xref: /dragonfly/sys/kern/subr_alist.c (revision 36a3d1d6)
1 /*
2  * ALIST.C -	Bitmap allocator/deallocator, using a radix tree with hinting.
3  *		Unlimited-size allocations, power-of-2 only, power-of-2
4  *		aligned results only.
5  *
6  * Copyright (c) 2007 The DragonFly Project.  All rights reserved.
7  *
8  * This code is derived from software contributed to The DragonFly Project
9  * by Matthew Dillon <dillon@backplane.com>
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  *
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in
19  *    the documentation and/or other materials provided with the
20  *    distribution.
21  * 3. Neither the name of The DragonFly Project nor the names of its
22  *    contributors may be used to endorse or promote products derived
23  *    from this software without specific, prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
28  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
29  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
30  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
31  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
32  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
33  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
34  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
35  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  *
38  * $DragonFly: src/sys/kern/subr_alist.c,v 1.4 2008/04/23 17:21:08 dillon Exp $
39  */
40 /*
41  * This module has been adapted from the BLIST module, which was written
42  * by Matthew Dillon many years ago.
43  *
44  * This module implements a general power-of-2 bitmap allocator/deallocator.
45  * All allocations must be in powers of 2 and will return similarly aligned
46  * results.  The module does not try to interpret the meaning of a 'block'
47  * other then to return ALIST_BLOCK_NONE on an allocation failure.
48  *
49  * A maximum of 2 billion blocks is supported so, for example, if one block
50  * represented 64 bytes a maximally sized ALIST would represent
51  * 128 gigabytes.
52  *
53  * A radix tree is used to maintain the bitmap and layed out in a manner
54  * similar to the blist code.  Meta nodes use a radix of 16 and 2 bits per
55  * block while leaf nodes use a radix of 32 and 1 bit per block (stored in
56  * a 32 bit bitmap field).  Both meta and leaf nodes have a hint field.
57  * This field gives us a hint as to the largest free contiguous range of
58  * blocks under the node.  It may contain a value that is too high, but
59  * will never contain a value that is too low.  When the radix tree is
60  * searched, allocation failures in subtrees update the hint.
61  *
62  * The radix tree is layed out recursively using a linear array.  Each meta
63  * node is immediately followed (layed out sequentially in memory) by
64  * ALIST_META_RADIX lower level nodes.  This is a recursive structure but one
65  * that can be easily scanned through a very simple 'skip' calculation.  In
66  * order to support large radixes, portions of the tree may reside outside our
67  * memory allocation.  We handle this with an early-terminate optimization
68  * in the meta-node.  The memory allocation is only large enough to cover
69  * the number of blocks requested at creation time even if it must be
70  * encompassed in larger root-node radix.
71  *
72  * This code can be compiled stand-alone for debugging.
73  */
74 
75 #ifdef _KERNEL
76 
77 #include <sys/param.h>
78 #include <sys/systm.h>
79 #include <sys/lock.h>
80 #include <sys/kernel.h>
81 #include <sys/alist.h>
82 #include <sys/malloc.h>
83 #include <vm/vm.h>
84 #include <vm/vm_object.h>
85 #include <vm/vm_kern.h>
86 #include <vm/vm_extern.h>
87 #include <vm/vm_page.h>
88 
89 #else
90 
91 #ifndef ALIST_NO_DEBUG
92 #define ALIST_DEBUG
93 #endif
94 
95 #include <sys/types.h>
96 #include <stdio.h>
97 #include <assert.h>
98 #include <string.h>
99 #include <stdlib.h>
100 #include <stdarg.h>
101 
102 #define kmalloc(a,b,c)	malloc(a)
103 #define kfree(a,b)	free(a)
104 #define kprintf		printf
105 #define KKASSERT(exp)	assert(exp)
106 struct malloc_type;
107 
108 typedef unsigned int u_daddr_t;
109 
110 #include <sys/alist.h>
111 
112 void panic(const char *ctl, ...);
113 
114 #endif
115 
116 /*
117  * static support functions
118  */
119 
120 static daddr_t alst_leaf_alloc(almeta_t *scan, daddr_t blk, int count);
121 static daddr_t alst_meta_alloc(almeta_t *scan, daddr_t blk,
122 				daddr_t count, daddr_t radix, int skip);
123 static void alst_leaf_free(almeta_t *scan, daddr_t relblk, int count);
124 static void alst_meta_free(almeta_t *scan, daddr_t freeBlk, daddr_t count,
125 					daddr_t radix, int skip, daddr_t blk);
126 static daddr_t	alst_radix_init(almeta_t *scan, daddr_t radix,
127 						int skip, daddr_t count);
128 #ifndef _KERNEL
129 static void	alst_radix_print(almeta_t *scan, daddr_t blk,
130 					daddr_t radix, int skip, int tab);
131 #endif
132 
133 /*
134  * alist_create() - create a alist capable of handling up to the specified
135  *		    number of blocks
136  *
137  *	blocks must be greater then 0
138  *
139  *	The smallest alist consists of a single leaf node capable of
140  *	managing ALIST_BMAP_RADIX blocks.
