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/* Emacs style mode select -*- C++ -*-
*-----------------------------------------------------------------------------
*
*
* PrBoom a Doom port merged with LxDoom and LSDLDoom
* based on BOOM, a modified and improved DOOM engine
* Copyright (C) 1999 by
* id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
* Copyright (C) 1999-2000 by
* Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
*
* 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., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*
* DESCRIPTION:
* This is designed to be a fast allocator for small, regularly used block sizes
*-----------------------------------------------------------------------------
*/
#include "doomtype.h"
#include "z_zone.h"
#include "z_bmalloc.h"
#include "i_system.h"
#include "rockmacros.h"
typedef struct bmalpool_s {
struct bmalpool_s *nextpool;
size_t blocks;
byte used[0];
} bmalpool_t;
inline static void* getelem(bmalpool_t *p, size_t size, size_t n)
{
return (((byte*)p) + sizeof(bmalpool_t) + sizeof(byte)*(p->blocks) + size*n);
}
inline static int iselem(const bmalpool_t *pool, size_t size, const void* p)
{
// CPhipps - need portable # of bytes between pointers
int dif = (const char*)p - (const char*)pool;
dif -= sizeof(bmalpool_t);
dif -= pool->blocks;
if (dif<0) return -1;
dif /= size;
return (((size_t)dif >= pool->blocks) ? -1 : dif);
}
enum { unused_block = 0, used_block = 1};
void* Z_BMalloc(struct block_memory_alloc_s *pzone)
{
register bmalpool_t **pool = (bmalpool_t **)&(pzone->firstpool);
while (*pool != NULL) {
byte *p = memchr((*pool)->used, unused_block, (*pool)->blocks); // Scan for unused marker
if (p) {
int n = p - (*pool)->used;
#ifdef SIMPLECHECKS
if ((n<0) || ((size_t)n>=(*pool)->blocks))
I_Error("Z_BMalloc: memchr returned pointer outside of array");
#endif
(*pool)->used[n] = used_block;
return getelem(*pool, pzone->size, n);
} else
pool = &((*pool)->nextpool);
}
{
// Nothing available, must allocate a new pool
bmalpool_t *newpool;
// CPhipps: Allocate new memory, initialised to 0
*pool = newpool = Z_Calloc(sizeof(*newpool) + (sizeof(byte) + pzone->size)*(pzone->perpool),
1, pzone->tag, NULL);
newpool->nextpool = NULL; // NULL = (void*)0 so this is redundant
// Return element 0 from this pool to satisfy the request
newpool->used[0] = used_block;
newpool->blocks = pzone->perpool;
return getelem(newpool, pzone->size, 0);
}
}
void Z_BFree(struct block_memory_alloc_s *pzone, void* p)
{
register bmalpool_t **pool = (bmalpool_t**)&(pzone->firstpool);
while (*pool != NULL) {
int n = iselem(*pool, pzone->size, p);
if (n >= 0) {
#ifdef SIMPLECHECKS
if ((*pool)->used[n] == unused_block)
I_Error("Z_BFree: Refree in zone %s", pzone->desc);
#endif
(*pool)->used[n] = unused_block;
if (memchr(((*pool)->used), used_block, (*pool)->blocks) == NULL) {
// Block is all unused, can be freed
bmalpool_t *oldpool = *pool;
*pool = (*pool)->nextpool;
Z_Free(oldpool);
}
return;
} else pool = &((*pool)->nextpool);
}
I_Error("Z_BFree: Free not in zone %s", pzone->desc);
}
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