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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* 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 2
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
* This file contains the handle based Memory Manager code.
*/
#include "tinsel/heapmem.h"
#include "tinsel/timers.h" // For DwGetCurrentTime
#include "tinsel/tinsel.h"
namespace Tinsel {
// internal allocation flags
#define DWM_USED 0x0001 ///< the objects memory block is in use
#define DWM_DISCARDED 0x0100 ///< the objects memory block has been discarded
#define DWM_LOCKED 0x0200 ///< the objects memory block is locked
#define DWM_SENTINEL 0x0400 ///< the objects memory block is a sentinel
// Specifies the total amount of memory required for DW1 demo, DW1, or DW2 respectively.
// Currently this is set at 5MB for the DW1 demo and DW1 and 10MB for DW2
// This could probably be reduced somewhat
// If the memory is not enough, the engine throws an "Out of memory" error in handle.cpp inside LockMem()
static const uint32 MemoryPoolSize[3] = {5 * 1024 * 1024, 5 * 1024 * 1024, 10 * 1024 * 1024};
// list of all memory nodes
MEM_NODE mnodeList[NUM_MNODES];
// pointer to the linked list of free mnodes
static MEM_NODE *pFreeMemNodes;
#ifdef DEBUG
// diagnostic mnode counters
static int numNodes;
static int maxNodes;
#endif
// the mnode heap sentinel
static MEM_NODE heapSentinel;
//
static MEM_NODE *AllocMemNode(void);
/**
* Initialises the memory manager.
*/
void MemoryInit(void) {
MEM_NODE *pNode;
#ifdef DEBUG
// clear number of nodes in use
numNodes = 0;
#endif
// place first node on free list
pFreeMemNodes = mnodeList;
// link all other objects after first
for (int i = 1; i < NUM_MNODES; i++) {
mnodeList[i - 1].pNext = mnodeList + i;
}
// null the last mnode
mnodeList[NUM_MNODES - 1].pNext = NULL;
// allocates a big chunk of memory
uint32 size = MemoryPoolSize[0];
if (TinselVersion == TINSEL_V1) size = MemoryPoolSize[1];
else if (TinselVersion == TINSEL_V2) size = MemoryPoolSize[2];
uint8 *mem = (uint8 *)malloc(size);
assert(mem);
// allocate a mnode for this memory
pNode = AllocMemNode();
// make sure mnode was allocated
assert(pNode);
// convert segment to memory address
pNode->pBaseAddr = mem;
// set size of the memory heap
pNode->size = size;
// clear the memory
memset(pNode->pBaseAddr, 0, size);
// set cyclic links to the sentinel
heapSentinel.pPrev = pNode;
heapSentinel.pNext = pNode;
pNode->pPrev = &heapSentinel;
pNode->pNext = &heapSentinel;
// flag sentinel as locked
heapSentinel.flags = DWM_LOCKED | DWM_SENTINEL;
}
/**
* Allocate a mnode from the free list.
*/
static MEM_NODE *AllocMemNode(void) {
// get the first free mnode
MEM_NODE *pMemNode = pFreeMemNodes;
// make sure a mnode is available
assert(pMemNode); // Out of memory nodes
// the next free mnode
pFreeMemNodes = pMemNode->pNext;
// wipe out the mnode
memset(pMemNode, 0, sizeof(MEM_NODE));
#ifdef DEBUG
// one more mnode in use
if (++numNodes > maxNodes)
maxNodes = numNodes;
#endif
// return new mnode
return pMemNode;
}
/**
* Return a mnode back to the free list.
* @param pMemNode Node of the memory object
*/
void FreeMemNode(MEM_NODE *pMemNode) {
// validate mnode pointer
assert(pMemNode >= mnodeList && pMemNode <= mnodeList + NUM_MNODES - 1);
#ifdef DEBUG
// one less mnode in use
--numNodes;
assert(numNodes >= 0);
#endif
// place free list in mnode next
pMemNode->pNext = pFreeMemNodes;
// add mnode to top of free list
pFreeMemNodes = pMemNode;
}
/**
* Tries to make space for the specified number of bytes on the specified heap.
