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/**
* Contains a bitfield used by the GC.
*
* Copyright: Copyright Digital Mars 2005 - 2013.
* License: $(WEB www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
* Authors: Walter Bright, David Friedman, Sean Kelly
*/
/* Copyright Digital Mars 2005 - 2013.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*/
module gc.bits;
import core.bitop;
import core.stdc.string;
import core.stdc.stdlib;
import core.exception : onOutOfMemoryError;
struct GCBits
{
alias size_t wordtype;
enum BITS_PER_WORD = (wordtype.sizeof * 8);
enum BITS_SHIFT = (wordtype.sizeof == 8 ? 6 : 5);
enum BITS_MASK = (BITS_PER_WORD - 1);
enum BITS_1 = cast(wordtype)1;
wordtype* data;
size_t nbits;
void Dtor() nothrow
{
if (data)
{
free(data);
data = null;
}
}
void alloc(size_t nbits) nothrow
{
this.nbits = nbits;
data = cast(typeof(data[0])*)calloc(nwords, data[0].sizeof);
if (!data)
onOutOfMemoryError();
}
wordtype test(size_t i) const nothrow
in
{
assert(i < nbits);
}
body
{
return core.bitop.bt(data, i);
}
int set(size_t i) nothrow
in
{
assert(i < nbits);
}
body
{
return core.bitop.bts(data, i);
}
int clear(size_t i) nothrow
in
{
assert(i <= nbits);
}
body
{
return core.bitop.btr(data, i);
}
void zero() nothrow
{
memset(data, 0, nwords * wordtype.sizeof);
}
void copy(GCBits *f) nothrow
in
{
assert(nwords == f.nwords);
}
body
{
memcpy(data, f.data, nwords * wordtype.sizeof);
}
@property size_t nwords() const pure nothrow
{
return (nbits + (BITS_PER_WORD - 1)) >> BITS_SHIFT;
}
}
unittest
{
GCBits b;
b.alloc(786);
assert(!b.test(123));
assert(!b.clear(123));
assert(!b.set(123));
assert(b.test(123));
assert(b.clear(123));
assert(!b.test(123));
b.set(785);
b.set(0);
assert(b.test(785));
assert(b.test(0));
b.zero();
assert(!b.test(785));
assert(!b.test(0));
GCBits b2;
b2.alloc(786);
b2.set(38);
b.copy(&b2);
assert(b.test(38));
b2.Dtor();
b.Dtor();
}