indexAlpha

fn indexAlpha(
    rand: u64,
    lanes: u32,
    segments: u32,
    threads: u24,
    n: u32,
    slice: u32,
    lane: u24,
    index: u32,
) u32

File

Code

fn indexAlpha(
    rand: u64,
    lanes: u32,
    segments: u32,
    threads: u24,
    n: u32,
    slice: u32,
    lane: u24,
    index: u32,
) u32 {
    var ref_lane = @as(u32, @intCast(rand >> 32)) % threads;
    if (n == 0 and slice == 0) {
        ref_lane = lane;
    }
    var m = 3 * segments;
    var s = ((slice + 1) % sync_points) * segments;
    if (lane == ref_lane) {
        m += index;
    }
    if (n == 0) {
        m = slice * segments;
        s = 0;
        if (slice == 0 or lane == ref_lane) {
            m += index;
        }
    }
    if (index == 0 or lane == ref_lane) {
        m -= 1;
    }
    var p = @as(u64, @as(u32, @truncate(rand)));
    p = (p * p) >> 32;
    p = (p * m) >> 32;
    return ref_lane * lanes + @as(u32, @intCast(((s + m - (p + 1)) % lanes)));
}