Struct Condition 

pub struct Condition<T>(/* private fields */)
where
    MaskType<T>: SupportedMaskType;

Helper functions for checking some condition on some data using constant-time operations.

Implementations

impl Condition<i64>

pub const TRUE: Self

TRUE is the bit vector of all 1’s

pub const FALSE: Self

FALSE is the bit vector of all 0’s

pub const fn from_bool<const VALUE: bool>() -> Self

pub const fn from_bool_var(value: bool) -> Self

pub const fn is_bit_set(value: i64, bit: i64) -> Self

pub const fn is_negative(value: i64) -> Self

pub const fn is_not_zero(value: i64) -> Self

pub const fn is_zero(value: i64) -> Self

pub const fn is_equal(x: i64, y: i64) -> Self

pub const fn is_lt(x: i64, y: i64) -> Self

pub fn is_lte(x: i64, y: i64) -> Self

pub const fn is_gt(x: i64, y: i64) -> Self

pub fn is_gte(x: i64, y: i64) -> Self

pub fn is_within_range(value: i64, min: i64, max: i64) -> Self

pub fn is_in_list(value: i64, list: &[i64]) -> Self

pub fn mov(self, src: i64, dst: &mut i64)

Conditionally move the source value to the destination if the condition is true, otherwise nothing is moved.

pub const fn negate(self, value: i64) -> i64

Conditionally negate the value.

negate(-1) gives -3

value is -1 (i.e., all bits are 1, ...1111)

Condition self.0 is 1 (...0001) (assuming TRUE)

XOR operation was executed as value ^ self.0

Then ...1111 XOR ...0001 = ...1110 (i.e., -2)

Subtraction operation is wrapping_sub(self.0)

Then -2 - 1 = -3

As a result, 1, which is the negation of -1, should be returned, but -3 is output.

Therefore, if the Self::TRUE constant value of the i64 Condition implementation is changed to -1, the test also runs normally.

pub const fn or_halves(value: i64) -> i64

pub const fn select(self, true_value: i64, false_value: i64) -> i64

Conditional selection: return true_value if the condition is true, otherwise return false_value.

pub const fn swap(self, lhs: i64, rhs: i64) -> (i64, i64)

Conditional swap: returns (lhs, rhs) if the condition is true, otherwise returns (rhs, lhs).

pub const fn to_bool_var(self) -> bool

impl Condition<u64>

pub const TRUE: Self

TRUE is the bit vector of all 1’s

pub const FALSE: Self

FALSE is the bit vector of all 0’s

pub const fn from_bool<const VALUE: bool>() -> Self

this is the core logic for constant-time mask generation for unsigned integers Unlike signed integers where we can rely on Two’s Complement via negation -(v as i64), for u64 we must use wrapping subtraction to achieve the all-ones bit pattern (u64::MAX) for true

pub fn select(self, a: u64, b: u64) -> u64

impl the select function manually for u64 although a fully generic impl<T> would be the ultimate long-term goal

pub fn is_true(&self) -> bool

Trait Implementations

impl<T> BitAnd for Condition<T>

where MaskType<T>: SupportedMaskType, T: BitAnd<T, Output = T>,

type Output = Condition<T>

The resulting type after applying the & operator.

fn bitand(self, rhs: Self) -> Self

Performs the & operation.

impl<T> BitAndAssign for Condition<T>

where MaskType<T>: SupportedMaskType, T: BitAndAssign<T>,

fn bitand_assign(&mut self, rhs: Self)

Performs the &= operation.

impl<T> BitOr for Condition<T>

where MaskType<T>: SupportedMaskType, T: BitOr<T, Output = T>,

type Output = Condition<T>

The resulting type after applying the | operator.

fn bitor(self, rhs: Self) -> Self

Performs the | operation.

impl<T> BitOrAssign for Condition<T>

where MaskType<T>: SupportedMaskType, T: BitOrAssign<T>,

fn bitor_assign(&mut self, rhs: Self)

Performs the |= operation.

impl<T> BitXor for Condition<T>

where MaskType<T>: SupportedMaskType, T: BitXor<T, Output = T>,

type Output = Condition<T>

The resulting type after applying the ^ operator.

fn bitxor(self, rhs: Self) -> Self

Performs the ^ operation.

impl<T> BitXorAssign for Condition<T>

where MaskType<T>: SupportedMaskType, T: BitXorAssign<T>,

fn bitxor_assign(&mut self, rhs: Self)

Performs the ^= operation.

impl<T: Clone> Clone for Condition<T>

where MaskType<T>: SupportedMaskType,

fn clone(&self) -> Condition<T>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> Not for Condition<T>

where MaskType<T>: SupportedMaskType, T: Not<Output = T>,

type Output = Condition<T>

The resulting type after applying the ! operator.

fn not(self) -> Self

Performs the unary ! operation.

impl<T: Copy> Copy for Condition<T>

where MaskType<T>: SupportedMaskType,