From 920d5995c7eb04e8b8174a17a1829ecda4e9188d Mon Sep 17 00:00:00 2001
From: wborgeaud <williamborgeaud@gmail.com>
Date: Mon, 13 Dec 2021 16:46:49 +0100
Subject: [PATCH] Replace `bits()` fn with `BITS` const

---
 src/field/field_types.rs      | 6 +-----
 src/fri/recursive_verifier.rs | 2 +-
 src/gates/base_sum.rs         | 2 +-
 3 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/field/field_types.rs b/src/field/field_types.rs
index a3affc13..b6d9e700 100644
--- a/src/field/field_types.rs
+++ b/src/field/field_types.rs
@@ -59,6 +59,7 @@ pub trait Field:
     /// Generator of a multiplicative subgroup of order `2^TWO_ADICITY`.
     const POWER_OF_TWO_GENERATOR: Self;
 
+    /// The bit length of the field order.
     const BITS: usize;
 
     fn order() -> BigUint;
@@ -407,11 +408,6 @@ pub trait Field:
 pub trait PrimeField: Field<PrimeField = Self> {
     const ORDER: u64;
 
-    /// The number of bits required to encode any field element.
-    fn bits() -> usize {
-        bits_u64(Self::NEG_ONE.to_canonical_u64())
-    }
-
     fn to_canonical_u64(&self) -> u64;
 
     fn to_noncanonical_u64(&self) -> u64;
diff --git a/src/fri/recursive_verifier.rs b/src/fri/recursive_verifier.rs
index c2684725..dc4214b5 100644
--- a/src/fri/recursive_verifier.rs
+++ b/src/fri/recursive_verifier.rs
@@ -338,7 +338,7 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
         // verify that this has a negligible impact on soundness error.
         Self::assert_noncanonical_indices_ok(&common_data.config);
         let x_index = challenger.get_challenge(self);
-        let mut x_index_bits = self.low_bits(x_index, n_log, F::bits());
+        let mut x_index_bits = self.low_bits(x_index, n_log, F::BITS);
 
         let cap_index =
             self.le_sum(x_index_bits[x_index_bits.len() - common_data.config.cap_height..].iter());
diff --git a/src/gates/base_sum.rs b/src/gates/base_sum.rs
index 2ab5345b..7ea235fa 100644
--- a/src/gates/base_sum.rs
+++ b/src/gates/base_sum.rs
@@ -24,7 +24,7 @@ impl<const B: usize> BaseSumGate<B> {
     }
 
     pub fn new_from_config<F: PrimeField>(config: &CircuitConfig) -> Self {
-        let num_limbs = F::bits().min(config.num_routed_wires - Self::START_LIMBS);
+        let num_limbs = F::BITS.min(config.num_routed_wires - Self::START_LIMBS);
         Self::new(num_limbs)
     }