bigint: Add modulus bit length to Modulus.

src/arithmetic/bigint.rs

@@ -45,7 +45,7 @@ use super::n0::N0;
 pub(crate) use super::nonnegative::Nonnegative;
 use crate::{
     arithmetic::montgomery::*,
-    bits, c, cpu, error,
+    c, cpu, error,
     limb::{self, Limb, LimbMask, LIMB_BITS},
     polyfill::u64_from_usize,
 };
@@ -305,8 +305,8 @@ impl<M> One<M, RR> {
     // values, using `LIMB_BITS` here, rather than `N0::LIMBS_USED * LIMB_BITS`,
     // is correct because R**2 will still be a multiple of the latter as
     // `N0::LIMBS_USED` is either one or two.
-    fn newRR(m: &Modulus<M>, m_bits: bits::BitLength) -> Self {
-        let m_bits = m_bits.as_usize_bits();
+    fn newRR(m: &Modulus<M>) -> Self {
+        let m_bits = m.len_bits().as_usize_bits();
         let r = (m_bits + (LIMB_BITS - 1)) / LIMB_BITS * LIMB_BITS;
 
         // base = 2**(lg m - 1).

src/arithmetic/bigint/modulus.rs

@@ -179,11 +179,12 @@ impl<M> OwnedModulusWithOne<M> {
             let partial = Modulus {
                 limbs: &n,
                 n0: n0.clone(),
+                len_bits,
                 m: PhantomData,
                 cpu_features,
             };
 
-            One::newRR(&partial, len_bits)
+            One::newRR(&partial)
         };
 
         Ok(Self {
@@ -214,6 +215,7 @@ impl<M> OwnedModulusWithOne<M> {
         Modulus {
             limbs: &self.limbs,
             n0: self.n0.clone(),
+            len_bits: self.len_bits,
             m: PhantomData,
             cpu_features: self.cpu_features,
         }
@@ -233,6 +235,7 @@ impl<M: PublicModulus> OwnedModulusWithOne<M> {
 pub struct Modulus<'a, M> {
     limbs: &'a [Limb],
     n0: N0,
+    len_bits: BitLength,
     m: PhantomData<M>,
     cpu_features: cpu::Features,
 }
@@ -263,6 +266,10 @@ impl<M> Modulus<'_, M> {
         &self.n0
     }
 
+    pub fn len_bits(&self) -> BitLength {
+        self.len_bits
+    }
+
     #[inline]
     pub(crate) fn cpu_features(&self) -> cpu::Features {
         self.cpu_features