80 lines
2.2 KiB
Rust
80 lines
2.2 KiB
Rust
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//! Macro definitions which are a part of the public API.
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/// Internal implementation detail of [`const_assert_eq`] and [`const_assert_ne`].
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#[doc(hidden)]
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#[macro_export]
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macro_rules! const_assert_n {
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($n:expr, $($arg:tt)*) => {{
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// TODO(tarcieri): gensym a name so it's unique per invocation of the macro?
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mod __const_assert {
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pub(super) struct Assert<const N: usize>;
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impl<const N: usize> Assert<N> {
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pub(super) const ASSERT: () = assert!($($arg)*);
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}
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}
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__const_assert::Assert::<$n>::ASSERT
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}};
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}
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/// Const-friendly assertion that two values are equal.
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///
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/// ```
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/// const _: () = crypto_bigint::const_assert_eq!(0, 0, "zero equals zero");
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/// ```
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#[macro_export]
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macro_rules! const_assert_eq {
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($left:expr, $right:expr $(,)?) => (
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$crate::const_assert_n!($left, $left == $right)
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);
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($left:expr, $right:expr, $($arg:tt)+) => (
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$crate::const_assert_n!($left, $left == $right, $($arg)+)
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);
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}
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/// Const-friendly assertion that two values are NOT equal.
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///
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/// ```
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/// const _: () = crypto_bigint::const_assert_ne!(0, 1, "zero is NOT equal to one");
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/// ```
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#[macro_export]
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macro_rules! const_assert_ne {
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($left:expr, $right:expr $(,)?) => (
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$crate::const_assert_n!($left, $left != $right)
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);
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($left:expr, $right:expr, $($arg:tt)+) => (
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$crate::const_assert_n!($left, $left != $right, $($arg)+)
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);
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}
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/// Calculate the number of limbs required to represent the given number of bits.
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// TODO(tarcieri): replace with `generic_const_exprs` (rust-lang/rust#76560) when stable
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#[macro_export]
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macro_rules! nlimbs {
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($bits:expr) => {
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$bits / $crate::Limb::BITS
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};
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}
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#[cfg(test)]
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mod tests {
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#[cfg(target_pointer_width = "32")]
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#[test]
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fn nlimbs_for_bits_macro() {
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assert_eq!(nlimbs!(64), 2);
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assert_eq!(nlimbs!(128), 4);
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assert_eq!(nlimbs!(192), 6);
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assert_eq!(nlimbs!(256), 8);
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}
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#[cfg(target_pointer_width = "64")]
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#[test]
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fn nlimbs_for_bits_macro() {
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assert_eq!(nlimbs!(64), 1);
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assert_eq!(nlimbs!(128), 2);
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assert_eq!(nlimbs!(192), 3);
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assert_eq!(nlimbs!(256), 4);
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}
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}
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