Initializing static array with contents of (static and dynamic) arrays
Ali Çehreli via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Mon Jul 4 11:33:56 PDT 2016
On 07/04/2016 07:31 AM, Johannes Loher wrote:
> In a project I am currently working on, I have lot's of code of the
> following form:
>
> static immutable ubyte[4] sigma0 = [101, 120, 112, 97];
> static immutable ubyte[4] sigma1 = [110, 100, 32, 51];
> static immutable ubyte[4] sigma2 = [ 50, 45, 98, 121];
> static immutable ubyte[4] sigma3 = [116, 101, 32, 107];
>
> void func(in ubyte[32] key, in ubyte[16] n)
> {
> ubyte[64] buf;
> buf[0..4] = sigma0;
> buf[4..20] = key[0..16];
> buf[20..24] = sigma1;
> buf[24..40] = n;
> buf[40..44] = sigma2;
> buf[44..60] = key[16..$];
> buf[60..64] = sigma3;
>
> /* do something with buf */
> }
Here's an option that overlays a struct on top of the bytes:
struct Buf {
union {
struct {
ubyte[4] sigma0 = [101, 120, 112, 97];
ubyte[16] keyBeg;
ubyte[4] sigma1 = [110, 100, 32, 51];
ubyte[16] n;
ubyte[4] sigma2 = [ 50, 45, 98, 121];
ubyte[16] keyEnd;
ubyte[4] sigma3 = [116, 101, 32, 107];
}
ubyte[64] bytes;
}
this(const ubyte[] key, const ubyte[] n) {
this.keyBeg = key[0..16];
this.keyEnd = key[16..$];
this.n = n;
}
}
static assert(Buf.sizeof == 64);
void func(in ubyte[] key, in ubyte[] n) {
auto buf = Buf(key, n);
writeln(buf.bytes);
}
import std.stdio;
import std.range;
import std.array;
void main() {
func(ubyte(32).iota.array,
ubyte(16).iota.array);
}
Prints:
[101, 120, 112, 97, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 110, 100, 32, 51, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 50, 45, 98, 121, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
29, 30, 31, 116, 101, 32, 107]
Ali
More information about the Digitalmars-d-learn
mailing list