Use wrapping subs instead of saturating subs

Author: fjarri

src/uint/boxed/div.rs

@@ -489,7 +489,7 @@ pub(crate) fn div_rem_vartime_in_place(x: &mut [Limb], y: &mut [Limb]) {
                 (x[xi + i + 1 - yc], carry) =
                     x[xi + i + 1 - yc].adc(Limb::select(Limb::ZERO, y[i], ct_borrow), carry);
             }
-            ct_borrow.select_word(quo, quo.saturating_sub(1))
+            ct_borrow.select_word(quo, quo.wrapping_sub(1))
         };
 
         // Store the quotient within dividend and set x_hi to the current highest word

src/uint/div.rs

@@ -260,7 +260,7 @@ impl<const LIMBS: usize> Uint<LIMBS> {
                         x[xi + i + 1 - yc].adc(Limb::select(Limb::ZERO, y[i], ct_borrow), carry);
                     i += 1;
                 }
-                ct_borrow.select_word(quo, quo.saturating_sub(1))
+                ct_borrow.select_word(quo, quo.wrapping_sub(1))
             };
 
             // Store the quotient within dividend and set x_hi to the current highest word

src/uint/div_limb.rs

@@ -178,7 +178,7 @@ pub(crate) const fn div3by2(
         // If r < b and q*y[-2] > r*x[-1], then set q = q - 1 and r = r + v1
         let done = ConstChoice::from_word_nonzero((rem >> Word::BITS) as Word)
             .or(ConstChoice::from_wide_word_le(qy, rx));
-        quo = done.select_word(quo.saturating_sub(1), quo);
+        quo = done.select_word(quo.wrapping_sub(1), quo);
         rem = done.select_wide_word(rem + (v1_reciprocal.divisor_normalized as WideWord), rem);
         i += 1;
     }