* @param size Number of bytes to free up
* @param bDiscard When set - will discard blocks to fullfill the request
* @return true if any blocks were discarded, false otherwise
*/
bool HeapCompact(long size, bool bDiscard) {
MEM_NODE *pHeap = &heapSentinel;
MEM_NODE *pPrev, *pCur, *pOldest;
long largest; // size of largest free block
uint32 oldest; // time of the oldest discardable block
while (true) {
bool bChanged;
do {
bChanged = false;
for (pPrev = pHeap->pNext, pCur = pPrev->pNext;
pCur != pHeap; pPrev = pCur, pCur = pCur->pNext) {
if (pPrev->flags == 0 && pCur->flags == 0) {
// both blocks are free - merge them
pPrev->size += pCur->size;
// unlink the current mnode
pPrev->pNext = pCur->pNext;
pCur->pNext->pPrev = pPrev;
// free the current mnode
FreeMemNode(pCur);
// set the changed flag
bChanged = true;
// leave the loop
break;
} else if (pPrev->flags == DWM_USED && pCur->flags == 0) {
// a free block after a moveable, non-discarded, not locked block - swap them
// set the changed flag
bChanged = true;
// move the unlocked blocks data up (can overlap)
memmove(pPrev->pBaseAddr + pCur->size, pPrev->pBaseAddr, pPrev->size);
// swap the order in the linked list
pPrev->pPrev->pNext = pCur;
pCur->pNext->pPrev = pPrev;
pCur->pPrev = pPrev->pPrev;
pPrev->pPrev = pCur;
pPrev->pNext = pCur->pNext;
pCur->pNext = pPrev;
pCur->pBaseAddr = pPrev->pBaseAddr;
pPrev->pBaseAddr += pCur->size;
// leave the loop
break;
}
}
} while (bChanged);
// find the largest free block
for (largest = 0, pCur = pHeap->pNext; pCur != pHeap; pCur = pCur->pNext) {
if (pCur->flags == 0 && pCur->size > largest)
largest = pCur->size;
}
if (largest >= size)
// we have freed enough memory
return true;
if (!bDiscard)
// we cannot free enough without discarding blocks
return false;
// find the oldest discardable block
oldest = DwGetCurrentTime();
pOldest = NULL;
for (pCur = pHeap->pNext; pCur != pHeap; pCur = pCur->pNext) {
if (pCur->flags == DWM_USED) {
// found a non-discarded discardable block
if (pCur->lruTime < oldest) {
oldest = pCur->lruTime;
pOldest = pCur;
}
}
}
if (pOldest)
// discard the oldest block
MemoryDiscard(pOldest);
else
// cannot discard any blocks
return false;
}
}
/**
* Allocates the specified number of bytes from the heap.
* @param flags Allocation attributes
* @param size Number of bytes to allocate
*/
static MEM_NODE *MemoryAlloc(long size) {
const MEM_NODE *pHeap = &heapSentinel;
MEM_NODE *pNode;
#ifdef SCUMM_NEED_ALIGNMENT
const int alignPadding = sizeof(void*) - 1;
size = (size + alignPadding) & ~alignPadding; //round up to nearest multiple of sizeof(void*), this ensures the addresses that are returned are alignment-safe.
#endif
do {
// search the heap for a free block
for (pNode = pHeap->pNext; pNode != pHeap; pNode = pNode->pNext) {
if (pNode->flags == 0 && pNode->size >= size) {
// a free block of the required size
pNode->flags = DWM_USED;
// update the LRU time
pNode->lruTime = DwGetCurrentTime() + 1;
if (pNode->size == size) {
// an exact fit
return pNode;
} else {
// allocate a node for the remainder of the free block
MEM_NODE *pTemp = AllocMemNode();
// calc size of the free block
long freeSize = pNode->size - size;
// set size of free block
pTemp->size = freeSize;
// set size of node
pNode->size = size;
// place the free node before pNode
pTemp->pBaseAddr = pNode->pBaseAddr;
pNode->pBaseAddr += freeSize;
pTemp->pNext = pNode;
pTemp->pPrev = pNode->pPrev;
pNode->pPrev->pNext = pTemp;
pNode->pPrev = pTemp;
return pNode;
}
}
}
// compact the heap if we get to here
} while (HeapCompact(size, true));
// could not allocate a block
return 0;
}
/**
* Allocate a discarded MEM_NODE. Actual memory can be assigned to it
* by using MemoryReAlloc().
*/
MEM_NODE *MemoryNoAlloc() {
MEM_NODE *pHeap = &heapSentinel;
// chain a discarded node onto the end of the heap
MEM_NODE *pNode = AllocMemNode();
pNode->flags = DWM_USED | DWM_DISCARDED;
// set mnode at the end of the list
pNode->pPrev = pHeap->pPrev;
pNode->pNext = pHeap;
// fix links to this mnode
pHeap->pPrev->pNext = pNode;
pHeap->pPrev = pNode;
// return the discarded node
return pNode;
}
/**
* Allocate a fixed block of data.
