| // Aligned to two bytes |
| const DATA: [u16; 2] = [u16::from_ne_bytes([0x01, 0x23]), u16::from_ne_bytes([0x45, 0x67])]; |
| |
| const fn unaligned_ptr() -> *const u16 { |
| // Since DATA.as_ptr() is aligned to two bytes, adding 1 byte to that produces an unaligned *const u16 |
| unsafe { DATA.as_ptr().byte_add(1) } |
| } |
| |
| #[test] |
| fn read() { |
| use core::ptr; |
| |
| const FOO: i32 = unsafe { ptr::read(&42 as *const i32) }; |
| assert_eq!(FOO, 42); |
| |
| const ALIGNED: i32 = unsafe { ptr::read_unaligned(&42 as *const i32) }; |
| assert_eq!(ALIGNED, 42); |
| |
| const UNALIGNED_PTR: *const u16 = unaligned_ptr(); |
| |
| const UNALIGNED: u16 = unsafe { ptr::read_unaligned(UNALIGNED_PTR) }; |
| assert_eq!(UNALIGNED, u16::from_ne_bytes([0x23, 0x45])); |
| } |
| |
| #[test] |
| fn const_ptr_read() { |
| const FOO: i32 = unsafe { (&42 as *const i32).read() }; |
| assert_eq!(FOO, 42); |
| |
| const ALIGNED: i32 = unsafe { (&42 as *const i32).read_unaligned() }; |
| assert_eq!(ALIGNED, 42); |
| |
| const UNALIGNED_PTR: *const u16 = unaligned_ptr(); |
| |
| const UNALIGNED: u16 = unsafe { UNALIGNED_PTR.read_unaligned() }; |
| assert_eq!(UNALIGNED, u16::from_ne_bytes([0x23, 0x45])); |
| } |
| |
| #[test] |
| fn mut_ptr_read() { |
| const FOO: i32 = unsafe { (&42 as *const i32 as *mut i32).read() }; |
| assert_eq!(FOO, 42); |
| |
| const ALIGNED: i32 = unsafe { (&42 as *const i32 as *mut i32).read_unaligned() }; |
| assert_eq!(ALIGNED, 42); |
| |
| const UNALIGNED_PTR: *mut u16 = unaligned_ptr() as *mut u16; |
| |
| const UNALIGNED: u16 = unsafe { UNALIGNED_PTR.read_unaligned() }; |
| assert_eq!(UNALIGNED, u16::from_ne_bytes([0x23, 0x45])); |
| } |
| |
| #[test] |
| fn write() { |
| use core::ptr; |
| |
| const fn write_aligned() -> i32 { |
| let mut res = 0; |
| unsafe { |
| ptr::write(&mut res as *mut _, 42); |
| } |
| res |
| } |
| const ALIGNED: i32 = write_aligned(); |
| assert_eq!(ALIGNED, 42); |
| |
| const fn write_unaligned() -> [u16; 2] { |
| let mut two_aligned = [0u16; 2]; |
| unsafe { |
| let unaligned_ptr = two_aligned.as_mut_ptr().byte_add(1); |
| ptr::write_unaligned(unaligned_ptr, u16::from_ne_bytes([0x23, 0x45])); |
| } |
| two_aligned |
| } |
| const UNALIGNED: [u16; 2] = write_unaligned(); |
| assert_eq!(UNALIGNED, [u16::from_ne_bytes([0x00, 0x23]), u16::from_ne_bytes([0x45, 0x00])]); |
| } |
| |
| #[test] |
| fn mut_ptr_write() { |
| const fn aligned() -> i32 { |
| let mut res = 0; |
| unsafe { |
| (&mut res as *mut i32).write(42); |
| } |
| res |
| } |
| const ALIGNED: i32 = aligned(); |
| assert_eq!(ALIGNED, 42); |
| |
| const fn write_unaligned() -> [u16; 2] { |
| let mut two_aligned = [0u16; 2]; |
| unsafe { |
| let unaligned_ptr = two_aligned.as_mut_ptr().byte_add(1); |
| unaligned_ptr.write_unaligned(u16::from_ne_bytes([0x23, 0x45])); |
| } |
| two_aligned |
| } |
| const UNALIGNED: [u16; 2] = write_unaligned(); |
| assert_eq!(UNALIGNED, [u16::from_ne_bytes([0x00, 0x23]), u16::from_ne_bytes([0x45, 0x00])]); |
| } |