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580 lines
17 KiB
C++
580 lines
17 KiB
C++
/* Copyright (C) 1994-2003 Revolution Software Ltd
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* $Header$
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*/
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// FIXME: We should investigate which problem all this memory managing stuff
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// is trying to solve. I'm not convinced that it's really needed.
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// memory manager
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// - "remember, it's not good to leave memory locked for a moment longer
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// than necessary" Tony
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// - "actually, in a sequential system theoretically you never need to lock
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// any memory!" Chris ;)
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//
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// This is a very simple implementation but I see little advantage to being
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// any cleverer with the coding - i could have put the mem blocks before the
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// defined blocks instead of in an array and then used pointers to
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// child/parent blocks. But why bother? I've Kept it simple. When it needs
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// updating or customising it will be accessable to anyone who looks at it.
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//
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// Doesn't have a purgeable/age consituant yet - if anyone wants this then
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// I'll add it in.
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// MemMan v1.1
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#include "stdafx.h"
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#include "debug.h"
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#include "memory.h"
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#include "resman.h"
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uint32 total_blocks;
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uint32 total_free_memory;
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#define MEMORY_POOL (1024 * 12000)
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// address of init malloc to be freed later
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uint8 *free_memman;
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// list of defined memory handles - each representing a block of memory.
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mem mem_list[MAX_mem_blocks];
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uint32 base_mem_block;
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// #define MEMDEBUG 1
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// Used to determine if the required size can be obtained if the defragger is
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// allowed to run.
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int32 VirtualDefrag(uint32 size);
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// Start position of the Defragger as indicated by its sister VirtualDefrag.
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int32 suggestedStart = 0;
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void Close_memory_manager(void) { // Tony2Oct96
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free(free_memman);
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}
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void Init_memory_manager(void) { // Tony9April96
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uint32 j;
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uint8 *memory_base;
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total_free_memory = MEMORY_POOL;
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// malloc memory and adjust for long boundaries
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memory_base = (uint8 *) malloc(total_free_memory);
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if (!memory_base) { //could not grab the memory
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Zdebug("couldn't malloc %d in Init_memory_manager", total_free_memory);
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ExitWithReport("Init_memory_manager() couldn't malloc %d bytes [line=%d file=%s]", total_free_memory, __LINE__, __FILE__);
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}
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// the original malloc address
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free_memman = memory_base;
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#if 0
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// FIXME: I don't think it's necessary to force alignment here,
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// because memory_base is the address returned by malloc(), and
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// according to my C book "every allocated region from malloc must
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// be aligned for any type".
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// force to long word boundary
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memory_base += 3;
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memory_base = (uint8 *) ((uint32) memory_base & 0xfffffffc); // ** was (int)memory_base
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// total_free_memory -= 3; //play safe
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#endif
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// set all but first handle to unused
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for (j = 1; j < MAX_mem_blocks; j++)
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mem_list[j].state = MEM_null;
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// total used (free, locked or floating)
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total_blocks = 1;
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mem_list[0].ad = memory_base;
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mem_list[0].state = MEM_free;
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mem_list[0].age = 0;
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mem_list[0].size = total_free_memory;
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mem_list[0].parent = -1; // we are base - for now
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mem_list[0].child = -1; // we are the end as well
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mem_list[0].uid = UID_memman; // init id
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base_mem_block = 0; // for now
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}
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// This is the low-level memory allocator
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mem *Talloc(uint32 size, uint32 type, uint32 unique_id) { // Tony10Apr96
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// allocate a block of memory - locked or float
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// returns 0 if fails to allocate the memory
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// or a pointer to a mem structure
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int32 nu_block;
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uint32 spawn = 0;
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uint32 slack;
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// we must first round the size UP to a dword, so subsequent blocks
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// will start dword alligned
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size += 3; // move up
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size &= 0xfffffffc; // and back down to boundary
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// find a free block large enough
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// the defragger returns when its made a big enough block. This is
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// a good time to defrag as we're probably not doing anything super
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// time-critical at the moment
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if ((nu_block = Defrag_mem(size)) == -1) {
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// error - couldn't find a big enough space
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return 0;
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}
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// an exact fit?
