On Thursday, 24 October 2019 at 13:33:30 UTC, 9898287 wrote:
What's the function for converting a ulong to a native-endian
byte array?
For example,
auto bytes = 0x1234567890123456u64.to_ne_bytes();
// should yield
// [0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56] in
big-endian and
// [0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12] in
little-endian systems
Also, what's the function for constructing a ulong from a
native-endian byte array?
For example,
auto value = from_be_bytes!ulong([0x12, 0x34, 0x56, 0x78, 0x90,
0x12, 0x34, 0x56]);
// value is 0x1234567890123456
Rust equivalent:
https://doc.rust-lang.org/std/primitive.u64.html#method.to_ne_bytes
Use a cast:
ulong n = 0x1122334455667788;
ubyte[] bytes = (cast(ubyte*) &n)[0 .. n.sizeof];
ulong m = *cast(ulong*) bytes.ptr;
assert(m == n);
Note that if you're writing code that cares about the native byte
order, there's a good chance you're making a mistake. Rob Pike
has written a blog post titled "The byte order fallacy"
discussing this in more detail:
https://commandcenter.blogspot.com/2012/04/byte-order-fallacy.html
If you need to convert between native byte order and big/little
endian byte arrays (e.g., for serialization/deserialization),
there are functions in `std.bitmanip` that you can use:
https://dlang.org/phobos/std_bitmanip.html
