Function flip_msb

ciphercore-base/src/ops/comparisons.rs:331–336

- This function flips all values of the input Array's last component, which correspond to MSB bit (after `pull_out_bits`), to enable the signed comparisons. - Why bit flip is sufficient for obtaining signed comparisons given unsigned comparison functionality? Please see below example: |sign bit MSB| b1| b0| unsigned value| signed value| |------------|----|----|---------------|--------------

(ip: Node)

/// Here we xor the MSB bit with 1 to flip it. It is more efficient than do slice + concat.
/// We rely on broadcasting to avoid the huge constants in graph.
pub(super) fn flip_msb(ip: Node) -> Result<Node> {
    ip.add(get_msb_flip_constant(
        ip.get_type()?.get_shape(),
        &ip.get_graph(),
    )?)
}

fn get_msb_flip_constant(shape: ArrayShape, g: &Graph) -> Result<Node> {
    let n = shape[shape.len() - 1] as usize;