BN1 encounter check pseudocode

function encounterCheck() {
    var area = loadByte(0x02000214);
    var subarea = loadByte(0x02000215);

    var steps = loadWord(0x020003F4);
    var prev = loadWord(0x020003F8);

    // If area is an overworld area, fail
    if (area < 0x80) {
        return false;
    }
    area -= 0x80;

    // If steps since last check < 64, fail
    if (steps - prev < 0x40) {
        return false;
    }
    prev = steps;
    storeWord(prev, 0x020003F8);

    // Get the encounter rate curve index associated with this area
    // Lower index = steeper curve = encounter rate rises more quickly
    var curve = loadByte(0x080099BC + area * 0x10 + subarea);

    // Count roughly equals number of encounter checks before this one
    var count = (steps / 0x40);
    // Rate no longer increases after 16 encounter checks
    if (count >= 0x11) {
        count = 0x10;
    }

    // Load the current encounter rate for this check
    var rate = loadByte(0x08009934 + count * 8 + curve);

    if (rand(0x20) >= rate) {
        return false;
    } else {
        return true;
    }
}