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MACAddress: constexpr support

Problem:
- `MACAddress` class is not usable in a compile-time context.
- `__builtin_memcpy` is not constexpr in gcc.

Solution:
- Decorate functions with `constexpr` keyword.
- Use default constructors and destructors.
- Change `__builtin_memcpy` to a hand-written `for` loop and let the
  compiler's optimizer take care of it.
- Add tests to ensure compile-time capabilities.
This commit is contained in:
Lenny Maiorani 2020-11-16 17:10:02 -07:00 committed by Andreas Kling
parent 0e132d345f
commit 964d2e0dd0
2 changed files with 41 additions and 16 deletions

View file

@ -33,12 +33,16 @@
class [[gnu::packed]] MACAddress
{
public:
MACAddress() { }
MACAddress(const u8 data[6])
constexpr MACAddress() = default;
constexpr MACAddress(const u8 data[6])
{
__builtin_memcpy(m_data, data, 6);
for (auto i = 0u; i < sizeof(m_data); ++i) {
m_data[i] = data[i];
}
}
MACAddress(u8 a, u8 b, u8 c, u8 d, u8 e, u8 f)
constexpr MACAddress(u8 a, u8 b, u8 c, u8 d, u8 e, u8 f)
{
m_data[0] = a;
m_data[1] = b;
@ -47,15 +51,16 @@ public:
m_data[4] = e;
m_data[5] = f;
}
~MACAddress() { }
u8 operator[](int i) const
constexpr ~MACAddress() = default;
constexpr u8 operator[](int i) const
{
ASSERT(i >= 0 && i < 6);
return m_data[i];
}
bool operator==(const MACAddress& other) const
constexpr bool operator==(const MACAddress& other) const
{
return !__builtin_memcmp(m_data, other.m_data, sizeof(m_data));
}
@ -65,7 +70,7 @@ public:
return String::formatted("{:02x}:{:02x}:{:02x}:{:02x}:{:02x}:{:02x}", m_data[0], m_data[1], m_data[2], m_data[3], m_data[4], m_data[5]);
}
bool is_zero() const
constexpr bool is_zero() const
{
return m_data[0] == 0 && m_data[1] == 0 && m_data[2] == 0 && m_data[3] == 0 && m_data[4] == 0 && m_data[5] == 0;
}