summaryrefslogtreecommitdiff
path: root/src/z_zone.c
blob: 2877fe6ee3ba0539697734c367029fb9e43d8cc2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
// Emacs style mode select   -*- C++ -*- 
//-----------------------------------------------------------------------------
//
// Copyright(C) 1993-1996 Id Software, Inc.
// Copyright(C) 2005 Simon Howard
//
// 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:
//	Zone Memory Allocation. Neat.
//
//-----------------------------------------------------------------------------


#include "z_zone.h"
#include "i_system.h"
#include "doomdef.h"


//
// ZONE MEMORY ALLOCATION
//
// There is never any space between memblocks,
//  and there will never be two contiguous free memblocks.
// The rover can be left pointing at a non-empty block.
//
// It is of no value to free a cachable block,
//  because it will get overwritten automatically if needed.
// 
 
#define MEM_ALIGN sizeof(void *)
#define ZONEID	0x1d4a11

typedef struct memblock_s
{
    int			size;	// including the header and possibly tiny fragments
    void**		user;
    int			tag;	// PU_FREE if this is free
    int			id;	// should be ZONEID
    struct memblock_s*	next;
    struct memblock_s*	prev;
} memblock_t;


typedef struct
{
    // total bytes malloced, including header
    int		size;

    // start / end cap for linked list
    memblock_t	blocklist;
    
    memblock_t*	rover;
    
} memzone_t;



memzone_t*	mainzone;



//
// Z_ClearZone
//
void Z_ClearZone (memzone_t* zone)
{
    memblock_t*		block;
	
    // set the entire zone to one free block
    zone->blocklist.next =
	zone->blocklist.prev =
	block = (memblock_t *)( (byte *)zone + sizeof(memzone_t) );
    
    zone->blocklist.user = (void *)zone;
    zone->blocklist.tag = PU_STATIC;
    zone->rover = block;
	
    block->prev = block->next = &zone->blocklist;
    
    // a free block.
    block->tag = PU_FREE;

    block->size = zone->size - sizeof(memzone_t);
}



//
// Z_Init
//
void Z_Init (void)
{
    memblock_t*	block;
    int		size;

    mainzone = (memzone_t *)I_ZoneBase (&size);
    mainzone->size = size;

    // set the entire zone to one free block
    mainzone->blocklist.next =
	mainzone->blocklist.prev =
	block = (memblock_t *)( (byte *)mainzone + sizeof(memzone_t) );

    mainzone->blocklist.user = (void *)mainzone;
    mainzone->blocklist.tag = PU_STATIC;
    mainzone->rover = block;
	
    block->prev = block->next = &mainzone->blocklist;

    // free block
    block->tag = PU_FREE;
    
    block->size = mainzone->size - sizeof(memzone_t);
}


//
// Z_Free
//
void Z_Free (void* ptr)
{
    memblock_t*		block;
    memblock_t*		other;
	
    block = (memblock_t *) ( (byte *)ptr - sizeof(memblock_t));

    if (block->id != ZONEID)
	I_Error ("Z_Free: freed a pointer without ZONEID");
		
    if (block->tag != PU_FREE && block->user != NULL)
    {
    	// clear the user's mark
	    *block->user = 0;
    }

    // mark as free
    block->tag = PU_FREE;
    block->user = NULL;
    block->id = 0;
	
    other = block->prev;

    if (other->tag == PU_FREE)
    {
        // merge with previous free block
        other->size += block->size;
        other->next = block->next;
        other->next->prev = other;

        if (block == mainzone->rover)
            mainzone->rover = other;

        block = other;
    }
	
    other = block->next;
    if (other->tag == PU_FREE)
    {
        // merge the next free block onto the end
        block->size += other->size;
        block->next = other->next;
        block->next->prev = block;

        if (other == mainzone->rover)
            mainzone->rover = block;
    }
}



//
// Z_Malloc
// You can pass a NULL user if the tag is < PU_PURGELEVEL.
//
#define MINFRAGMENT		64


void*
Z_Malloc
( int		size,
  int		tag,
  void*		user )
{
    int		extra;
    memblock_t*	start;
    memblock_t* rover;
    memblock_t* newblock;
    memblock_t*	base;
    void *result;

    size = (size + MEM_ALIGN - 1) & ~(MEM_ALIGN - 1);
    
    // scan through the block list,
    // looking for the first free block
    // of sufficient size,
    // throwing out any purgable blocks along the way.

    // account for size of block header
    size += sizeof(memblock_t);
    
    // if there is a free block behind the rover,
    //  back up over them
    base = mainzone->rover;
    
    if (base->prev->tag == PU_FREE)
        base = base->prev;
	
    rover = base;
    start = base->prev;
	
    do
    {
        if (rover == start)
        {
            // scanned all the way around the list
            I_Error ("Z_Malloc: failed on allocation of %i bytes", size);
        }
	
        if (rover->tag != PU_FREE)
        {
            if (rover->tag < PU_PURGELEVEL)
            {
                // hit a block that can't be purged,
                // so move base past it
                base = rover = rover->next;
            }
            else
            {
                // free the rover block (adding the size to base)

                // the rover can be the base block
                base = base->prev;
                Z_Free ((byte *)rover+sizeof(memblock_t));
                base = base->next;
                rover = base->next;
            }
        }
        else
        {
            rover = rover->next;
        }

