BEType.h: use common initial sequance in v128

Partially obey 'strict type aliasing' rule.
This commit is contained in:
Eladash 2020-03-17 15:05:42 +02:00 committed by Ivan
parent 03a6d67c6c
commit c9b5ba4a5c

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@ -18,17 +18,17 @@ union alignas(16) v128
template <typename T, std::size_t N, std::size_t M>
struct masked_array_t // array type accessed as (index ^ M)
{
T m_data[N];
char m_data[16];
public:
T& operator[](std::size_t index)
{
return m_data[index ^ M];
return reinterpret_cast<T*>(m_data)[index ^ M];
}
const T& operator[](std::size_t index) const
{
return m_data[index ^ M];
return reinterpret_cast<const T*>(m_data)[index ^ M];
}
};
@ -68,7 +68,7 @@ union alignas(16) v128
struct bit_array_128
{
u64 m_data[2];
char m_data[16];
public:
class bit_element
@ -118,26 +118,30 @@ union alignas(16) v128
// Index 0 returns the MSB and index 127 returns the LSB
bit_element operator[](u32 index)
{
const auto data_ptr = reinterpret_cast<u64*>(m_data);
if constexpr (std::endian::little == std::endian::native)
{
return bit_element(m_data[1 - (index >> 6)], 0x8000000000000000ull >> (index & 0x3F));
return bit_element(data_ptr[1 - (index >> 6)], 0x8000000000000000ull >> (index & 0x3F));
}
else
{
return bit_element(m_data[index >> 6], 0x8000000000000000ull >> (index & 0x3F));
return bit_element(data_ptr[index >> 6], 0x8000000000000000ull >> (index & 0x3F));
}
}
// Index 0 returns the MSB and index 127 returns the LSB
bool operator[](u32 index) const
{
const auto data_ptr = reinterpret_cast<const u64*>(m_data);
if constexpr (std::endian::little == std::endian::native)
{
return (m_data[1 - (index >> 6)] & (0x8000000000000000ull >> (index & 0x3F))) != 0;
return (data_ptr[1 - (index >> 6)] & (0x8000000000000000ull >> (index & 0x3F))) != 0;
}
else
{
return (m_data[index >> 6] & (0x8000000000000000ull >> (index & 0x3F))) != 0;
return (data_ptr[index >> 6] & (0x8000000000000000ull >> (index & 0x3F))) != 0;
}
}
} _bit;