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/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.
Copyright (C) 2000-2006 Tim Angus
This file is part of Tremulous.
Tremulous 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.
Tremulous 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 Tremulous; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
===========================================================================
*/
#include "cg_local.h"
#define POOLSIZE (256 * 1024)
#define FREEMEMCOOKIE ((int)0xDEADBE3F) // Any unlikely to be used value
#define ROUNDBITS 31 // Round to 32 bytes
struct freememnode
{
// Size of ROUNDBITS
int cookie, size; // Size includes node (obviously)
struct freememnode *prev, *next;
};
static char memoryPool[ POOLSIZE ];
static struct freememnode *freehead;
static int freemem;
void *CG_Alloc( int size )
{
// Find a free block and allocate.
// Does two passes, attempts to fill same-sized free slot first.
struct freememnode *fmn, *prev, *next, *smallest;
int allocsize, smallestsize;
char *endptr;
int *ptr;
allocsize = ( size + sizeof(int) + ROUNDBITS ) & ~ROUNDBITS; // Round to 32-byte boundary
ptr = NULL;
smallest = NULL;
smallestsize = POOLSIZE + 1; // Guaranteed not to miss any slots :)
for( fmn = freehead; fmn; fmn = fmn->next )
{
if( fmn->cookie != FREEMEMCOOKIE )
CG_Error( "CG_Alloc: Memory corruption detected!\n" );
if( fmn->size >= allocsize )
{
// We've got a block
if( fmn->size == allocsize )
{
// Same size, just remove
prev = fmn->prev;
next = fmn->next;
if( prev )
prev->next = next; // Point previous node to next
if( next )
next->prev = prev; // Point next node to previous
if( fmn == freehead )
freehead = next; // Set head pointer to next
ptr = (int *) fmn;
break; // Stop the loop, this is fine
}
else
{
// Keep track of the smallest free slot
if( fmn->size < smallestsize )
{
smallest = fmn;
smallestsize = fmn->size;
}
}
}
}
if( !ptr && smallest )
{
// We found a slot big enough
smallest->size -= allocsize;
endptr = (char *) smallest + smallest->size;
ptr = (int *) endptr;
}
if( ptr )
{
freemem -= allocsize;
if( cg_debugAlloc.integer )
CG_Printf( "CG_Alloc of %i bytes (%i left)\n", allocsize, freemem );
memset( ptr, 0, allocsize );
*ptr++ = allocsize; // Store a copy of size for deallocation
return( (void *) ptr );
}
CG_Error( "CG_Alloc: failed on allocation of %i bytes\n", size );
return( NULL );
}
void CG_Free( void *ptr )
{
// Release allocated memory, add it to the free list.
struct freememnode *fmn;
char *freeend;
int *freeptr;
freeptr = ptr;
freeptr--;
freemem += *freeptr;
if( cg_debugAlloc.integer )
CG_Printf( "CG_Free of %i bytes (%i left)\n", *freeptr, freemem );
for( fmn = freehead; fmn; fmn = fmn->next )
{
freeend = ((char *) fmn) + fmn->size;
if( freeend == (char *) freeptr )
{
// Released block can be merged to an existing node
fmn->size += *freeptr; // Add size of node.
return;
}
}
// No merging, add to head of list
fmn = (struct freememnode *) freeptr;
fmn->size = *freeptr; // Set this first to avoid corrupting *freeptr
fmn->cookie = FREEMEMCOOKIE;
fmn->prev = NULL;
fmn->next = freehead;
freehead->prev = fmn;
freehead = fmn;
}
void CG_InitMemory( void )
{
// Set up the initial node
freehead = (struct freememnode *) memoryPool;
freehead->cookie = FREEMEMCOOKIE;
freehead->size = POOLSIZE;
freehead->next = NULL;
freehead->prev = NULL;
freemem = sizeof(memoryPool);
}
void CG_DefragmentMemory( void )
{
// If there's a frenzy of deallocation and we want to
// allocate something big, this is useful. Otherwise...
// not much use.
struct freememnode *startfmn, *endfmn, *fmn;
for( startfmn = freehead; startfmn; )
{
endfmn = (struct freememnode *)(((char *) startfmn) + startfmn->size);
for( fmn = freehead; fmn; )
{
if( fmn->cookie != FREEMEMCOOKIE )
CG_Error( "CG_DefragmentMemory: Memory corruption detected!\n" );
if( fmn == endfmn )
{
// We can add fmn onto startfmn.
if( fmn->prev )
fmn->prev->next = fmn->next;
if( fmn->next )
{
if( !(fmn->next->prev = fmn->prev) )
freehead = fmn->next; // We're removing the head node
}
startfmn->size += fmn->size;
memset( fmn, 0, sizeof(struct freememnode) ); // A redundant call, really.
startfmn = freehead;
endfmn = fmn = NULL; // Break out of current loop
}
else
fmn = fmn->next;
}
if( endfmn )
startfmn = startfmn->next; // endfmn acts as a 'restart' flag here
}
}
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