wide-mul crate feature

fixed_wide/Cargo.toml

@@ -4,8 +4,9 @@ version = "0.1.0"
 edition = "2021"
 
 [features]
-default=["zeroes"]
+default=["zeroes","wide-mul"]
 ratio=[]
+wide-mul=[]
 zeroes=["ratio","dep:arrayvec"]
 
 [dependencies]

fixed_wide/src/fixed.rs

@@ -1,6 +1,7 @@
 use bnum::{BInt,cast::As};
 
 #[derive(Clone,Copy,Debug,Hash)]
+/// A Fixed point number for which multiply operations widen the bits in the output. (when the wide-mul feature is enabled)
 /// N is the number of u64s to use
 /// F is the number of fractional bits (always N*32 lol)
 pub struct Fixed<const N:usize,const F:usize>{
@@ -139,6 +140,10 @@ impl_additive_operator!( Fixed, BitOr, bitor, Self );
 impl_additive_assign_operator!( Fixed, BitXorAssign, bitxor_assign );
 impl_additive_operator!( Fixed, BitXor, bitxor, Self );
 
+// non-wide operators.  The result is the same width as the inputs.
+
+// This macro is not used in the default configuration.
+#[allow(unused_macros)]
 macro_rules! impl_multiplicative_operator_not_const_generic {
 	( ($struct: ident, $trait: ident, $method: ident, $output: ty ), $width:expr ) => {
 		impl<const F:usize> core::ops::$trait for $struct<$width,F>{
@@ -175,6 +180,7 @@ macro_rules! impl_multiply_operator_not_const_generic {
 			}
 			}
 		}
+		#[cfg(not(feature="wide-mul"))]
 		impl_multiplicative_operator_not_const_generic!(($struct, $trait, $method, $output ), $width);
 	}
 }
@@ -191,6 +197,7 @@ macro_rules! impl_divide_operator_not_const_generic {
 			}
 			}
 		}
+		#[cfg(all(not(feature="wide-mul"),not(feature="ratio")))]
 		impl_multiplicative_operator_not_const_generic!(($struct, $trait, $method, $output ), $width);
 	};
 }
@@ -248,6 +255,13 @@ impl_multiplicative_assign_operator!( Fixed, MulAssign, mul_assign );
 impl_multiplicative_operator!( Fixed, Mul, mul, Self );
 impl_multiplicative_assign_operator!( Fixed, DivAssign, div_assign );
 impl_multiplicative_operator!( Fixed, Div, div, Self );
+#[cfg(feature="ratio")]
+impl<const LHS_N:usize,const LHS_F:usize,const RHS_N:usize,const RHS_F:usize> core::ops::Div<Fixed<RHS_N,RHS_F>> for Fixed<LHS_N,LHS_F>{
+	type Output=crate::ratio::Ratio<Fixed<LHS_N,LHS_F>,Fixed<RHS_N,RHS_F>>;
+	fn div(self, other: Fixed<RHS_N,RHS_F>)->Self::Output{
+		crate::ratio::Ratio::new(self,other)
+	}
+}
 
 macro_rules! impl_shift_operator {
 	( $struct: ident, $trait: ident, $method: ident, $output: ty ) => {
@@ -274,6 +288,30 @@ impl_shift_operator!( Fixed, Shl, shl, Self );
 impl_shift_assign_operator!( Fixed, ShrAssign, shr_assign );
 impl_shift_operator!( Fixed, Shr, shr, Self );
 
+// wide operators.  The result width is the sum of the input widths, i.e. none of the multiplication
+
+macro_rules! impl_wide_operators{
+	($lhs:expr,$rhs:expr)=>{
+		impl core::ops::Mul<Fixed<$rhs,{$rhs*32}>> for Fixed<$lhs,{$lhs*32}>{
+			type Output=Fixed<{$lhs+$rhs},{($lhs+$rhs)*32}>;
+			fn mul(self, other: Fixed<$rhs,{$rhs*32}>)->Self::Output{
+				paste::item!{
+				self.[<wide_mul_ $lhs _ $rhs>](other)
+				}
+			}
+		}
+		#[cfg(not(feature="ratio"))]
+		impl core::ops::Div<Fixed<$rhs,{$rhs*32}>> for Fixed<$lhs,{$lhs*32}>{
+			type Output=Fixed<{$lhs+$rhs},{($lhs+$rhs)*32}>;
+			fn div(self, other: Fixed<$rhs,{$rhs*32}>)->Self::Output{
+				paste::item!{
+				self.[<wide_div_ $lhs _ $rhs>](other)
+				}
+			}
+		}
+	}
+}
+
 // WIDE MUL: multiply into a wider type
 // let a = I32F32::ONE;
 // let b:I64F64 = a.wide_mul(a);
@@ -301,6 +339,8 @@ macro_rules! impl_wide_not_const_generic{
 				}
 			}
 		}
+		#[cfg(feature="wide-mul")]
+		impl_wide_operators!($lhs,$rhs);
 	};
 }
 

fixed_wide/src/tests.rs

@@ -65,7 +65,7 @@ fn test_sqrt_zero(){
 #[test]
 fn test_sqrt_low(){
 	let a=I32F32::HALF;
-	let b=a*a;
+	let b=a.fixed_mul(a);
 	assert_eq!(b.sqrt(),a);
 }
 fn find_equiv_sqrt_via_f64(n:I32F32)->I32F32{