1 /* Emacs style mode select -*- C++ -*-
2 *-----------------------------------------------------------------------------
3 *
4 *
5 * PrBoom: a Doom port merged with LxDoom and LSDLDoom
6 * based on BOOM, a modified and improved DOOM engine
7 * Copyright (C) 1999 by
8 * id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
9 * Copyright (C) 1999-2000 by
10 * Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
11 * Copyright 2005, 2006 by
12 * Florian Schulze, Colin Phipps, Neil Stevens, Andrey Budko
13 *
14 * This program is free software; you can redistribute it and/or
15 * modify it under the terms of the GNU General Public License
16 * as published by the Free Software Foundation; either version 2
17 * of the License, or (at your option) any later version.
18 *
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
23 *
24 * You should have received a copy of the GNU General Public License
25 * along with this program; if not, write to the Free Software
26 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
27 * 02111-1307, USA.
28 *
29 * DESCRIPTION:
30 * This is designed to be a fast allocator for small, regularly used block sizes
31 *-----------------------------------------------------------------------------
32 */
33
34 #ifdef HAVE_CONFIG_H
35 #include "config.h"
36 #endif
37
38 #include "doomtype.h"
39 #include "z_zone.h"
40 #include "z_bmalloc.h"
41 #include "lprintf.h"
42
43 typedef struct bmalpool_s {
44 struct bmalpool_s *nextpool;
45 size_t blocks;
46 byte used[0];
47 } bmalpool_t;
48
getelem(bmalpool_t * p,size_t size,size_t n)49 inline static void* getelem(bmalpool_t *p, size_t size, size_t n)
50 {
51 return (((byte*)p) + sizeof(bmalpool_t) + sizeof(byte)*(p->blocks) + size*n);
52 }
53
iselem(const bmalpool_t * pool,size_t size,const void * p)54 inline static PUREFUNC int iselem(const bmalpool_t *pool, size_t size, const void* p)
55 {
56 // CPhipps - need portable # of bytes between pointers
57 int dif = (const char*)p - (const char*)pool;
58
59 dif -= sizeof(bmalpool_t);
60 dif -= pool->blocks;
61 if (dif<0) return -1;
62 dif /= size;
63 return (((size_t)dif >= pool->blocks) ? -1 : dif);
64 }
65
66 enum { unused_block = 0, used_block = 1};
67
Z_BMalloc(struct block_memory_alloc_s * pzone)68 void* Z_BMalloc(struct block_memory_alloc_s *pzone)
69 {
70 register bmalpool_t **pool = (bmalpool_t **)&(pzone->firstpool);
71 while (*pool != NULL) {
72 byte *p = memchr((*pool)->used, unused_block, (*pool)->blocks); // Scan for unused marker
73 if (p) {
74 int n = p - (*pool)->used;
75 #ifdef SIMPLECHECKS
76 if ((n<0) || ((size_t)n>=(*pool)->blocks))
77 I_Error("Z_BMalloc: memchr returned pointer outside of array");
78 #endif
79 (*pool)->used[n] = used_block;
80 return getelem(*pool, pzone->size, n);
81 } else
82 pool = &((*pool)->nextpool);
83 }
84 {
85 // Nothing available, must allocate a new pool
86 bmalpool_t *newpool;
87
88 // CPhipps: Allocate new memory, initialised to 0
89
90 *pool = newpool = Z_Calloc(sizeof(*newpool) + (sizeof(byte) + pzone->size)*(pzone->perpool),
91 1, pzone->tag, NULL);
92 newpool->nextpool = NULL; // NULL = (void*)0 so this is redundant
93
94 // Return element 0 from this pool to satisfy the request
95 newpool->used[0] = used_block;
96 newpool->blocks = pzone->perpool;
97 return getelem(newpool, pzone->size, 0);
98 }
99 }
100
Z_BFree(struct block_memory_alloc_s * pzone,void * p)101 void Z_BFree(struct block_memory_alloc_s *pzone, void* p)
102 {
103 register bmalpool_t **pool = (bmalpool_t**)&(pzone->firstpool);
104
105 while (*pool != NULL) {
106 int n = iselem(*pool, pzone->size, p);
107 if (n >= 0) {
108 #ifdef SIMPLECHECKS
109 if ((*pool)->used[n] == unused_block)
110 I_Error("Z_BFree: Refree in zone %s", pzone->desc);
111 #endif
112 (*pool)->used[n] = unused_block;
113 if (memchr(((*pool)->used), used_block, (*pool)->blocks) == NULL) {
114 // Block is all unused, can be freed
115 bmalpool_t *oldpool = *pool;
116 *pool = (*pool)->nextpool;
117 Z_Free(oldpool);
118 }
119 return;
120 } else pool = &((*pool)->nextpool);
121 }
122 I_Error("Z_BFree: Free not in zone %s", pzone->desc);
123 }
124