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002_grammar_align.cpp
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002_grammar_align.cpp
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#include <iostream>
#include <memory>
template <std::size_t N>
struct MyAllocator
{
char data[N];
void* p;
std::size_t sz;
MyAllocator() : p(data), sz(N) {}
template <typename T>
T* aligned_alloc(std::size_t a = alignof(T))
{
if (std::align(a, sizeof(T), p, sz))
{
T* result = reinterpret_cast<T*>(p);
p = (char*)p + sizeof(T);
sz -= sizeof(T);
return result;
}
return nullptr;
}
};
int main()
{
MyAllocator<64> a;
// allocate a char
char* p1 = a.aligned_alloc<char>();
if (p1)
*p1 = 'a';
std::cout << "allocated a char at " << (void*)p1 << '\n';
// allocate an int
int* p2 = a.aligned_alloc<int>();
if (p2)
*p2 = 1;
std::cout << "allocated an int at " << (void*)p2 << '\n';
// allocate an int, aligned at 32-byte boundary
int* p3 = a.aligned_alloc<int>(32);
if (p3)
*p3 = 2;
std::cout << "allocated an int at " << (void*)p3 << " (32 byte alignment)\n";
}