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if (mem_list[nu_block].size == size) {
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// no new block is required as the fit is perfect
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mem_list[nu_block].state = type; // locked or float
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mem_list[nu_block].size = size; // set to the required size
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mem_list[nu_block].uid = unique_id; // an identifier
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#ifdef MEMDEBUG
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Mem_debug();
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#endif
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return &mem_list[nu_block];
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}
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// nu_block is the free block to split, forming our locked/float block
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// with a new free block in any remaining space
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// If our child is free then is can expand downwards to eat up our
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// chopped space this is good because it doesn't create an extra block
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// so keeping the block count down.
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//
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// Why? Imagine you Talloc 1000k, then free it. Now keep allocating 10
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// bytes less and freeing again you end up with thousands of new free
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// mini blocks. This way avoids that as the free child keeps growing
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// downwards.
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if (mem_list[nu_block].child != -1 && mem_list[mem_list[nu_block].child].state == MEM_free) {
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// our child is free
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// the spare memory is the blocks current size minus the
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// amount we're taking
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slack = mem_list[nu_block].size - size;
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mem_list[nu_block].state = type; // locked or float
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mem_list[nu_block].size = size; // set to the required size
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mem_list[nu_block].uid = unique_id; // an identifier
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// child starts after us
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mem_list[mem_list[nu_block].child].ad = mem_list[nu_block].ad + size;
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// child's size increases
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mem_list[mem_list[nu_block].child].size += slack;
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return &mem_list[nu_block];
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}
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// otherwise we spawn a new block after us and before our child - our
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// child being a proper block that we cannot change
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// we remain a child of our parent
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// we spawn a new child and it inherits our current child
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// find a NULL slot for a new block
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while (mem_list[spawn].state != MEM_null && spawn!=MAX_mem_blocks)
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spawn++;
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if (spawn == MAX_mem_blocks) {
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// run out of blocks - stop the program. this is a major blow
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// up and we need to alert the developer
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// Lets get a printout of this
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Mem_debug();
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ExitWithReport("ERROR: ran out of mem blocks in Talloc() [file=%s line=%u]", __FILE__, __LINE__);
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}
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mem_list[spawn].state = MEM_free; // new block is free
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mem_list[spawn].uid = UID_memman; // a memman created bloc
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// size of the existing parent free block minus the size of the new
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// space Talloc'ed.
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mem_list[spawn].size = mem_list[nu_block].size - size;
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// IOW the remaining memory is given to the new free block
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// we start 1 byte after the newly allocated block
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mem_list[spawn].ad = mem_list[nu_block].ad + size;
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// the spawned child gets it parent - the newly allocated block
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mem_list[spawn].parent = nu_block;
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// the new child inherits the parents old child (we are its new
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// child "Waaaa")
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mem_list[spawn].child = mem_list[nu_block].child;
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// is the spawn the end block?
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if (mem_list[spawn].child != -1) {
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// the child of the new free-spawn needs to know its new parent
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mem_list[mem_list[spawn].child].parent = spawn;
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}
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mem_list[nu_block].state = type; // locked or float
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mem_list[nu_block].size = size; // set to the required size
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mem_list[nu_block].uid = unique_id; // an identifier
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// the new blocks new child is the newly formed free block
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mem_list[nu_block].child = spawn;
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//we've brought a new block into the world. Ahhh!
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total_blocks++;
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#ifdef MEMDEBUG
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Mem_debug();
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#endif
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return &mem_list[nu_block];
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}
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void Free_mem(mem *block) { // Tony10Apr96
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// kill a block of memory - which was presumably floating or locked
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// once you've done this the memory may be recycled
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block->state = MEM_free;
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block->uid = UID_memman; // belongs to the memory manager again
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#ifdef MEMDEBUG
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Mem_debug();
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#endif
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}
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void Float_mem(mem *block) { // Tony10Apr96
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// set a block to float
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// wont be trashed but will move around in memory
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block->state = MEM_float;
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#ifdef MEMDEBUG
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Mem_debug();
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#endif
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}
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void Lock_mem(mem *block) { // Tony11Apr96
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// set a block to lock
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// wont be moved - don't lock memory for any longer than necessary
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// unless you know the locked memory is at the bottom of the heap
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// can't move now - this block is now crying out to be floated or
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// free'd again
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block->state = MEM_locked;
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#ifdef MEMDEBUG
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Mem_debug();
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#endif
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}
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int32 Defrag_mem(uint32 req_size) { // Tony10Apr96
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// moves floating blocks down and/or merges free blocks until a large
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// enough space is found or there is nothing left to do and a big
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// enough block cannot be found we stop when we find/create a large
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// enough block - this is enough defragging.
