vendor/tendril/src/util.rs

   1 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   2 // https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   3 // <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
   4 // option. This file may not be copied, modified, or distributed
   5 // except according to those terms.
   6
   7 use std::mem;
   8 use std::{ptr, slice};
   9
  10 #[inline(always)]
  11 pub unsafe fn unsafe_slice<'a>(buf: &'a [u8], start: usize, new_len: usize) -> &'a [u8] {
  12     debug_assert!(start <= buf.len());
  13     debug_assert!(new_len <= (buf.len() - start));
  14     slice::from_raw_parts(buf.as_ptr().offset(start as isize), new_len)
  15 }
  16
  17 #[inline(always)]
  18 pub unsafe fn unsafe_slice_mut<'a>(
  19     buf: &'a mut [u8],
  20     start: usize,
  21     new_len: usize,
  22 ) -> &'a mut [u8] {
  23     debug_assert!(start <= buf.len());
  24     debug_assert!(new_len <= (buf.len() - start));
  25     slice::from_raw_parts_mut(buf.as_mut_ptr().offset(start as isize), new_len)
  26 }
  27
  28 #[inline(always)]
  29 pub unsafe fn copy_and_advance(dest: &mut *mut u8, src: &[u8]) {
  30     ptr::copy_nonoverlapping(src.as_ptr(), *dest, src.len());
  31     *dest = dest.offset(src.len() as isize)
  32 }
  33
  34 #[inline(always)]
  35 pub unsafe fn copy_lifetime_mut<'a, S: ?Sized, T: ?Sized + 'a>(
  36     _ptr: &'a mut S,
  37     ptr: &mut T,
  38 ) -> &'a mut T {
  39     mem::transmute(ptr)
  40 }
  41
  42 #[inline(always)]
  43 pub unsafe fn copy_lifetime<'a, S: ?Sized, T: ?Sized + 'a>(_ptr: &'a S, ptr: &T) -> &'a T {
  44     mem::transmute(ptr)
  45 }