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 #include "config.h"
35
36 #include "doomtype.h"
37 #include "z_zone.h"
38 #include "z_bmalloc.h"
39 #include "lprintf.h"
40
41 typedef struct bmalpool_s {
42 struct bmalpool_s *nextpool;
43 size_t blocks;
44 uint8_t used[0];
45 } bmalpool_t;
46
getelem(bmalpool_t * p,size_t size,size_t n)47 static INLINE void* getelem(bmalpool_t *p, size_t size, size_t n)
48 {
49 return (((uint8_t*)p) + sizeof(bmalpool_t) + sizeof(uint8_t)*(p->blocks) + size*n);
50 }
51
iselem(const bmalpool_t * pool,size_t size,const void * p)52 static INLINE int iselem(const bmalpool_t *pool, size_t size, const void* p)
53 {
54 // CPhipps - need portable # of bytes between pointers
55 int dif = (const char*)p - (const char*)pool;
56
57 dif -= sizeof(bmalpool_t);
58 dif -= pool->blocks;
59 if (dif<0) return -1;
60 dif /= size;
61 return (((size_t)dif >= pool->blocks) ? -1 : dif);
62 }
63
64 enum { unused_block = 0, used_block = 1};
65
Z_BMalloc(struct block_memory_alloc_s * pzone)66 void* Z_BMalloc(struct block_memory_alloc_s *pzone)
67 {
68 register bmalpool_t **pool = (bmalpool_t **)&(pzone->firstpool);
69 while (*pool != NULL)
70 {
71 uint8_t *p = memchr((*pool)->used, unused_block, (*pool)->blocks); // Scan for unused marker
72 if (p) {
73 int n = p - (*pool)->used;
74 (*pool)->used[n] = used_block;
75 return getelem(*pool, pzone->size, n);
76 } else
77 pool = &((*pool)->nextpool);
78 }
79
80 {
81 // Nothing available, must allocate a new pool
82 bmalpool_t *newpool;
83
84 // CPhipps: Allocate new memory, initialised to 0
85
86 *pool = newpool = Z_Calloc(sizeof(*newpool) + (sizeof(uint8_t) + pzone->size)*(pzone->perpool),
87 1, pzone->tag, NULL);
88 newpool->nextpool = NULL; // NULL = (void*)0 so this is redundant
89
90 // Return element 0 from this pool to satisfy the request
91 newpool->used[0] = used_block;
92 newpool->blocks = pzone->perpool;
93 return getelem(newpool, pzone->size, 0);
94 }
95 }
96
Z_BFree(struct block_memory_alloc_s * pzone,void * p)97 void Z_BFree(struct block_memory_alloc_s *pzone, void* p)
98 {
99 register bmalpool_t **pool = (bmalpool_t**)&(pzone->firstpool);
100
101 while (*pool != NULL) {
102 int n = iselem(*pool, pzone->size, p);
103 if (n >= 0) {
104 (*pool)->used[n] = unused_block;
105 if (memchr(((*pool)->used), used_block, (*pool)->blocks) == NULL) {
106 // Block is all unused, can be freed
107 bmalpool_t *oldpool = *pool;
108 *pool = (*pool)->nextpool;
109 Z_Free(oldpool);
110 }
111 return;
112 } else pool = &((*pool)->nextpool);
113 }
114 I_Error("Z_BFree: Free not in zone %s", pzone->desc);
115 }
116