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int32 cur_block; // block 0 remains the parent block
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int32 original_parent,child, end_child;
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uint32 j;
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uint32 *a;
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uint32 *b;
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// cur_block = base_mem_block; //the mother of all parents
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cur_block = suggestedStart;
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do {
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// is current block a free block?
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if (mem_list[cur_block].state == MEM_free) {
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if (mem_list[cur_block].size >= req_size) {
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// this block is big enough - return its id
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return cur_block;
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}
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// the child is the end block - stop if the next block
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// along is the end block
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if (mem_list[cur_block].child == -1) {
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// no luck, couldn't find a big enough block
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return -1;
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}
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// current free block is too small, but if its child
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// is *also* free then merge the two together
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if (mem_list[mem_list[cur_block].child].state == MEM_free) {
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// ok, we nuke the child and inherit its child
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child = mem_list[cur_block].child;
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// our size grows by the size of our child
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mem_list[cur_block].size += mem_list[child].size;
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// our new child is our old childs, child
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mem_list[cur_block].child = mem_list[child].child;
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// not if the chld we're nuking is the end
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// child (it has no child)
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if (mem_list[child].child != -1) {
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// the (nuked) old childs childs
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// parent is now us
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mem_list[mem_list[child].child].parent = cur_block;
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}
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// clean up the nuked child, so it can be used
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// again
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mem_list[child].state = MEM_null;
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total_blocks--;
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} else if (mem_list[mem_list[cur_block].child].state == MEM_float) {
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// current free block is too small, but if its
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// child is a float then we move the floating
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// memory block down and the free up but,
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// parent/child relationships must be such
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// that the memory is all continuous between
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// blocks. ie. a childs memory always begins 1
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// byte after its parent finishes. However, the
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// positions in the memory list may become
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// truly random, but, any particular block of
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// locked or floating memory must retain its
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// position within the mem_list - the float
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// stays a float because the handle/pointer
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// has been passed back
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//
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// what this means is that when the physical
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// memory of the foat moves down (and the free
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// up) the child becomes the parent and the
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// parent the child but, remember, the parent
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// had a parent and the child another child -
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// these swap over too as the parent/child swap
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// takes place - phew.
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// our child is currently floating
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child = mem_list[cur_block].child;
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// move the higher float down over the free
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// block
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// memcpy(mem_list[cur_block].ad, mem_list[child].ad, mem_list[child].size);
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a = (uint32*) mem_list[cur_block].ad;
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b = (uint32*) mem_list[child].ad;
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for (j = 0; j < mem_list[child].size / 4; j++)
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*(a++) = *(b++);
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// both *ad's change
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// the float is now where the free was and the
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// free goes up by the size of the float
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// (which has come down)
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mem_list[child].ad = mem_list[cur_block].ad;
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mem_list[cur_block].ad += mem_list[child].size;
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// the status of the mem_list blocks must
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// remain the same, so...
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// our child gets this when we become its
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// child and it our parent
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original_parent = mem_list[cur_block].parent;
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// the free's child becomes its parent
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mem_list[cur_block].parent = child;
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// the new child inherits its previous childs
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// child
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mem_list[cur_block].child = mem_list[child].child;
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// save this - see next line
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end_child = mem_list[child].child;
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// the floats parent becomes its child
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mem_list[child].child = cur_block;
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mem_list[child].parent = original_parent;
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// if the child had a child
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if (end_child != -1) {
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// then its parent is now the new child
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mem_list[end_child].parent = cur_block;
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}
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// if the base block was the true base parent
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if (original_parent == -1) {