141  */
142 
143 alist_t
144 alist_create(daddr_t blocks, struct malloc_type *mtype)
145 {
146 	alist_t bl;
147 	int radix;
148 	int skip = 0;
149 
150 	/*
151 	 * Calculate radix and skip field used for scanning.
152 	 */
153 	radix = ALIST_BMAP_RADIX;
154 
155 	while (radix < blocks) {
156 		radix *= ALIST_META_RADIX;
157 		skip = (skip + 1) * ALIST_META_RADIX;
158 	}
159 
160 	bl = kmalloc(sizeof(struct alist), mtype, M_WAITOK);
161 
162 	bzero(bl, sizeof(*bl));
163 
164 	bl->bl_blocks = blocks;
165 	bl->bl_radix = radix;
166 	bl->bl_skip = skip;
167 	bl->bl_rootblks = 1 +
168 	    alst_radix_init(NULL, bl->bl_radix, bl->bl_skip, blocks);
169 	bl->bl_root = kmalloc(sizeof(almeta_t) * bl->bl_rootblks, mtype, M_WAITOK);
170 
171 #if defined(ALIST_DEBUG)
172 	kprintf(
173 		"ALIST representing %d blocks (%d MB of swap)"
174 		", requiring %dK (%d bytes) of ram\n",
175 		bl->bl_blocks,
176 		bl->bl_blocks * 4 / 1024,
177 		(bl->bl_rootblks * sizeof(almeta_t) + 1023) / 1024,
178 		(bl->bl_rootblks * sizeof(almeta_t))
179 	);
180 	kprintf("ALIST raw radix tree contains %d records\n", bl->bl_rootblks);
181 #endif
182 	alst_radix_init(bl->bl_root, bl->bl_radix, bl->bl_skip, blocks);
183 
184 	return(bl);
185 }
186 
187 void
188 alist_destroy(alist_t bl, struct malloc_type *mtype)
189 {
190 	kfree(bl->bl_root, mtype);
191 	kfree(bl, mtype);
192 }
193 
194 /*
195  * alist_alloc() - reserve space in the block bitmap.  Return the base
196  *		   of a contiguous region or ALIST_BLOCK_NONE if space
197  *		   could not be allocated.
198  */
199 
200 daddr_t
201 alist_alloc(alist_t bl, daddr_t count)
202 {
203 	daddr_t blk = ALIST_BLOCK_NONE;
204 
205 	KKASSERT((count | (count - 1)) == (count << 1) - 1);
206 
207 	if (bl && count < bl->bl_radix) {
208 		if (bl->bl_radix == ALIST_BMAP_RADIX)
209 			blk = alst_leaf_alloc(bl->bl_root, 0, count);
210 		else
211 			blk = alst_meta_alloc(bl->bl_root, 0, count, bl->bl_radix, bl->bl_skip);
212 		if (blk != ALIST_BLOCK_NONE)
213 			bl->bl_free -= count;
214 	}
215 	return(blk);
216 }
217 
218 /*
219  * alist_free() -	free up space in the block bitmap.  Return the base
220  *		     	of a contiguous region.  Panic if an inconsistancy is
221  *			found.
