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use crate::ciphertext::RadixCiphertext;
use crate::ServerKey;
impl ServerKey {
/// Computes homomorphically a subtraction of a ciphertext by a scalar.
///
/// # Example
///
/// ```rust
/// use concrete_integer::gen_keys_radix;
/// use concrete_shortint::parameters::PARAM_MESSAGE_2_CARRY_2;
///
/// // We have 4 * 2 = 8 bits of message
/// let size = 4;
/// let (cks, sks) = gen_keys_radix(&PARAM_MESSAGE_2_CARRY_2, size);
///
/// let msg = 165;
/// let scalar = 112;
///
/// let mut ct = cks.encrypt(msg);
///
/// // Compute homomorphically an addition:
/// let ct_res = sks.smart_scalar_sub_parallelized(&mut ct, scalar);
///
/// // Decrypt:
/// let dec = cks.decrypt(&ct_res);
/// assert_eq!(msg - scalar, dec);
/// ```
pub fn smart_scalar_sub_parallelized(
&self,
ct: &mut RadixCiphertext,
scalar: u64,
) -> RadixCiphertext {
if !self.is_scalar_sub_possible(ct, scalar) {
self.full_propagate_parallelized(ct);
}
self.unchecked_scalar_sub(ct, scalar)
}
pub fn smart_scalar_sub_assign_parallelized(&self, ct: &mut RadixCiphertext, scalar: u64) {
if !self.is_scalar_sub_possible(ct, scalar) {
self.full_propagate_parallelized(ct);
}
self.unchecked_scalar_sub_assign(ct, scalar);
}
}