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upcast multiply

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This commit is contained in:
Corwin 2023-05-30 22:21:12 +01:00
parent da5aed83e3
commit 9fa8f75202
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1 changed files with 14 additions and 10 deletions
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24
agb-fixnum/src/lib.rs
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@ -79,6 +79,8 @@ pub trait FixedWidthUnsignedInteger:
fn ten() -> Self;
/// Converts an i32 to it's own representation, panics on failure
fn from_as_i32(v: i32) -> Self;
/// Returns (a * b) >> N
fn upcast_multiply(a: Self, b: Self, n: usize) -> Self;
}
/// Trait for an integer that includes negation
@ -89,7 +91,7 @@ pub trait FixedWidthSignedInteger: FixedWidthUnsignedInteger + Neg<Output = Self
}
macro_rules! fixed_width_unsigned_integer_impl {
($T: ty) => {
($T: ty, $Upcast: ty) => {
impl FixedWidthUnsignedInteger for $T {
#[inline(always)]
fn zero() -> Self {
@ -107,6 +109,10 @@ macro_rules! fixed_width_unsigned_integer_impl {
fn from_as_i32(v: i32) -> Self {
v as $T
}
#[inline(always)]
fn upcast_multiply(a: Self, b: Self, n: usize) -> Self {
(((a as $Upcast) * (b as $Upcast)) >> n) as $T
}
}
};
}
@ -122,12 +128,12 @@ macro_rules! fixed_width_signed_integer_impl {
};
}
fixed_width_unsigned_integer_impl!(u8);
fixed_width_unsigned_integer_impl!(i16);
fixed_width_unsigned_integer_impl!(u16);
fixed_width_unsigned_integer_impl!(i32);
fixed_width_unsigned_integer_impl!(u32);
fixed_width_unsigned_integer_impl!(usize);
fixed_width_unsigned_integer_impl!(u8, u32);
fixed_width_unsigned_integer_impl!(i16, i32);
fixed_width_unsigned_integer_impl!(u16, u32);
fixed_width_unsigned_integer_impl!(i32, i64);
fixed_width_unsigned_integer_impl!(u32, u64);
fixed_width_unsigned_integer_impl!(usize, u64);
fixed_width_signed_integer_impl!(i16);
fixed_width_signed_integer_impl!(i32);
@ -204,9 +210,7 @@ where
{
type Output = Self;
fn mul(self, rhs: Num<I, N>) -> Self::Output {
Num(((self.floor() * rhs.floor()) << N)
+ (self.floor() * rhs.frac() + rhs.floor() * self.frac())
+ ((self.frac() * rhs.frac()) >> N))
Num(I::upcast_multiply(self.0, rhs.0, N))
}
}