222  */
223 
224 void
225 alist_free(alist_t bl, daddr_t blkno, daddr_t count)
226 {
227 	if (bl) {
228 		KKASSERT(blkno + count <= bl->bl_blocks);
229 		if (bl->bl_radix == ALIST_BMAP_RADIX)
230 			alst_leaf_free(bl->bl_root, blkno, count);
231 		else
232 			alst_meta_free(bl->bl_root, blkno, count, bl->bl_radix, bl->bl_skip, 0);
233 		bl->bl_free += count;
234 	}
235 }
236 
237 #ifdef ALIST_DEBUG
238 
239 /*
240  * alist_print()    - dump radix tree
241  */
242 
243 void
244 alist_print(alist_t bl)
245 {
246 	kprintf("ALIST {\n");
247 	alst_radix_print(bl->bl_root, 0, bl->bl_radix, bl->bl_skip, 4);
248 	kprintf("}\n");
249 }
250 
251 #endif
252 
253 /************************************************************************
254  *			  ALLOCATION SUPPORT FUNCTIONS			*
255  ************************************************************************
256  *
257  *	These support functions do all the actual work.  They may seem
258  *	rather longish, but that's because I've commented them up.  The
259  *	actual code is straight forward.
260  *
261  */
262 
263 /*
264  * alist_leaf_alloc() -	allocate at a leaf in the radix tree (a bitmap).
265  *
266  *	This is the core of the allocator and is optimized for the 1 block
267  *	and the ALIST_BMAP_RADIX block allocation cases.  Other cases are
268  *	somewhat slower.  The 1 block allocation case is log2 and extremely
269  *	quick.
270  */
271 
272 static daddr_t
273 alst_leaf_alloc(
274 	almeta_t *scan,
275 	daddr_t blk,
276 	int count
277 ) {
278 	u_daddr_t orig = scan->bm_bitmap;
279 
280 	/*
281 	 * Optimize bitmap all-allocated case.  Also, count = 1
282 	 * case assumes at least 1 bit is free in the bitmap, so
283 	 * we have to take care of this case here.
284 	 */
285 	if (orig == 0) {
286 		scan->bm_bighint = 0;
287 		return(ALIST_BLOCK_NONE);
288 	}
289 
290 	/*
291 	 * Optimized code to allocate one bit out of the bitmap
292 	 */
293 	if (count == 1) {
294 		u_daddr_t mask;
295 		int j = ALIST_BMAP_RADIX/2;
296 		int r = 0;
297 
298 		mask = (u_daddr_t)-1 >> (ALIST_BMAP_RADIX/2);
299 
300 		while (j) {
301 			if ((orig & mask) == 0) {
302 			    r += j;
303 			    orig >>= j;
304 			}
305 			j >>= 1;
306 			mask >>= j;
307 		}
308 		scan->bm_bitmap &= ~(1 << r);
309 		return(blk + r);
310 	}
311 
312 	/*
313 	 * non-optimized code to allocate N bits out of the bitmap.
314 	 * The more bits, the faster the code runs.  It will run
315 	 * the slowest allocating 2 bits, but since there aren't any
316 	 * memory ops in the core loop (or shouldn't be, anyway),
317 	 * you probably won't notice the difference.
318 	 *
319 	 * Similar to the blist case, the alist code also requires
320 	 * allocations to be power-of-2 sized and aligned to the
321 	 * size of the allocation, which simplifies the algorithm.
322 	 */
323 	{
324 		int j;
325 		int n = ALIST_BMAP_RADIX - count;
326 		u_daddr_t mask;
327 
328 		mask = (u_daddr_t)-1 >> n;
329 
330 		for (j = 0; j <= n; j += count) {
331 			if ((orig & mask) == mask) {
332 				scan->bm_bitmap &= ~mask;
333 				return(blk + j);
334 			}
335 			mask = mask << count;
336 		}
337 	}
338 
339 	/*
340 	 * We couldn't allocate count in this subtree, update bighint.
341 	 */
342 	scan->bm_bighint = count - 1;
343 	return(ALIST_BLOCK_NONE);
344 }
345 
346 /*
347  * alist_meta_alloc() -	allocate at a meta in the radix tree.
