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https://github.com/italicsjenga/agb.git
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add optimisation for 64 bit upcast multiply (#444)
This is really good now! - [x] Changelog updated / no changelog update needed
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commit
20a7c262e9
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@ -91,7 +91,7 @@ pub trait FixedWidthSignedInteger: FixedWidthUnsignedInteger + Neg<Output = Self
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}
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}
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macro_rules! fixed_width_unsigned_integer_impl {
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macro_rules! fixed_width_unsigned_integer_impl {
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($T: ty, $Upcast: ty) => {
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($T: ty, $Upcast: ident) => {
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impl FixedWidthUnsignedInteger for $T {
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impl FixedWidthUnsignedInteger for $T {
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#[inline(always)]
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#[inline(always)]
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fn zero() -> Self {
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fn zero() -> Self {
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@ -109,11 +109,38 @@ macro_rules! fixed_width_unsigned_integer_impl {
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fn from_as_i32(v: i32) -> Self {
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fn from_as_i32(v: i32) -> Self {
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v as $T
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v as $T
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}
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}
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upcast_multiply_impl!($T, $Upcast);
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}
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};
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}
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macro_rules! upcast_multiply_impl {
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($T: ty, optimised_64_bit) => {
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#[inline(always)]
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fn upcast_multiply(a: Self, b: Self, n: usize) -> Self {
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let mask = (Self::one() << n).wrapping_sub(1);
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let a_floor = a >> n;
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let a_frac = a & mask;
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let b_floor = b >> n;
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let b_frac = b & mask;
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(a_floor.wrapping_mul(b_floor) << n)
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.wrapping_add(
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a_floor
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.wrapping_mul(b_frac)
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.wrapping_add(b_floor.wrapping_mul(a_frac)),
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)
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.wrapping_add(a_frac.wrapping_mul(b_frac) >> n)
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}
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};
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($T: ty, $Upcast: ty) => {
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#[inline(always)]
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#[inline(always)]
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fn upcast_multiply(a: Self, b: Self, n: usize) -> Self {
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fn upcast_multiply(a: Self, b: Self, n: usize) -> Self {
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(((a as $Upcast) * (b as $Upcast)) >> n) as $T
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(((a as $Upcast) * (b as $Upcast)) >> n) as $T
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}
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}
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}
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};
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};
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}
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}
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@ -131,8 +158,9 @@ macro_rules! fixed_width_signed_integer_impl {
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fixed_width_unsigned_integer_impl!(u8, u32);
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fixed_width_unsigned_integer_impl!(u8, u32);
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fixed_width_unsigned_integer_impl!(i16, i32);
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fixed_width_unsigned_integer_impl!(i16, i32);
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fixed_width_unsigned_integer_impl!(u16, u32);
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fixed_width_unsigned_integer_impl!(u16, u32);
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fixed_width_unsigned_integer_impl!(i32, i64);
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fixed_width_unsigned_integer_impl!(u32, u64);
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fixed_width_unsigned_integer_impl!(i32, optimised_64_bit);
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fixed_width_unsigned_integer_impl!(u32, optimised_64_bit);
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fixed_width_signed_integer_impl!(i16);
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fixed_width_signed_integer_impl!(i16);
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fixed_width_signed_integer_impl!(i32);
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fixed_width_signed_integer_impl!(i32);
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@ -1370,4 +1398,17 @@ mod tests {
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]
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]
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);
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);
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}
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}
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#[cfg(not(debug_assertions))]
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#[test]
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fn test_all_multiplies() {
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use super::*;
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for i in 0..u32::MAX {
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let fix_num: Num<_, 7> = Num::from_raw(i);
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let upcasted = ((i as u64 * i as u64) >> 7) as u32;
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assert_eq!((fix_num * fix_num).to_raw(), upcasted);
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}
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}
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}
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}
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