BLT/include/blt/std/memory_util.h

199 lines
6.3 KiB
C++

/*
* <Short Description>
* Copyright (C) 2023 Brett Terpstra
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef BLT_MEMORY_UTIL_H
#define BLT_MEMORY_UTIL_H
#include <type_traits>
#include <array>
#include <cstring>
#include <algorithm>
#include <cstdint>
#if defined(__clang__) || defined(__llvm__) || defined(__GNUC__) || defined(__GNUG__)
#if defined(__GNUC__) || defined(__GNUG__)
#include <byteswap.h>
#define SWAP16(val) bswap_16(val)
#define SWAP32(val) bswap_32(val)
#define SWAP64(val) bswap_64(val)
#else
#define SWAP16(val) __builtin_bswap16(val)
#define SWAP32(val) __builtin_bswap32(val)
#define SWAP64(val) __builtin_bswap64(val)
#endif
#if __cplusplus >= 202002L
#include <bit>
#define ENDIAN_LOOKUP(little_endian) (std::endian::native == std::endian::little && !little_endian) || \
(std::endian::native == std::endian::big && little_endian)
#else
#define ENDIAN_LOOKUP(little_endian) !little_endian
#endif
#elif defined(_MSC_VER)
#include <intrin.h>
#define SWAP16(val) _byteswap_ushort(val)
#define SWAP32(val) _byteswap_ulong(val)
#define SWAP64(val) _byteswap_uint64(val)
#define ENDIAN_LOOKUP(little_endian) !little_endian
#endif
namespace blt::mem
{
// Used to grab the byte-data of any T element. Defaults to Big Endian, however can be configured to use little endian
template<bool little_endian = false, typename BYTE_TYPE, typename T>
inline static int toBytes(const T& in, BYTE_TYPE* out)
{
if constexpr (!(std::is_same_v<BYTE_TYPE, std::int8_t> || std::is_same_v<BYTE_TYPE, std::uint8_t>))
static_assert("Must provide a signed/unsigned int8 type");
std::memcpy(out, (void*) &in, sizeof(T));
if constexpr (ENDIAN_LOOKUP(little_endian))
{
// TODO: this but better.
for (size_t i = 0; i < sizeof(T) / 2; i++)
std::swap(out[i], out[sizeof(T) - 1 - i]);
}
return 0;
}
// Used to cast the binary data of any T object, into a T object. Assumes data is in big ending (configurable)
template<bool little_endian = false, typename BYTE_TYPE, typename T>
inline static int fromBytes(const BYTE_TYPE* in, T& out)
{
if constexpr (!(std::is_same_v<BYTE_TYPE, std::int8_t> || std::is_same_v<BYTE_TYPE, std::uint8_t>))
static_assert("Must provide a signed/unsigned int8 type");
std::array<BYTE_TYPE, sizeof(T)> data;
std::memcpy(data.data(), in, sizeof(T));
if constexpr (ENDIAN_LOOKUP(little_endian))
{
// if we need to swap find the best way to do so
if constexpr (std::is_same_v<T, int16_t> || std::is_same_v<T, uint16_t>)
out = SWAP16(*reinterpret_cast<T*>(data.data()));
else if constexpr (std::is_same_v<T, int32_t> || std::is_same_v<T, uint32_t>)
out = SWAP32(*reinterpret_cast<T*>(data.data()));
else if constexpr (std::is_same_v<T, int64_t> || std::is_same_v<T, uint64_t>)
out = SWAP64(*reinterpret_cast<T*>(data.data()));
else
{
std::reverse(data.begin(), data.end());
out = *reinterpret_cast<T*>(data.data());
}
}
return 0;
}
template<bool little_endian = false, typename BYTE_TYPE, typename T>
inline static int fromBytes(const BYTE_TYPE* in, T* out)
{
return fromBytes(in, *out);
}
inline static size_t next_byte_allocation(size_t prev_size, size_t default_allocation_block = 8192, size_t default_size = 16)
{
if (prev_size < default_size)
return default_size;
if (prev_size < default_allocation_block)
return prev_size * 2;
return prev_size + default_allocation_block;
}
template<typename R, typename T>
inline static R type_cast(T type)
{
static_assert(sizeof(T) == sizeof(R));
R r;
std::memcpy(&r, &type, sizeof(type));
return r;
}
}
namespace blt
{
template<typename V>
struct ptr_iterator
{
public:
using iterator_category = std::random_access_iterator_tag;
using difference_type = std::ptrdiff_t;
using value_type = V;
using pointer = value_type*;
using reference = value_type&;
explicit ptr_iterator(V* v): _v(v)
{}
reference operator*() const
{ return *_v; }
pointer operator->()
{ return _v; }
ptr_iterator& operator++()
{
_v++;
return *this;
}
ptr_iterator& operator--()
{
_v--;
return *this;
}
ptr_iterator operator++(int)
{
auto tmp = *this;
++(*this);
return tmp;
}
ptr_iterator operator--(int)
{
auto tmp = *this;
--(*this);
return tmp;
}
friend bool operator==(const ptr_iterator& a, const ptr_iterator& b)
{
return a._v == b._v;
}
friend bool operator!=(const ptr_iterator& a, const ptr_iterator& b)
{
return a._v != b._v;
}
private:
V* _v;
};
}
#endif //BLT_MEMORY_UTIL_H