    } while (base->tag != PU_FREE || base->size < size);

    
    // found a block big enough
    extra = base->size - size;
    
    if (extra >  MINFRAGMENT)
    {
        // there will be a free fragment after the allocated block
        newblock = (memblock_t *) ((byte *)base + size );
        newblock->size = extra;
	
        newblock->tag = PU_FREE;
        newblock->user = NULL;	
        newblock->prev = base;
        newblock->next = base->next;
        newblock->next->prev = newblock;

        base->next = newblock;
        base->size = size;
    }
	
	if (user == NULL && tag >= PU_PURGELEVEL)
	    I_Error ("Z_Malloc: an owner is required for purgable blocks");

    base->user = user;
    base->tag = tag;

    result  = (void *) ((byte *)base + sizeof(memblock_t));

    if (base->user)
    {
        *base->user = result;
    }

    // next allocation will start looking here
    mainzone->rover = base->next;	
	
    base->id = ZONEID;
    
    return result;
}



//
// Z_FreeTags
//
void
Z_FreeTags
( int		lowtag,
  int		hightag )
{
    memblock_t*	block;
    memblock_t*	next;
	
    for (block = mainzone->blocklist.next ;
	 block != &mainzone->blocklist ;
	 block = next)
    {
	// get link before freeing
	next = block->next;

	// free block?
	if (block->tag == PU_FREE)
	    continue;
	
	if (block->tag >= lowtag && block->tag <= hightag)
	    Z_Free ( (byte *)block+sizeof(memblock_t));
    }
}



//
// Z_DumpHeap
// Note: TFileDumpHeap( stdout ) ?
//
void
Z_DumpHeap
( int		lowtag,
  int		hightag )
{
    memblock_t*	block;
	
    printf ("zone size: %i  location: %p\n",
	    mainzone->size,mainzone);
    
    printf ("tag range: %i to %i\n",
	    lowtag, hightag);
	
    for (block = mainzone->blocklist.next ; ; block = block->next)
    {
	if (block->tag >= lowtag && block->tag <= hightag)
	    printf ("block:%p    size:%7i    user:%p    tag:%3i\n",
		    block, block->size, block->user, block->tag);
		
	if (block->next == &mainzone->blocklist)
	{
	    // all blocks have been hit
	    break;
	}
	
	if ( (byte *)block + block->size != (byte *)block->next)
	    printf ("ERROR: block size does not touch the next block\n");

	if ( block->next->prev != block)
	    printf ("ERROR: next block doesn't have proper back link\n");

	if (block->tag == PU_FREE && block->next->tag == PU_FREE)
	    printf ("ERROR: two consecutive free blocks\n");
    }
}


//
// Z_FileDumpHeap
//
void Z_FileDumpHeap (FILE* f)
{
    memblock_t*	block;
	
    fprintf (f,"zone size: %i  location: %p\n",mainzone->size,mainzone);
	
    for (block = mainzone->blocklist.next ; ; block = block->next)
    {
	fprintf (f,"block:%p    size:%7i    user:%p    tag:%3i\n",
		 block, block->size, block->user, block->tag);
		
	if (block->next == &mainzone->blocklist)
	{
	    // all blocks have been hit
	    break;
	}
	
	if ( (byte *)block + block->size != (byte *)block->next)
	    fprintf (f,"ERROR: block size does not touch the next block\n");

	if ( block->next->prev != block)
	    fprintf (f,"ERROR: next block doesn't have proper back link\n");

	if (block->tag == PU_FREE && block->next->tag == PU_FREE)
	    fprintf (f,"ERROR: two consecutive free blocks\n");
    }
}



//
// Z_CheckHeap
//
void Z_CheckHeap (void)
{
    memblock_t*	block;
	
    for (block = mainzone->blocklist.next ; ; block = block->next)
    {
	if (block->next == &mainzone->blocklist)
	{
	    // all blocks have been hit
	    break;
	}
	
	if ( (byte *)block + block->size != (byte *)block->next)
	    I_Error ("Z_CheckHeap: block size does not touch the next block\n");

	if ( block->next->prev != block)
	    I_Error ("Z_CheckHeap: next block doesn't have proper back link\n");

	if (block->tag == PU_FREE && block->next->tag == PU_FREE)
	    I_Error ("Z_CheckHeap: two consecutive free blocks\n");
    }
}




//
// Z_ChangeTag
//
void Z_ChangeTag2(void *ptr, int tag, char *file, int line)
{
    memblock_t*	block;
	
    block = (memblock_t *) ((byte *)ptr - sizeof(memblock_t));

    if (block->id != ZONEID)
        I_Error("%s:%i: Z_ChangeTag: block without a ZONEID!",
                file, line);

    if (tag >= PU_PURGELEVEL && block->user == NULL)
        I_Error("%s:%i: Z_ChangeTag: an owner is required "
                "for purgable blocks", file, line);

    block->tag = tag;
}



//
// Z_FreeMemory
//
int Z_FreeMemory (void)
{
    memblock_t*		block;
    int			free;
	
    free = 0;
    
    for (block = mainzone->blocklist.next ;
         block != &mainzone->blocklist;
         block = block->next)
    {
        if (block->tag == PU_FREE || block->tag >= PU_PURGELEVEL)
            free += block->size;
    }

    return free;
}

unsigned int Z_ZoneSize(void)
{
    return mainzone->size;
}