diff --git a/src/c/wasm.rs b/src/c/wasm.rs
index 644123b..579f2a9 100644
--- a/src/c/wasm.rs
+++ b/src/c/wasm.rs
@@ -853,19 +853,210 @@ unsafe extern "C" fn spine_free(ptr: *mut c_void) {
 }
 
 #[no_mangle]
-unsafe extern "C" fn spine_memcpy(dest: *mut c_void, src: *const c_void, n: size_t) -> *mut c_void {
-    std::ptr::copy_nonoverlapping(src, dest, n as usize);
-    dest
+unsafe extern "C" fn spine_memcpy(
+    dst0: *mut c_void,
+    src0: *const c_void,
+    mut length: size_t,
+) -> *mut c_void {
+    type Word = size_t;
+    let mut dst: *mut c_char = dst0.cast::<c_char>();
+    let mut src: *const c_char = src0.cast::<c_char>();
+    let mut t: size_t;
+    if !(length == 0 as c_int as c_ulong || dst.cast_const() == src) {
+        if dst < src.cast_mut() && dst.offset(length as isize) > src.cast_mut()
+            || src < dst.cast_const() && src.offset(length as isize) > dst.cast_const()
+        {
+            panic!();
+        }
+        t = src as c_long as size_t;
+        if (t | dst as c_long as c_ulong)
+            & (::core::mem::size_of::<Word>() as c_ulong).wrapping_sub(1 as c_int as c_ulong)
+            != 0
+        {
+            if (t ^ dst as c_long as c_ulong)
+                & (::core::mem::size_of::<Word>() as c_ulong).wrapping_sub(1 as c_int as c_ulong)
+                != 0
+                || length < ::core::mem::size_of::<Word>() as c_ulong
+            {
+                t = length;
+            } else {
+                t = (::core::mem::size_of::<Word>() as c_ulong).wrapping_sub(
+                    t & (::core::mem::size_of::<Word>() as c_ulong)
+                        .wrapping_sub(1 as c_int as c_ulong),
+                );
+            }
+            length = (length as c_ulong).wrapping_sub(t) as size_t as size_t;
+            loop {
+                let fresh0 = src;
+                src = src.offset(1);
+                let fresh1 = dst;
+                dst = dst.offset(1);
+                *fresh1 = *fresh0;
+                t = t.wrapping_sub(1);
+                if t == 0 {
+                    break;
+                }
+            }
+        }
+        t = length.wrapping_div(::core::mem::size_of::<Word>() as c_ulong);
+        if t != 0 {
+            loop {
+                *dst.cast::<Word>() = *(src as *mut Word);
+                src = src.offset(::core::mem::size_of::<Word>() as c_ulong as isize);
+                dst = dst.offset(::core::mem::size_of::<Word>() as c_ulong as isize);
+                t = t.wrapping_sub(1);
+                if t == 0 {
+                    break;
+                }
+            }
+        }
+        t = length
+            & (::core::mem::size_of::<Word>() as c_ulong).wrapping_sub(1 as c_int as c_ulong);
+        if t != 0 {
+            loop {
+                let fresh2 = src;
+                src = src.offset(1);
+                let fresh3 = dst;
+                dst = dst.offset(1);
+                *fresh3 = *fresh2;
+                t = t.wrapping_sub(1);
+                if t == 0 {
+                    break;
+                }
+            }
+        }
+    }
+    dst0
 }
 
