MSCC RNG Notes
----

MSCC uses the standard srand and rand functions from Microsoft's C library.
It is a linear congruential generator with multiplier 214013 and accumulator 2531011.

    uint32_t rngState;

    void srand(uint16_t seed) {
        rngState = seed;
    }

    int rand(void) {
        rngState = (0x343fd*rngState + 0x269ec3);
        return (rngState>>16) & 0x7fff;
    }

The RNG is seeded with the current time at program start.
It is not re-seeded between levels, so the RNG state at the end of one level
carries over to the next.

    srand(GetCurrentTime());

To get random numbers in a certain range, the game uses the following function:

    int RandInt(int n) {
        return rand() % n;
    }


Of course, knowing the RNG algorithm doesn't do you much unless you also know how the 
game uses the random numbers it gets.

MSCC uses randomness in three places: random force floors, walkers, and blobs.
(Also in the ending animation, but that doesn't affect anything important.)

Force floors are the simplest. 

    switch RandInt(4)
        case 0: north
        case 1: south
        case 2: west
        case 3: east
    end

Walkers first try to move straight in the direction they are facing;
if that direction is blocked, they then turn in a random direction
and try that, until one succeeds or they have exhausted all directions.

    try moving straight
    if blocked
        repeat until all directions tried or movement is not blocked
            direction = RandInt(3)
            if direction not already tried 
                switch direction
                    case 0: try moving left of the original direction
                    case 1: try moving right of the original direction
                    case 2: try moving opposite of the original direction
                end
            end
        end
    end

Blobs are basically the same as walkers, except they choose a random direction
to move initially instead of moving straight.
Note: positive x is east, positive y is south.

    repeat until (xdir == 0 and ydir != 0) or (ydir == 0 and xdir != 0)
        xdir = RandInt(3)-1
        ydir = RandInt(3)-1
    end
    try moving that direction
    if blocked
        same as walkers...
    end