348  *
349  *	Attempt to allocate at a meta node.  If we can't, we update
350  *	bighint and return a failure.  Updating bighint optimize future
351  *	calls that hit this node.  We have to check for our collapse cases
352  *	and we have a few optimizations strewn in as well.
353  */
354 
355 static daddr_t
356 alst_meta_alloc(
357 	almeta_t *scan,
358 	daddr_t blk,
359 	daddr_t count,
360 	daddr_t radix,
361 	int skip
362 ) {
363 	int i;
364 	u_daddr_t mask;
365 	u_daddr_t pmask;
366 	int next_skip = ((u_int)skip / ALIST_META_RADIX);
367 
368 	/*
369 	 * ALL-ALLOCATED special case
370 	 */
371 	if (scan->bm_bitmap == 0)  {
372 		scan->bm_bighint = 0;
373 		return(ALIST_BLOCK_NONE);
374 	}
375 
376 	radix /= ALIST_META_RADIX;
377 
378 	/*
379 	 * Radix now represents each bitmap entry for this meta node.  If
380 	 * the number of blocks being allocated can be fully represented,
381 	 * we allocate directly out of this meta node.
382 	 *
383 	 * Meta node bitmaps use 2 bits per block.
384 	 *
385 	 *	00	ALL-ALLOCATED
386 	 *	01	PARTIALLY-FREE/PARTIALLY-ALLOCATED
387 	 *	10	(RESERVED)
388 	 *	11	ALL-FREE
389 	 */
390 	if (count >= radix) {
391 		int n = count / radix * 2;	/* number of bits */
392 		int j;
393 
394 		mask = (u_daddr_t)-1 >> (ALIST_BMAP_RADIX - n);
395 		for (j = 0; j < ALIST_META_RADIX; j += n / 2) {
396 			if ((scan->bm_bitmap & mask) == mask) {
397 				scan->bm_bitmap &= ~mask;
398 				return(blk + j * radix);
399 			}
400 			mask <<= n;
401 		}
402 		if (scan->bm_bighint >= count)
403 			scan->bm_bighint = count >> 1;
404 		return(ALIST_BLOCK_NONE);
405 	}
406 
407 	/*
408 	 * If not we have to recurse.
409 	 */
410 	mask = 0x00000003;
411 	pmask = 0x00000001;
412 	for (i = 1; i <= skip; i += next_skip) {
413 		if (scan[i].bm_bighint == (daddr_t)-1) {
414 			/*
415 			 * Terminator
416 			 */
417 			break;
418 		}
419 
420 		/*
421 		 * If the element is marked completely free (11), initialize
422 		 * the recursion.
423 		 */
424 		if ((scan->bm_bitmap & mask) == mask) {
425 			scan[i].bm_bitmap = (u_daddr_t)-1;
426 			scan[i].bm_bighint = radix;
427 		}
428 
429 		if ((scan->bm_bitmap & mask) == 0) {
430 			/*
431 			 * Object marked completely allocated, recursion
432 			 * contains garbage.
433 			 */
434 			/* Skip it */
435 		} else if (count <= scan[i].bm_bighint) {
436 			/*
437 			 * count fits in object
438 			 */
439 			daddr_t r;
440 			if (next_skip == 1) {
441 				r = alst_leaf_alloc(&scan[i], blk, count);
442 			} else {
443 				r = alst_meta_alloc(&scan[i], blk, count, radix, next_skip - 1);
444 			}
445 			if (r != ALIST_BLOCK_NONE) {
446 				if (scan[i].bm_bitmap == 0) {
447 					scan->bm_bitmap &= ~mask;
448 				} else {
449 					scan->bm_bitmap &= ~mask;
450 					scan->bm_bitmap |= pmask;
451 				}
452 				return(r);
453 			}
454 		}
455 		blk += radix;
456 		mask <<= 2;
457 		pmask <<= 2;
458 	}
459 
460 	/*
461 	 * We couldn't allocate count in this subtree, update bighint.
