rtl addition chain

addchain_5inv_rtl.py

#                                                                                                                                               ---> up to here is a multiple of 3 :-)
x_p = 0b11001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001101001110100111101110000011001001101000010000101001100000111000101110000011110000111100111111000011001100110011001100110011001101

pchain = Chain()
pi = pa = 1
for i in range(1, 114):
    pi = pchain.sqr(pi)
    if '101110000011001001101000010000101001100000111000101110000011110000111100111111000011001100110011001100110011001101'[113-i] == '1':
        pa = pchain.mul(pa, pi)

b = '1000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100011010001101'
assert int(b, 2)*3 == 0b11001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001101001110100111
pj = pchain.sqrmul(pi, 1, pi)
for j in range(1, 140):
    pj = pchain.sqr(pj)
    if b[139-j] == '1':
        pa = pchain.mul(pa, pj)

assert pa == x_p, "\n" + format(pa, '0255b') + "\n" + format(x_p, '0255b')
print(pchain)