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// then the child that has moved down
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// becomes the base block as it sits
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// at the lowest possible memory
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// location
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base_mem_block = child;
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} else {
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// otherwise the parent of the current
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// free block - that is now the child
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// - gets a new child, that child
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// being previously the child of the
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// child of the original parent
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mem_list[original_parent].child = child;
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}
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} else { // if (mem_list[mem_list[cur_block].child].state == MEM_lock)
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// the child of current is locked - move to it
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// move to next one along - either locked or
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// END
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cur_block=mem_list[cur_block].child;
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}
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} else {
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// move to next one along, the current must be
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// floating, locked, or a NULL slot
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cur_block = mem_list[cur_block].child;
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}
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} while (cur_block != -1); // while the block we've just done is not the final block
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return -1; //no luck, couldn't find a big enough block
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}
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void Mem_debug(void) { //Tony11Apr96
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// gets called with Talloc, Mem_free, Mem_lock & Mem_float if
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// MEMDEBUG has been #defined otherwise can be called at any time
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// anywhere else
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int j;
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char inf[][20] = {
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{ "MEM_null" },
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{ "MEM_free" },
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{ "MEM_locked" },
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{ "MEM_float" }
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};
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Zdebug("\nbase %d total %d", base_mem_block, total_blocks);
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// first in mem list order
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for (j = 0; j < MAX_mem_blocks; j++) {
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if (mem_list[j].state == MEM_null)
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Zdebug("%d- NULL", j);
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else
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Zdebug("%d- state %s, ad %d, size %d, p %d, c %d, id %d",
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j, inf[mem_list[j].state], mem_list[j].ad,
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mem_list[j].size, mem_list[j].parent,
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mem_list[j].child, mem_list[j].uid);
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}
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// now in child/parent order
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j = base_mem_block;
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do {
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Zdebug(" %d- state %s, ad %d, size %d, p %d, c %d", j,
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inf[mem_list[j].state], mem_list[j].ad,
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mem_list[j].size, mem_list[j].parent,
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mem_list[j].child, mem_list[j].uid);
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j = mem_list[j].child;
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} while (j != -1);
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}
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mem *Twalloc(uint32 size, uint32 type, uint32 unique_id) { // tony12Feb97
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// the high level Talloc
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// can ask the resman to remove old resources to make space - will
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// either do it or halt the system
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mem *membloc;
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int j;
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uint32 free = 0;
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while (VirtualDefrag(size)) {
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// trash the oldest closed resource
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if (!res_man.Help_the_aged_out()) {
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Zdebug("Twalloc ran out of memory! %d %d %d\n", size, type, unique_id);
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ExitWithReport("Twalloc ran out of memory!");
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}
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}
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membloc = Talloc(size, type, unique_id);
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if (membloc == 0) {
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Zdebug("Talloc failed to get memory VirtualDefrag said was there");
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ExitWithReport("Talloc failed to get memory VirtualDefrag said was there");
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}
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j = base_mem_block;
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do {
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if (mem_list[j].state == MEM_free)
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|
free += mem_list[j].size;
|
|
|
|
j = mem_list[j].child;
|
|
} while (j != -1);
|
|
|
|
// return the pointer to the memory
|
|
return membloc;
|
|
}
|
|
|
|
// Maximum allowed wasted memory.
|
|
#define MAX_WASTAGE 51200
|
|
|
|
int32 VirtualDefrag(uint32 size) { // Chris - 07 April '97
|
|
// Virutually defrags memory...
|
|
//
|
|
// Used to determine if there is potentially are large enough free
|
|
// block available is the real defragger was allowed to run.
|
|
//
|
|
// The idea being that Twalloc will call this and help_the_aged_out
|
|
// until we indicate that it is possible to obtain a large enough
|
|
// free block. This way the defragger need only run once to yield the
|
|
// required block size.
|
|
//
|
|
// The reason for its current slowness is that the defragger is
|
|
// potentially called several times, each time shifting upto 20Megs
|
|
// around, to obtain the required free block.
|
|
|
|
int32 cur_block;
|
|
uint32 currentBubbleSize = 0;
|
|
|
|
cur_block = base_mem_block;
|
|
suggestedStart = base_mem_block;
|
|
|
|
do {
|
|
if (mem_list[cur_block].state == MEM_free) {
|
|
// Add a little intelligence. At the start the oldest
|
|
// resources are at the bottom of the tube. However
|
|
// there will be some air at the top. Thus bubbles
|
|
// will be created at the bottom and float to the
|
|
// top. If we ignore the top gap then a large enough
|
|
// bubble will form lower down the tube. Thus less
|
|
// memory will need to be shifted.
|
|
|
|
if (mem_list[cur_block].child != -1)
|
|
currentBubbleSize += mem_list[cur_block].size;
|
|
else if (mem_list[cur_block].size > MAX_WASTAGE)
|
|
currentBubbleSize += mem_list[cur_block].size;
|
|
|
|
if (currentBubbleSize >= size)
|
|
return 0;
|
|
} else if (mem_list[cur_block].state == MEM_locked) {
|
|
currentBubbleSize = 0;
|
|
// Any free block of the correct size will be above
|
|
// this locked block.
|
|
suggestedStart = mem_list[cur_block].child;
|
|
}
|
|
|
|
cur_block = mem_list[cur_block].child;
|
|
} while (cur_block != -1);
|
|
|
|
return 1;
|
|
}
|