aligned_alloc_via_malloc()

void * fl::detail::aligned_alloc_via_malloc	(	fl::size_t	alignment,
		fl::size_t	size )

Portable over-allocate-and-align used by aligned_alloc on bare-metal targets; free only with aligned_free_via_malloc (#4817).

Definition at line 27 of file cstdlib.cpp.hpp.

                                                                               {
    if (alignment < sizeof(void *)) {
        alignment = sizeof(void *);
    }
    if ((alignment & (alignment - 1)) != 0) {
        return nullptr;  // alignment must be a power of two
    }
    const fl::size_t overhead = alignment - 1 + sizeof(void *);
    if (size > static_cast<fl::size_t>(-1) - overhead) {
        return nullptr;  // size + overhead would wrap
    }
    void *raw = ::malloc(size + overhead);
    if (raw == nullptr) {
        return nullptr;
    }
    const fl::uptr start = fl::reinterpret_cast_<fl::uptr>(raw) + sizeof(void *);
    const fl::uptr aligned = (start + alignment - 1) & ~(fl::uptr(alignment) - 1);
    void **slot = fl::reinterpret_cast_<void **>(aligned);
    slot[-1] = raw;
    return slot;
}

References fl::FL_NO_EXCEPT, fl::malloc(), and fl::reinterpret_cast_().

Referenced by fl::libc_impl::aligned_alloc().

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