462 	 */
463 	if (scan->bm_bighint >= count)
464 		scan->bm_bighint = count >> 1;
465 	return(ALIST_BLOCK_NONE);
466 }
467 
468 /*
469  * BLST_LEAF_FREE() -	free allocated block from leaf bitmap
470  *
471  */
472 static void
473 alst_leaf_free(
474 	almeta_t *scan,
475 	daddr_t blk,
476 	int count
477 ) {
478 	/*
479 	 * free some data in this bitmap
480 	 *
481 	 * e.g.
482 	 *	0000111111111110000
483 	 *          \_________/\__/
484 	 *		v        n
485 	 */
486 	int n = blk & (ALIST_BMAP_RADIX - 1);
487 	u_daddr_t mask;
488 
489 	mask = ((u_daddr_t)-1 << n) &
490 	    ((u_daddr_t)-1 >> (ALIST_BMAP_RADIX - count - n));
491 
492 	if (scan->bm_bitmap & mask)
493 		panic("alst_radix_free: freeing free block");
494 	scan->bm_bitmap |= mask;
495 
496 	/*
497 	 * We could probably do a better job here.  We are required to make
498 	 * bighint at least as large as the biggest contiguous block of
499 	 * data.  If we just shoehorn it, a little extra overhead will
500 	 * be incured on the next allocation (but only that one typically).
501 	 */
502 	scan->bm_bighint = ALIST_BMAP_RADIX;
503 }
504 
505 /*
506  * BLST_META_FREE() - free allocated blocks from radix tree meta info
507  *
508  *	This support routine frees a range of blocks from the bitmap.
509  *	The range must be entirely enclosed by this radix node.  If a
510  *	meta node, we break the range down recursively to free blocks
511  *	in subnodes (which means that this code can free an arbitrary
512  *	range whereas the allocation code cannot allocate an arbitrary
513  *	range).
514  */
515 
516 static void
517 alst_meta_free(
518 	almeta_t *scan,
519 	daddr_t freeBlk,
520 	daddr_t count,
521 	daddr_t radix,
522 	int skip,
523 	daddr_t blk
524 ) {
525 	int next_skip = ((u_int)skip / ALIST_META_RADIX);
526 	u_daddr_t mask;
527 	u_daddr_t pmask;
528 	int i;
529 
530 	/*
531 	 * Break the free down into its components.  Because it is so easy
532 	 * to implement, frees are not limited to power-of-2 sizes.
533 	 *
534 	 * Each block in a meta-node bitmap takes two bits.
535 	 */
536 	radix /= ALIST_META_RADIX;
537 
538 	i = (freeBlk - blk) / radix;
539 	blk += i * radix;
540 	mask = 0x00000003 << (i * 2);
541 	pmask = 0x00000001 << (i * 2);
542 
543 	i = i * next_skip + 1;
544 
545 	while (i <= skip && blk < freeBlk + count) {
546 		daddr_t v;
547 
548 		v = blk + radix - freeBlk;
549 		if (v > count)
550 			v = count;
551 
552 		if (scan->bm_bighint == (daddr_t)-1)
553 			panic("alst_meta_free: freeing unexpected range");
554 
555 		if (freeBlk == blk && count >= radix) {
556 			/*
557 			 * All-free case, no need to update sub-tree
558 			 */
559 			scan->bm_bitmap |= mask;
560 			scan->bm_bighint = radix * ALIST_META_RADIX;/*XXX*/
561 		} else {
562 			/*
563 			 * If we were previously marked all-allocated, fix-up
564 			 * the next layer so we can recurse down into it.
565 			 */
566 			if ((scan->bm_bitmap & mask) == 0) {
567 				scan[i].bm_bitmap = (u_daddr_t)0;
568 				scan[i].bm_bighint = 0;
569 			}
570 
571 			/*
572 			 * Recursion case
573 			 */
574 			if (next_skip == 1)
575 				alst_leaf_free(&scan[i], freeBlk, v);
576 			else
577 				alst_meta_free(&scan[i], freeBlk, v, radix, next_skip - 1, blk);
578 			if (scan[i].bm_bitmap == (u_daddr_t)-1)
579 				scan->bm_bitmap |= mask;
580 			else
581 				scan->bm_bitmap |= pmask;
582 			if (scan->bm_bighint < scan[i].bm_bighint)
583 			    scan->bm_bighint = scan[i].bm_bighint;
584 		}
585 		mask <<= 2;
586 		pmask <<= 2;
587 		count -= v;
588 		freeBlk += v;
589 		blk += radix;
590 		i += next_skip;
591 	}
592 }
593 
594 /*
595  * BLST_RADIX_INIT() - initialize radix tree
596  *
597  *	Initialize our meta structures and bitmaps and calculate the exact
598  *	amount of space required to manage 'count' blocks - this space may
599  *	be considerably less then the calculated radix due to the large
600  *	RADIX values we use.
