def writeU8(os, u8):
    os.write(bytes((u8&0xff,)))

def writeU16(os, u16):
    os.write(bytes(((u16>>8)&0xff,)))
    os.write(bytes((u16&0xff,)))

def writeU32(os, u32):
    os.write(bytes(((u32>>24)&0xff,)))
    os.write(bytes(((u32>>16)&0xff,)))
    os.write(bytes(((u32>>8)&0xff,)))
    os.write(bytes((u32&0xff,)))

def writeString(os, s):
    b = bytes(s, "utf-8")
    writeU16(os, len(b))
    os.write(b)

def writeLongString(os, s):
    b = bytes(s, "utf-8")
    writeU32(os, len(b))
    os.write(b)

def bytesToInt(b):
    s = 0
    for x in b:
        s = (s<<8)+x
    return s