small refactor

ff/src/fields/fft_friendly.rs

@@ -56,15 +56,15 @@ pub trait FftField: crate::Field {
 
             omega = large_subgroup_root_of_unity;
             for _ in q_adicity..small_subgroup_base_adicity {
-                omega = omega.pow([q as u64]);
+                omega = omega.pow([q]);
             }
 
             for _ in two_adicity..Self::TWO_ADICITY {
                 omega.square_in_place();
             }
         } else {
             // Compute the next power of 2.
-            let size = n.next_power_of_two() as u64;
+            let size = n.next_power_of_two();
             let log_size_of_group = ark_std::log2(usize::try_from(size).expect("too large"));
 
             if n != size || log_size_of_group > Self::TWO_ADICITY {

poly/src/domain/radix2/fft.rs

@@ -88,17 +88,15 @@ impl<F: FftField> Radix2EvaluationDomain<F> {
     }
 
     fn fft_helper_in_place<T: DomainCoeff<F>>(&self, x_s: &mut [T], ord: FFTOrder) {
-        use FFTOrder::*;
-
         let log_len = ark_std::log2(x_s.len());
 
-        if ord == OI {
+        if ord == FFTOrder::OI {
             self.oi_helper(x_s, self.group_gen, 1);
         } else {
             self.io_helper(x_s, self.group_gen);
         }
 
-        if ord == II {
+        if ord == FFTOrder::II {
             derange(x_s, log_len);
         }
     }
@@ -107,15 +105,13 @@ impl<F: FftField> Radix2EvaluationDomain<F> {
     // The results here must all be divided by |x_s|,
     // which is left up to the caller to do.
     fn ifft_helper_in_place<T: DomainCoeff<F>>(&self, x_s: &mut [T], ord: FFTOrder) {
-        use FFTOrder::*;
-
         let log_len = ark_std::log2(x_s.len());
 
-        if ord == II {
+        if ord == FFTOrder::II {
             derange(x_s, log_len);
         }
 
-        if ord == IO {
+        if ord == FFTOrder::IO {
             self.io_helper(x_s, self.group_gen_inv);
         } else {
             self.oi_helper(x_s, self.group_gen_inv, 1);