SEAD RNG - RainMz/NintendoClients GitHub Wiki

SEAD is Nintendo's private standard library. It is used by various first party games and the Pia library uses it as well.

Its random number generator works as follows:

class Random:
    def __init__(self, seed):
        multiplier = 0x6C078965
        
        temp = seed
        self.state = []
        for i in range(1, 5):
            temp ^= temp >> 30
            temp = (temp * multiplier + i) & 0xFFFFFFFF
            self.state.append(temp)
    
    # Returns a random 32-bit integer
    def u32(self):
        temp = self.state[0]
        temp = (temp ^ (temp << 11)) & 0xFFFFFFFF
        temp ^= temp >> 8
        temp ^= self.state[3]
        temp ^= self.state[3] >> 19
        self.state[0] = self.state[1]
        self.state[1] = self.state[2]
        self.state[2] = self.state[3]
        self.state[3] = temp
        return temp
    
    # Returns a random integer smaller than 'max'
    def uint(self, max):
        return (self.u32() * max) >> 32

The random number generator is used by ENL to generate the game-specific key for the LAN protocol and by Pia to generate the session key in LDN mode.