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/**
* Implementation of array cast support routines.
*
* Copyright: Copyright Digital Mars 2004 - 2016.
* License: Distributed under the
* $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost Software License 1.0).
* Authors: Walter Bright, Sean Kelly
* Source: $(DRUNTIMESRC src/rt/_arraycast.d)
*/
module rt.arraycast;
/******************************************
* Runtime helper to convert dynamic array of one
* type to dynamic array of another.
* Adjusts the length of the array.
* Throws an error if new length is not aligned.
*/
extern (C)
@trusted nothrow
void[] _d_arraycast(size_t tsize, size_t fsize, void[] a)
{
auto length = a.length;
auto nbytes = length * fsize;
if (nbytes % tsize != 0)
{
throw new Error("array cast misalignment");
}
length = nbytes / tsize;
*cast(size_t *)&a = length; // jam new length
return a;
}
unittest
{
byte[int.sizeof * 3] b;
int[] i;
short[] s;
i = cast(int[])b;
assert(i.length == 3);
s = cast(short[])b;
assert(s.length == 6);
s = cast(short[])i;
assert(s.length == 6);
}
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