# Part of the Fifteen-Thieves Project
# Chris Xiong 2020
# License: Expat (MIT)

def roland_checksum(payload):
    return (0x80 - sum(payload) % 0x80) % 0x80

def check_roland_checksum(msg):
    return (0x80 - sum(msg[6:-2]) % 0x80) % 0x80 == msg[-2]

def int2belist(x):
    ret = []
    while x > 0:
        ret = [x & 0xff] + ret
        x >>= 8
    return ret

def belist2int(x):
    ret = 0
    for i in x:
        ret <<= 8
        ret |= i
    return ret

def int2b7belist(x):
    ret = []
    while x > 0:
        ret = [x & 0x7f] + ret
        x >>= 7
    return ret

def strb7list(x):
    return ' '.join([format(a, "02x") for a in x])

def b7belist2int(x):
    ret = 0
    for i in x:
        ret <<= 7
        ret |= i
    return ret

def hexrep2b7val(x):
    ret = 0
    b = 0
    while x > 0:
        if x & 0xff > 0x7f:
            raise ValueError("invalid value")
        ret |= (x & 0xff) << (7 * b)
        b += 1
        x >>= 8
    return ret

def padbelist(x, l=4):
    return ([0]*(l-len(x))) + x

def int2packetint(x):
    ret = []
    while x > 0:
        ret = [x & 0x0f] + ret
        x >>= 4
    return ret

def packetint2int(x):
    ret = 0
    for i in x:
        ret <<= 4
        ret |= i
    return ret

def load_memoryregion(fn):
    ret = []
    with open(fn, "rb") as f:
        while True:
            addr = list(f.read(4))
            if len(addr) < 4:
                break
            l = belist2int(list(f.read(4)))
            data = list(f.read(l))
            ret.append( (addr, data) )
    return ret

def write_memoryregion(fn, mr):
    with open(fn, "wb") as f:
        for addr, data in mr:
            l = padbelist(int2belist(len(data)))
            f.write(bytearray(addr))
            f.write(bytearray(l))
            f.write(bytearray(data))

# vim: expandtab shiftwidth=4 tabstop=4