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