnbits)
            shift = remainder
        else:
            shift, data, missing = self.read(address, nbits)
        if missing:
            raise ReadStreamError(nbits, address)
        value = str2long(data, endian)
        if endian in (BIG_ENDIAN, MIDDLE_ENDIAN):
            value >>= len(data) * 8 - shift - nbits
        else:
            value >>= shift
        return value & (1 << nbits) - 1
Exemple #4
0
def fixPNG(data):
    # array -> str
    data = data.tostring()

    origdata = data
    datalen = len(data)
    data = StringIO(data)

    data.seek(0)
    data.write("\x89PNG\r\n\x1a\n")

    index = 8
    while index < (datalen-4):
        data.seek(index)
        size = str2long(data.read(4), BIG_ENDIAN)
        chunksize = size+12
        if datalen < (index+chunksize):
            info("fixPNG: Skip invalid chunk at %s" % index)
            break
        crcofs = index+chunksize-4
        data.seek(crcofs)
        oldcrc = data.read(4)

        data.seek(index+4)
        o = data.tell()
        crcdata = data.read(chunksize-8)
        newcrc = long2raw(pngCRC32(crcdata), BIG_ENDIAN, 4)

        data.seek(index+chunksize-4)
        data.write(newcrc)

        index += chunksize

    data.seek(0,0)
    data = data.read()
    assert len(data) == len(origdata)

    # str -> array
    data = array('B', data)
    return data