601  */
602 
603 static daddr_t
604 alst_radix_init(almeta_t *scan, daddr_t radix, int skip, daddr_t count)
605 {
606 	int i;
607 	int next_skip;
608 	daddr_t memindex = 0;
609 	u_daddr_t mask;
610 	u_daddr_t pmask;
611 
612 	/*
613 	 * Leaf node
614 	 */
615 	if (radix == ALIST_BMAP_RADIX) {
616 		if (scan) {
617 			scan->bm_bighint = 0;
618 			scan->bm_bitmap = 0;
619 		}
620 		return(memindex);
621 	}
622 
623 	/*
624 	 * Meta node.  If allocating the entire object we can special
625 	 * case it.  However, we need to figure out how much memory
626 	 * is required to manage 'count' blocks, so we continue on anyway.
627 	 */
628 
629 	if (scan) {
630 		scan->bm_bighint = 0;
631 		scan->bm_bitmap = 0;
632 	}
633 
634 	radix /= ALIST_META_RADIX;
635 	next_skip = ((u_int)skip / ALIST_META_RADIX);
636 	mask = 0x00000003;
637 	pmask = 0x00000001;
638 
639 	for (i = 1; i <= skip; i += next_skip) {
640 		if (count >= radix) {
641 			/*
642 			 * Allocate the entire object
643 			 */
644 			memindex = i + alst_radix_init(
645 			    ((scan) ? &scan[i] : NULL),
646 			    radix,
647 			    next_skip - 1,
648 			    radix
649 			);
650 			count -= radix;
651 			/* already marked as wholely allocated */
652 		} else if (count > 0) {
653 			/*
654 			 * Allocate a partial object
655 			 */
656 			memindex = i + alst_radix_init(
657 			    ((scan) ? &scan[i] : NULL),
658 			    radix,
659 			    next_skip - 1,
660 			    count
661 			);
662 			count = 0;
663 
664 			/*
665 			 * Mark as partially allocated
666 			 */
667 			if (scan)
668 				scan->bm_bitmap |= pmask;
669 		} else {
670 			/*
671 			 * Add terminator and break out
672 			 */
673 			if (scan)
674 				scan[i].bm_bighint = (daddr_t)-1;
675 			/* already marked as wholely allocated */
676 			break;
677 		}
678 		mask <<= 2;
679 		pmask <<= 2;
680 	}
681 	if (memindex < i)
682 		memindex = i;
683 	return(memindex);
684 }
685 
686 #ifdef ALIST_DEBUG
687 
688 static void
689 alst_radix_print(almeta_t *scan, daddr_t blk, daddr_t radix, int skip, int tab)
690 {
691 	int i;
692 	int next_skip;
693 	int lastState = 0;
694 	u_daddr_t mask;
695 
696 	if (radix == ALIST_BMAP_RADIX) {
697 		kprintf(
698 		    "%*.*s(%04x,%d): bitmap %08x big=%d\n",
699 		    tab, tab, "",
700 		    blk, radix,
701 		    scan->bm_bitmap,
702 		    scan->bm_bighint
703 		);
704 		return;
705 	}
706 
707 	if (scan->bm_bitmap == 0) {
708 		kprintf(
709 		    "%*.*s(%04x,%d) ALL ALLOCATED\n",
710 		    tab, tab, "",
711 		    blk,
712 		    radix
713 		);
714 		return;
715 	}
716 	if (scan->bm_bitmap == (u_daddr_t)-1) {
717 		kprintf(
718 		    "%*.*s(%04x,%d) ALL FREE\n",
719 		    tab, tab, "",
720 		    blk,
721 		    radix
722 		);
723 		return;
724 	}
725 
726 	kprintf(
727 	    "%*.*s(%04x,%d): subtree (%d) bitmap=%08x big=%d {\n",