* @note For now, we simply malloc it!
* @todo We really should keep a list of the allocated pointers,
* so that we can discard them later on, when the engine quits.
*/
void *MemoryAllocFixed(long size) {
#ifdef SCUMM_NEED_ALIGNMENT
const int alignPadding = sizeof(void*) - 1;
size = (size + alignPadding) & ~alignPadding; //round up to nearest multiple of sizeof(void*), this ensures the addresses that are returned are alignment-safe.
#endif
return malloc(size);
}
/**
* Discards the specified memory object.
* @param pMemNode Node of the memory object
*/
void MemoryDiscard(MEM_NODE *pMemNode) {
// validate mnode pointer
assert(pMemNode >= mnodeList && pMemNode <= mnodeList + NUM_MNODES - 1);
// object must be in use and locked
assert((pMemNode->flags & (DWM_USED | DWM_LOCKED)) == DWM_USED);
// discard it if it isn't already
if ((pMemNode->flags & DWM_DISCARDED) == 0) {
// allocate a free node to replace this node
MEM_NODE *pTemp = AllocMemNode();
// copy node data
memcpy(pTemp, pMemNode, sizeof(MEM_NODE));
// flag as a free block
pTemp->flags = 0;
// link in the free node
pTemp->pPrev->pNext = pTemp;
pTemp->pNext->pPrev = pTemp;
// discard the node
pMemNode->flags |= DWM_DISCARDED;
pMemNode->pBaseAddr = NULL;
pMemNode->size = 0;
// and place it at the end of the heap
while ((pTemp->flags & DWM_SENTINEL) != DWM_SENTINEL)
pTemp = pTemp->pNext;
// pTemp now points to the heap sentinel
// set mnode at the end of the list
pMemNode->pPrev = pTemp->pPrev;
pMemNode->pNext = pTemp;
// fix links to this mnode
pTemp->pPrev->pNext = pMemNode;
pTemp->pPrev = pMemNode;
}
}
/**
* Locks a memory object and returns a pointer to the first byte
* of the objects memory block.
* @param pMemNode Node of the memory object
*/
void *MemoryLock(MEM_NODE *pMemNode) {
// validate mnode pointer
assert(pMemNode >= mnodeList && pMemNode <= mnodeList + NUM_MNODES - 1);
// make sure memory object is not already locked
assert((pMemNode->flags & DWM_LOCKED) == 0);
// check for a discarded or null memory object
if ((pMemNode->flags & DWM_DISCARDED) || pMemNode->size == 0)
return NULL;
// set the lock flag
pMemNode->flags |= DWM_LOCKED;
// return memory objects base address
return pMemNode->pBaseAddr;
}
/**
* Changes the size of a specified memory object and re-allocate it if necessary.
* @param pMemNode Node of the memory object
* @param size New size of block
*/
void MemoryReAlloc(MEM_NODE *pMemNode, long size) {
MEM_NODE *pNew;
// validate mnode pointer
assert(pMemNode >= mnodeList && pMemNode <= mnodeList + NUM_MNODES - 1);
// align the size to machine boundary requirements
size = (size + sizeof(void *) - 1) & ~(sizeof(void *) - 1);
// validate the size
assert(size);
if (size != pMemNode->size) {
// make sure memory object is discarded and not locked
assert(pMemNode->flags == DWM_USED | DWM_DISCARDED);
assert(pMemNode->size == 0);
// unlink the mnode from the current heap
pMemNode->pNext->pPrev = pMemNode->pPrev;
pMemNode->pPrev->pNext = pMemNode->pNext;
// allocate a new node
pNew = MemoryAlloc(size);
// make sure memory allocated
assert(pNew != NULL);
// copy the node to the current node
memcpy(pMemNode, pNew, sizeof(MEM_NODE));
// relink the mnode into the list
pMemNode->pPrev->pNext = pMemNode;
pMemNode->pNext->pPrev = pMemNode;
// free the new node
FreeMemNode(pNew);
}
}
/**
* Unlocks a memory object.
* @param pMemNode Node of the memory object
*/
void MemoryUnlock(MEM_NODE *pMemNode) {
// validate mnode pointer
assert(pMemNode >= mnodeList && pMemNode <= mnodeList + NUM_MNODES - 1);
// make sure memory object is already locked
assert(pMemNode->flags & DWM_LOCKED);
// clear the lock flag
pMemNode->flags &= ~DWM_LOCKED;
// update the LRU time
pMemNode->lruTime = DwGetCurrentTime();
}
} // End of namespace Tinsel
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