feat: add __internal/memory

__internal/memory/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "memory"
+version = "0.1.0"

__internal/memory/Cargo.toml

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+[package]
+name = "memory"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

__internal/memory/README.md

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+
+Reference:
+* https://radu-matei.com/blog/practical-guide-to-wasm-memory/

__internal/memory/src/main.rs

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+#[no_mangle]
+pub fn malloc_1(len: usize) -> *mut u8 {
+    let mut buf = Vec::with_capacity(len);
+    let ptr = buf.as_mut_ptr();
+    std::mem::forget(buf);
+    return ptr;
+}
+
+#[no_mangle]
+pub fn free_1(ptr: *mut u8, len: usize) {
+    let data = unsafe { Vec::from_raw_parts(ptr, len, len) };
+    std::mem::drop(data);
+}
+
+#[no_mangle]
+pub fn malloc_2(len: usize) -> *mut u8 {
+    let align = std::mem::align_of::<usize>();
+    let layout = unsafe { std::alloc::Layout::from_size_align_unchecked(len, align) };
+    unsafe { std::alloc::alloc(layout) }
+}
+
+#[no_mangle]
+pub fn free_2(ptr: *mut u8, len: usize) {
+    let align = std::mem::align_of::<usize>();
+    let layout = unsafe { std::alloc::Layout::from_size_align_unchecked(len, align) };
+    unsafe { std::alloc::dealloc(ptr, layout) }
+}
+
+fn main() {
+    println!("Malloc-1");
+    let p = malloc_1(1024);
+    println!("Free-1");
+    free_1(p, 1024);
+
+    println!("Malloc-2");
+    let p = malloc_2(1024);
+    println!("Free-2");
+    free_2(p, 1024);
+}