Precompute power+exponent for iterative conversion

The maximum power of the base that can fit into a given data type is
constant. There's no point in computing it at runtime, if we can just
store it in a compile-time constants array.

The code isn't the most beautiful, but that's mostly because Rust const
functions are still a bit limited.
One function was duplicated, because it was easy to get a slow version
to compile in const context, and const context doesn't really care...

1 files changed, 3 insertions, 1 deletions

diff --git a/src/passwordmaker/base_conversion/mod.rs b/src/passwordmaker/base_conversion/mod.rs
index dc98c92..bb3fbd6 100644
--- a/src/passwordmaker/base_conversion/mod.rs
+++ b/src/passwordmaker/base_conversion/mod.rs
@@ -3,6 +3,8 @@ use iterative_conversion_impl::PadWithAZero;
 pub(super) use iterative_conversion::IterativeBaseConversion;
 pub(super) use iterative_conversion_impl::{SixteenBytes, ArbitraryBytes};
 
+use self::iterative_conversion::ConstantMaxPotencyCache;
+
 mod iterative_conversion;
 mod iterative_conversion_impl;
 
@@ -14,7 +16,7 @@ pub(super) trait BaseConversion {
 
 impl<T, const N : usize, const M : usize> BaseConversion for T 
     where T : ToArbitraryBytes<Output = ArbitraryBytes<N>>,
-        for<'a> T::Output: From<&'a usize> + From<&'a u32> + PadWithAZero<Output = ArbitraryBytes<M>>,
+        for<'a> T::Output: From<&'a usize> + From<&'a u32> + PadWithAZero<Output = ArbitraryBytes<M>> + ConstantMaxPotencyCache<usize>,
 {
     type Output = IterativeBaseConversion<ArbitraryBytes<N>, usize>;
     fn convert_to_base(self, base : usize) -> Self::Output {