// Bounded searches over sorted f32 buffers (32 halvings: any buffer a
// kernel can bind).

// The last index k in 0..n with buf[k] <= x, or -1 when buf[0] > x.
fn last_le(buf, n, x) {
    let lo: int = 0
    let hi: int = n
    for it in 0..32 {
        if lo < hi {
            let mid = (lo + hi) / 2
            if buf[mid] <= x { lo = mid + 1 } else { hi = mid }
        }
    }
    lo - 1
}

// The first index k in 0..n with buf[k] > x, or n.
fn first_gt(buf, n, x) { last_le(buf, n, x) + 1 }