c代码如下

static inline void **alignPointer(void **ptr, size_t alignment) {
    return (void **)((intptr_t)((unsigned char *)ptr + alignment - 1) & -alignment);
}

extern "C" void *MemoryAllocAlign(size_t size, size_t alignment) {
    ASSERT(size > 0);

    void **origin = (void **)malloc(size + sizeof(void *) + alignment);
    ASSERT(origin != NULL);
    if (!origin) {
        return NULL;
    }
    void **aligned = alignPointer(origin + 1, alignment);
    aligned[-1]    = origin;
    return aligned;

}

extern "C" void MemoryFreeAlign(void *aligned) {
    if (aligned) {
        void *origin = ((void **)aligned)[-1];
        free(origin);
    }
}

我实现的rust部分代码

[cfg_attr(feature = "cargo-clippy", allow(clippy::inline_always))]
#[inline(always)]
fn align_size(v: size_t, n: size_t) -> size_t {
    v.wrapping_add(n).wrapping_sub(1) & !n.wrapping_sub(1)
}

#[cfg_attr(feature = "cargo-clippy", allow(clippy::inline_always))]
#[inline(always)]
fn align_ptr(v: *mut *mut c_void, n: size_t) ->  *mut *mut c_void {
    unsafe {
        ((v as  size_t).wrapping_add(n).wrapping_sub(1) & !n.wrapping_sub(1)) as *mut *mut c_void
    }
}
use core::mem::size_of;
use core::slice;
pub unsafe trait MyAlloc{
    unsafe fn fast_malloc(&self, size: size_t, alignment: size_t) -> *mut c_void {
        if cfg!(target_os = "linux") && unlikely(size == 0) {
            return ptr::null_mut();
        }
        unsafe{
            let udata = libc::malloc(size + size_of::<*mut  c_void>() as size_t + alignment)as *mut c_uchar;
            if  udata.is_null(){
                return ptr::null_mut();
            }
            let adata = align_ptr(  (&mut udata as *mut *mut c_uchar as *mut *mut c_void).wrapping_add(1),alignment);
            //adata[-1] = udata; 这部分不知道怎么实现。。。。
            //return adata;
        }
    }
}

希望大佬帮忙看看，没有问题