fix some clippy warnings

src/mem/impls.rs

@@ -1,10 +1,8 @@
-use super::c_int;
-
 #[inline(always)]
 pub unsafe fn copy_forward(dest: *mut u8, src: *const u8, n: usize) {
     let mut i = 0;
     while i < n {
-        *dest.offset(i as isize) = *src.offset(i as isize);
+        *dest.add(i) = *src.add(i);
         i += 1;
     }
 }
@@ -15,15 +13,15 @@ pub unsafe fn copy_backward(dest: *mut u8, src: *const u8, n: usize) {
     let mut i = n;
     while i != 0 {
         i -= 1;
-        *dest.offset(i as isize) = *src.offset(i as isize);
+        *dest.add(i) = *src.add(i);
     }
 }
 
 #[inline(always)]
 pub unsafe fn set_bytes(s: *mut u8, c: u8, n: usize) {
     let mut i = 0;
     while i < n {
-        *s.offset(i as isize) = c;
+        *s.add(i) = c;
         i += 1;
     }
 }

src/mem/mod.rs

@@ -45,8 +45,8 @@ pub unsafe extern "C" fn memset(s: *mut u8, c: c_int, n: usize) -> *mut u8 {
 pub unsafe extern "C" fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32 {
     let mut i = 0;
     while i < n {
-        let a = *s1.offset(i as isize);
-        let b = *s2.offset(i as isize);
+        let a = *s1.add(i);
+        let b = *s2.add(i);
         if a != b {
             return a as i32 - b as i32;
         }

src/mem/x86_64.rs

@@ -59,8 +59,8 @@ pub unsafe fn copy_backward(dest: *mut u8, src: *const u8, count: usize) {
         "cld",
         byte_count = in(reg) byte_count,
         inout("rcx") qword_count => _,
-        inout("rdi") dest.offset(count as isize).wrapping_sub(8) => _,
-        inout("rsi") src.offset(count as isize).wrapping_sub(8) => _,
+        inout("rdi") dest.add(count).wrapping_sub(8) => _,
+        inout("rsi") src.add(count).wrapping_sub(8) => _,
         options(nostack)
     );
 }