| 1 | const std = @import("std"); |
| 2 | const native_endian = @import("builtin").target.cpu.arch.endian(); |
| 3 | const expectEqual = std.testing.expectEqual; |
| 4 | |
| 5 | test "pointer casting" { |
| 6 | const bytes: [4]u8 align(@alignOf(u32)) = .{ 0x10, 0x20, 0x30, 0x40 }; |
| 7 | const u32_ptr: *const u32 = @ptrCast(&bytes); |
| 8 | |
| 9 | // Because we directly reinterpreted bytes of memory, the `u32` value we |
| 10 | // load from `u32_ptr` depends on the target endian: |
| 11 | switch (native_endian) { |
| 12 | .little => try expectEqual(0x40302010, u32_ptr.*), |
| 13 | .big => try expectEqual(0x10203040, u32_ptr.*), |
| 14 | } |
| 15 | |
| 16 | // To instead reinterpret the logical bit representation of `bytes` with no |
| 17 | // dependency on the target endian, use `@bitCast`, which always places |
| 18 | // earlier array elements into less-significant bits: |
| 19 | try expectEqual(0x40302010, @as(u32, @bitCast(bytes))); |
| 20 | } |
| 21 | |
| 22 | test "pointer child type" { |
| 23 | // pointer types have a `child` field which tells you the type they point to. |
| 24 | try expectEqual(u32, @typeInfo(*u32).pointer.child); |
| 25 | } |
| 26 | |
| 27 | // test |