 #[no_mangle]
 unsafe extern "C" fn spine_memmove(
-    dest: *mut c_void,
-    src: *const c_void,
-    n: size_t,
+    dst0: *mut c_void,
+    src0: *const c_void,
+    mut length: size_t,
 ) -> *mut c_void {
-    std::ptr::copy(src, dest, n as usize);
-    dest
+    type Word = size_t;
+    let mut dst: *mut c_char = dst0.cast::<c_char>();
+    let mut src: *const c_char = src0.cast::<c_char>();
+    let mut t: size_t;
+    if !(length == 0 as c_int as c_ulong || dst.cast_const() == src) {
+        if (dst as c_ulong) < src as c_ulong {
+            t = src as c_long as size_t;
+            if (t | dst as c_long as c_ulong)
+                & (::core::mem::size_of::<Word>() as c_ulong).wrapping_sub(1 as c_int as c_ulong)
+                != 0
+            {
+                if (t ^ dst as c_long as c_ulong)
+                    & (::core::mem::size_of::<Word>() as c_ulong)
+                        .wrapping_sub(1 as c_int as c_ulong)
+                    != 0
+                    || length < ::core::mem::size_of::<Word>() as c_ulong
+                {
+                    t = length;
+                } else {
+                    t = (::core::mem::size_of::<Word>() as c_ulong).wrapping_sub(
+                        t & (::core::mem::size_of::<Word>() as c_ulong)
+                            .wrapping_sub(1 as c_int as c_ulong),
+                    );
+                }
+                length = (length as c_ulong).wrapping_sub(t) as size_t as size_t;
+                loop {
+                    let fresh0 = src;
+                    src = src.offset(1);
+                    let fresh1 = dst;
+                    dst = dst.offset(1);
+                    *fresh1 = *fresh0;
+                    t = t.wrapping_sub(1);
+                    if t == 0 {
+                        break;
+                    }
+                }
+            }
+            t = length.wrapping_div(::core::mem::size_of::<Word>() as c_ulong);
+            if t != 0 {
+                loop {
+                    *dst.cast::<Word>() = *(src as *mut Word);
+                    src = src.offset(::core::mem::size_of::<Word>() as c_ulong as isize);
+                    dst = dst.offset(::core::mem::size_of::<Word>() as c_ulong as isize);
+                    t = t.wrapping_sub(1);
+                    if t == 0 {
+                        break;
+                    }
+                }
+            }
+            t = length
+                & (::core::mem::size_of::<Word>() as c_ulong).wrapping_sub(1 as c_int as c_ulong);
+            if t != 0 {
+                loop {
+                    let fresh2 = src;
+                    src = src.offset(1);
+                    let fresh3 = dst;
+                    dst = dst.offset(1);
+                    *fresh3 = *fresh2;
+                    t = t.wrapping_sub(1);
+                    if t == 0 {
+                        break;
+                    }
+                }
+            }
+        } else {
+            src = src.offset(length as isize);
+            dst = dst.offset(length as isize);
+            t = src as c_long as size_t;
+            if (t | dst as c_long as c_ulong)
+                & (::core::mem::size_of::<Word>() as c_ulong).wrapping_sub(1 as c_int as c_ulong)
+                != 0
+            {
+                if (t ^ dst as c_long as c_ulong)
+                    & (::core::mem::size_of::<Word>() as c_ulong)
+                        .wrapping_sub(1 as c_int as c_ulong)
+                    != 0
+                    || length <= ::core::mem::size_of::<Word>() as c_ulong
+                {
+                    t = length;
+                } else {
+                    t &= (::core::mem::size_of::<Word>() as c_ulong)
+                        .wrapping_sub(1 as c_int as c_ulong);
+                }
+                length = (length as c_ulong).wrapping_sub(t) as size_t as size_t;
+                loop {
+                    src = src.offset(-1);
+                    dst = dst.offset(-1);
+                    *dst = *src;
+                    t = t.wrapping_sub(1);
+                    if t == 0 {
+                        break;
+                    }
+                }
+            }
+            t = length.wrapping_div(::core::mem::size_of::<Word>() as c_ulong);
+            if t != 0 {
+                loop {
+                    src = src.offset(-(::core::mem::size_of::<Word>() as c_ulong as isize));
+                    dst = dst.offset(-(::core::mem::size_of::<Word>() as c_ulong as isize));
+                    *dst.cast::<Word>() = *(src as *mut Word);
+                    t = t.wrapping_sub(1);
+                    if t == 0 {
+                        break;
+                    }
+                }
+            }
+            t = length
+                & (::core::mem::size_of::<Word>() as c_ulong).wrapping_sub(1 as c_int as c_ulong);
+            if t != 0 {
+                loop {
+                    src = src.offset(-1);
+                    dst = dst.offset(-1);
+                    *dst = *src;
+                    t = t.wrapping_sub(1);
+                    if t == 0 {
+                        break;
+                    }
+                }
+            }
+        }
+    }
+    dst0
 }
 
 #[no_mangle]