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AK: Add FixedPoint cast operator for up/downcasting to other sizes

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This enables casting between different size FixedPoint variables or
constructing them from other sized FixedPoint values.
This commit is contained in:
Tom 2022-01-20 21:31:13 -07:00 committed by Linus Groh
parent 06fc72ca0c
commit c468a9cc2d
2 changed files with 61 additions and 0 deletions
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29
AK/FixedPoint.h
View file

@ -20,6 +20,9 @@ class FixedPoint {
using This = FixedPoint<precision, Underlying>;
constexpr static Underlying radix_mask = (static_cast<Underlying>(1) << precision) - 1;
template<size_t P, typename U>
friend class FixedPoint;
public:
constexpr FixedPoint() = default;
template<Integral I>
@ -34,6 +37,12 @@ public:
{
}
template<size_t P, typename U>
explicit constexpr FixedPoint(FixedPoint<P, U> const& other)
: m_value(other.template cast_to<precision, Underlying>().m_value)
{
}
template<FloatingPoint F>
explicit ALWAYS_INLINE operator F() const
{
@ -304,7 +313,27 @@ public:
template<FloatingPoint F>
bool operator<=(F other) const { return *this <= (This)other; }
template<size_t P, typename U>
operator FixedPoint<P, U>() const
{
return cast_to<P, U>();
}
private:
template<size_t P, typename U>
constexpr FixedPoint<P, U> cast_to() const
{
U raw_value = static_cast<U>(m_value >> precision) << P;
if constexpr (precision > P)
raw_value |= (m_value & radix_mask) >> (precision - P);
else if constexpr (precision < P)
raw_value |= static_cast<U>(m_value & radix_mask) << (P - precision);
else
raw_value |= m_value & radix_mask;
return FixedPoint<P, U>::create_raw(raw_value);
}
static This create_raw(Underlying value)
{
This t {};

32
Tests/AK/TestFixedPoint.cpp
View file

@ -73,6 +73,38 @@ TEST_CASE(rounding)
EXPECT_EQ(Type(-1.5).ltrunk(), -1);
}
TEST_CASE(cast)
{
FixedPoint<16, u32> downcast_value1(FixedPoint<32, u64>(123.4567));
EXPECT((double)downcast_value1 >= 123.4566 && (double)downcast_value1 <= 123.4568);
static constexpr FixedPoint<32, u64> value1(321.7654);
downcast_value1 = value1;
EXPECT((double)downcast_value1 >= 321.7653 && (double)downcast_value1 <= 321.7655);
FixedPoint<6, u32> downcast_value2(FixedPoint<32, u64>(4567.123456));
EXPECT((double)downcast_value2 >= 4567.1 && (double)downcast_value2 <= 4567.2);
downcast_value2 = FixedPoint<32, u64>(7654.654321);
EXPECT((double)downcast_value2 >= 7654.64 && (double)downcast_value2 <= 7654.66);
EXPECT((double)downcast_value2 >= 7654.64 && (double)downcast_value2 <= 7654.66);
FixedPoint<6, u32> downcast_value3(FixedPoint<32, u64>(4567.987654));
EXPECT((double)downcast_value3 >= 4567.9 && (double)downcast_value3 <= 4567.99);
downcast_value3 = FixedPoint<32, u64>(7654.456789);
EXPECT((double)downcast_value3 >= 7654.45 && (double)downcast_value3 <= 7654.46);
FixedPoint<32, u64> upcast_value1(FixedPoint<16, u32>(123.4567));
EXPECT((double)upcast_value1 >= 123.4566 && (double)upcast_value1 <= 123.4568);
upcast_value1 = FixedPoint<16, u32>(321.7654);
EXPECT((double)upcast_value1 >= 321.7653 && (double)upcast_value1 <= 321.7655);
FixedPoint<32, u64> upcast_value2(FixedPoint<6, u32>(4567.123456));
EXPECT((double)upcast_value2 >= 4567.1 && (double)upcast_value2 <= 4567.2);
upcast_value2 = FixedPoint<6, u32>(7654.654321);
EXPECT((double)upcast_value2 >= 7654.64 && (double)upcast_value2 <= 7654.66);
FixedPoint<32, u64> upcast_value3(FixedPoint<6, u32>(4567.987654));
EXPECT((double)upcast_value3 >= 4567.9 && (double)upcast_value3 <= 4567.99);
upcast_value3 = FixedPoint<6, u32>(7654.456789);
EXPECT((double)upcast_value3 >= 7654.45 && (double)upcast_value3 <= 7654.46);
}
TEST_CASE(formatter)
{
EXPECT_EQ(String::formatted("{}", FixedPoint<16>(123.456)), "123.455993"sv);