728 	    tab, tab, "",
729 	    blk, radix,
730 	    radix,
731 	    scan->bm_bitmap,
732 	    scan->bm_bighint
733 	);
734 
735 	radix /= ALIST_META_RADIX;
736 	next_skip = ((u_int)skip / ALIST_META_RADIX);
737 	tab += 4;
738 	mask = 0x00000003;
739 
740 	for (i = 1; i <= skip; i += next_skip) {
741 		if (scan[i].bm_bighint == (daddr_t)-1) {
742 			kprintf(
743 			    "%*.*s(%04x,%d): Terminator\n",
744 			    tab, tab, "",
745 			    blk, radix
746 			);
747 			lastState = 0;
748 			break;
749 		}
750 		if ((scan->bm_bitmap & mask) == mask) {
751 			kprintf(
752 			    "%*.*s(%04x,%d): ALL FREE\n",
753 			    tab, tab, "",
754 			    blk, radix
755 			);
756 		} else if ((scan->bm_bitmap & mask) == 0) {
757 			kprintf(
758 			    "%*.*s(%04x,%d): ALL ALLOCATED\n",
759 			    tab, tab, "",
760 			    blk, radix
761 			);
762 		} else {
763 			alst_radix_print(
764 			    &scan[i],
765 			    blk,
766 			    radix,
767 			    next_skip - 1,
768 			    tab
769 			);
770 		}
771 		blk += radix;
772 		mask <<= 2;
773 	}
774 	tab -= 4;
775 
776 	kprintf(
777 	    "%*.*s}\n",
778 	    tab, tab, ""
779 	);
780 }
781 
782 #endif
783 
784 #ifdef ALIST_DEBUG
785 
786 int
787 main(int ac, char **av)
788 {
789 	int size = 1024;
790 	int i;
791 	alist_t bl;
792 
793 	for (i = 1; i < ac; ++i) {
794 		const char *ptr = av[i];
795 		if (*ptr != '-') {
796 			size = strtol(ptr, NULL, 0);
797 			continue;
798 		}
799 		ptr += 2;
800 		fprintf(stderr, "Bad option: %s\n", ptr - 2);
801 		exit(1);
802 	}
803 	bl = alist_create(size, NULL);
804 	alist_free(bl, 0, size);
805 
806 	for (;;) {
807 		char buf[1024];
808 		daddr_t da = 0;
809 		daddr_t count = 0;
810 
811 
812 		kprintf("%d/%d/%d> ", bl->bl_free, size, bl->bl_radix);
813 		fflush(stdout);
814 		if (fgets(buf, sizeof(buf), stdin) == NULL)
815 			break;
816 		switch(buf[0]) {
817 		case 'p':
818 			alist_print(bl);
819 			break;
820 		case 'a':
821 			if (sscanf(buf + 1, "%d", &count) == 1) {
822 				daddr_t blk = alist_alloc(bl, count);
823 				kprintf("    R=%04x\n", blk);
824 			} else {
825 				kprintf("?\n");
826 			}
827 			break;
828 		case 'f':
829 			if (sscanf(buf + 1, "%x %d", &da, &count) == 2) {
830 				alist_free(bl, da, count);
831 			} else {
832 				kprintf("?\n");
833 			}
834 			break;
835 		case '?':
836 		case 'h':
837 			puts(
838 			    "p          -print\n"
839 			    "a %d       -allocate\n"
840 			    "f %x %d    -free\n"
841 			    "h/?        -help"
842 			);
843 			break;
844 		default:
845 			kprintf("?\n");
846 			break;
847 		}
848 	}
849 	return(0);
850 }
851 
852 void
853 panic(const char *ctl, ...)
854 {
855 	__va_list va;
856 
857 	__va_start(va, ctl);
858 	vfprintf(stderr, ctl, va);
859 	fprintf(stderr, "\n");
860 	__va_end(va);
861 	exit(1);
862 }
863 
864 #endif
865 
866