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pageallocator.cpp
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pageallocator.cpp
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//
// pageallocator.cpp
//
// Circle - A C++ bare metal environment for Raspberry Pi
// Copyright (C) 2014-2020 R. Stange <rsta2@o2online.de>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
#include <circle/pageallocator.h>
#include <circle/logger.h>
#include <assert.h>
#define PAGE_MASK (PAGE_SIZE-1)
CPageAllocator::CPageAllocator (void)
: m_pNext (0),
m_pLimit (0),
#ifdef PAGE_DEBUG
m_nCount (0),
m_nMaxCount (0),
#endif
m_pFreeList (0)
{
}
CPageAllocator::~CPageAllocator (void)
{
}
void CPageAllocator::Setup (uintptr nBase, size_t nSize)
{
m_pNext = (u8 *) ((nBase + PAGE_SIZE-1) & ~PAGE_MASK);
m_pLimit = (u8 *) ((nBase + nSize) & ~PAGE_MASK);
}
size_t CPageAllocator::GetFreeSpace (void) const
{
return m_pLimit - m_pNext;
}
void *CPageAllocator::Allocate (void)
{
assert (m_pNext != 0);
m_SpinLock.Acquire ();
#ifdef PAGE_DEBUG
if (++m_nCount > m_nMaxCount)
{
m_nMaxCount = m_nCount;
}
#endif
TFreePage *pFreePage;
if ((pFreePage = m_pFreeList) != 0)
{
assert (pFreePage->nMagic == FREEPAGE_MAGIC);
m_pFreeList = pFreePage->pNext;
pFreePage->nMagic = 0;
}
else
{
pFreePage = (TFreePage *) m_pNext;
m_pNext += PAGE_SIZE;
if (m_pNext > m_pLimit)
{
m_SpinLock.Release ();
return 0; // TODO: system should panic here
}
}
m_SpinLock.Release ();
return pFreePage;
}
void CPageAllocator::Free (void *pPage)
{
if (pPage == 0)
{
return;
}
TFreePage *pFreePage = (TFreePage *) pPage;
m_SpinLock.Acquire ();
pFreePage->nMagic = FREEPAGE_MAGIC;
pFreePage->pNext = m_pFreeList;
m_pFreeList = pFreePage;
#ifdef PAGE_DEBUG
m_nCount--;
#endif
m_SpinLock.Release ();
}
#ifdef PAGE_DEBUG
void CPageAllocator::DumpStatus (void)
{
CLogger::Get ()->Write ("pager", LogDebug, "%u pages (max %u)", m_nCount, m_nMaxCount);
}
#endif