use as_bits_mut to optimize sqrt

lib/fixed_wide/src/fixed.rs

@@ -33,6 +33,14 @@ impl<const N:usize,const F:usize> Fixed<N,F>{
 		self.bits
 	}
 	#[inline]
+	pub const fn as_bits(&self)->&BInt<N>{
+		&self.bits
+	}
+	#[inline]
+	pub const fn as_bits_mut(&mut self)->&mut BInt<N>{
+		&mut self.bits
+	}
+	#[inline]
 	pub const fn raw_digit(value:i64)->Self{
 		let mut digits=[0u64;N];
 		digits[0]=value.abs() as u64;
@@ -788,13 +796,10 @@ macro_rules! impl_not_const_generic{
 				let wide_self=self.[<fix_ $_2n>]();
 				//descend down the bits and check if flipping each bit would push the square over the input value
 				for shift in (0..=max_shift).rev(){
-					let new_result={
-						let mut bits=result.to_bits().to_bits();
-						bits.set_bit(shift,true);
-						Self::from_bits(BInt::from_bits(bits))
-					};
-					if new_result.[<wide_mul_ $n _ $n>](new_result)<=wide_self{
-						result=new_result;
+					result.as_bits_mut().as_bits_mut().set_bit(shift,true);
+					if wide_self<result.[<wide_mul_ $n _ $n>](result){
+						// put it back lol
+						result.as_bits_mut().as_bits_mut().set_bit(shift,false);
 					}
 				}
 				result