run_cursor.h

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/***************************************************************************
 * include/stxxl/bits/algo/run_cursor.h
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2003 Roman Dementiev <[email protected]>
 * Copyright (C) 2009 Andreas Beckmann <[email protected]>
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 **************************************************************************/

#ifndef STXXL_ALGO_RUN_CURSOR_HEADER
#define STXXL_ALGO_RUN_CURSOR_HEADER

#include <cstdlib>
#include <stxxl/bits/common/types.h>


STXXL_BEGIN_NAMESPACE

template <typename block_type>
struct run_cursor
{
 unsigned_type pos;
 block_type* buffer;

 run_cursor() : pos(0), buffer(NULL) { }

 inline typename block_type::const_reference current() const
 {
 return (*buffer)[pos];
 }
 inline void operator ++ ()
 {
 ++pos;
 }
};

#ifdef STXXL_SORT_SINGLE_PREFETCHER

template <typename must_be_void = void>
struct have_prefetcher
{
 static void* untyped_prefetcher;
};

#endif

template <typename block_type,
 typename prefetcher_type_>
struct run_cursor2 : public run_cursor<block_type>
#ifdef STXXL_SORT_SINGLE_PREFETCHER
 , public have_prefetcher<>
#endif
{
 typedef prefetcher_type_ prefetcher_type;
 typedef run_cursor2<block_type, prefetcher_type> _Self;
 typedef typename block_type::value_type value_type;

 using run_cursor<block_type>::pos;
 using run_cursor<block_type>::buffer;

#ifdef STXXL_SORT_SINGLE_PREFETCHER
 static prefetcher_type* const prefetcher() // sorry, a hack
 {
 return reinterpret_cast<prefetcher_type*>(untyped_prefetcher);
 }
 static void set_prefetcher(prefetcher_type* pfptr)
 {
 untyped_prefetcher = pfptr;
 }
 run_cursor2() { }
#else
 prefetcher_type* prefetcher_;
 prefetcher_type* & prefetcher() // sorry, a hack
 {
 return prefetcher_;
 }

 run_cursor2(prefetcher_type* p = NULL) : prefetcher_(p) { }
#endif

 inline bool empty() const
 {
 return (pos >= block_type::size);
 }
 inline void operator ++ ();
 inline void make_inf()
 {
 pos = block_type::size;
 }
};

#ifdef STXXL_SORT_SINGLE_PREFETCHER
template <typename must_be_void>
void* have_prefetcher<must_be_void>::untyped_prefetcher = NULL;
#endif

template <typename block_type,
 typename prefetcher_type>
void run_cursor2<block_type, prefetcher_type>::operator ++ ()
{
 assert(!empty());
 ++pos;
 if (UNLIKELY(pos >= block_type::size))
 {
 if (prefetcher()->block_consumed(buffer))
 pos = 0;
 }
}


#if 0
template <typename block_type>
struct run_cursor_cmp
{
 typedef run_cursor<block_type> cursor_type;

 inline bool operator () (const cursor_type& a, const cursor_type& b) // greater or equal
 {
 return !((*a.buffer)[a.pos] < (*b.buffer)[b.pos]);
 }
};
#endif

STXXL_END_NAMESPACE


#endif // !STXXL_ALGO_RUN_CURSOR_HEADER
// vim: et:ts=4:sw=4