aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/zstd/lib/compress/zstd_cwksp.h
blob: 97676693b5eed10b306e1eaa05f3bd3744e95aa6 (plain) (blame)
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
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 * All rights reserved.
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 * You may select, at your option, one of the above-listed licenses.
 */

#ifndef ZSTD_CWKSP_H
#define ZSTD_CWKSP_H

/*-*************************************
*  Dependencies
***************************************/
#include "../common/zstd_internal.h"

#if defined (__cplusplus)
extern "C" {
#endif

/*-*************************************
*  Constants
***************************************/

/* Since the workspace is effectively its own little malloc implementation /
 * arena, when we run under ASAN, we should similarly insert redzones between
 * each internal element of the workspace, so ASAN will catch overruns that
 * reach outside an object but that stay inside the workspace.
 *
 * This defines the size of that redzone.
 */
#ifndef ZSTD_CWKSP_ASAN_REDZONE_SIZE
#define ZSTD_CWKSP_ASAN_REDZONE_SIZE 128
#endif


/* Set our tables and aligneds to align by 64 bytes */
#define ZSTD_CWKSP_ALIGNMENT_BYTES 64

/*-*************************************
*  Structures
***************************************/
typedef enum {
    ZSTD_cwksp_alloc_objects,
    ZSTD_cwksp_alloc_buffers,
    ZSTD_cwksp_alloc_aligned
} ZSTD_cwksp_alloc_phase_e;

/**
 * Used to describe whether the workspace is statically allocated (and will not
 * necessarily ever be freed), or if it's dynamically allocated and we can
 * expect a well-formed caller to free this.
 */
typedef enum {
    ZSTD_cwksp_dynamic_alloc,
    ZSTD_cwksp_static_alloc
} ZSTD_cwksp_static_alloc_e;

/**
 * Zstd fits all its internal datastructures into a single continuous buffer,
 * so that it only needs to perform a single OS allocation (or so that a buffer
 * can be provided to it and it can perform no allocations at all). This buffer
 * is called the workspace.
 *
 * Several optimizations complicate that process of allocating memory ranges
 * from this workspace for each internal datastructure:
 *
 * - These different internal datastructures have different setup requirements:
 *
 *   - The static objects need to be cleared once and can then be trivially
 *     reused for each compression.
 *
 *   - Various buffers don't need to be initialized at all--they are always
 *     written into before they're read.
 *
 *   - The matchstate tables have a unique requirement that they don't need
 *     their memory to be totally cleared, but they do need the memory to have
 *     some bound, i.e., a guarantee that all values in the memory they've been
 *     allocated is less than some maximum value (which is the starting value
 *     for the indices that they will then use for compression). When this
 *     guarantee is provided to them, they can use the memory without any setup
 *     work. When it can't, they have to clear the area.
 *
 * - These buffers also have different alignment requirements.
 *
 * - We would like to reuse the objects in the workspace for multiple
 *   compressions without having to perform any expensive reallocation or
 *   reinitialization work.
 *
 * - We would like to be able to efficiently reuse the workspace across
 *   multiple compressions **even when the compression parameters change** and
 *   we need to resize some of the objects (where possible).
 *
 * To attempt to manage this buffer, given these constraints, the ZSTD_cwksp
 * abstraction was created. It works as follows:
 *
 * Workspace Layout:
 *
 * [                        ... workspace ...                         ]
 * [objects][tables ... ->] free space [<- ... aligned][<- ... buffers]
 *
 * The various objects that live in the workspace are divided into the
 * following categories, and are allocated separately:
 *
 * - Static objects: this is optionally the enclosing ZSTD_CCtx or ZSTD_CDict,
 *   so that literally everything fits in a single buffer. Note: if present,
 *   this must be the first object in the workspace, since ZSTD_customFree{CCtx,
 *   CDict}() rely on a pointer comparison to see whether one or two frees are
 *   required.
 *
 * - Fixed size objects: these are fixed-size, fixed-count objects that are
 *   nonetheless "dynamically" allocated in the workspace so that we can
 *   control how they're initialized separately from the broader ZSTD_CCtx.
 *   Examples:
 *   - Entropy Workspace
 *   - 2 x ZSTD_compressedBlockState_t
 *   - CDict dictionary contents
 *
 * - Tables: these are any of several different datastructures (hash tables,
 *   chain tables, binary trees) that all respect a common format: they are
 *   uint32_t arrays, all of whose values are between 0 and (nextSrc - base).
 *   Their sizes depend on the cparams. These tables are 64-byte aligned.
 *
 * - Aligned: these buffers are used for various purposes that require 4 byte
 *   alignment, but don't require any initialization before they're used. These
 *   buffers are each aligned to 64 bytes.
 *
 * - Buffers: these buffers are used for various purposes that don't require
 *   any alignment or initialization before they're used. This means they can
 *   be moved around at no cost for a new compression.
 *
 * Allocating Memory:
 *
 * The various types of objects must be allocated in order, so they can be
 * correctly packed into the workspace buffer. That order is:
 *
 * 1. Objects
 * 2. Buffers
 * 3. Aligned/Tables
 *
 * Attempts to reserve objects of different types out of order will fail.
 */
typedef struct {
    void* workspace;
    void* workspaceEnd;

    void* objectEnd;
    void* tableEnd;
    void* tableValidEnd;
    void* allocStart;

    BYTE allocFailed;
    int workspaceOversizedDuration;
    ZSTD_cwksp_alloc_phase_e phase;
    ZSTD_cwksp_static_alloc_e isStatic;
} ZSTD_cwksp;

/*-*************************************
*  Functions
***************************************/

MEM_STATIC size_t ZSTD_cwksp_available_space(ZSTD_cwksp* ws);

MEM_STATIC void ZSTD_cwksp_assert_internal_consistency(ZSTD_cwksp* ws) {
    (void)ws;
    assert(ws->workspace <= ws->objectEnd);
    assert(ws->objectEnd <= ws->tableEnd);
    assert(ws->objectEnd <= ws->tableValidEnd);
    assert(ws->tableEnd <= ws->allocStart);
    assert(ws->tableValidEnd <= ws->allocStart);
    assert(ws->allocStart <= ws->workspaceEnd);
}

/**
 * Align must be a power of 2.
 */
MEM_STATIC size_t ZSTD_cwksp_align(size_t size, size_t const align) {
    size_t const mask = align - 1;
    assert((align & mask) == 0);
    return (size + mask) & ~mask;
}

/**
 * Use this to determine how much space in the workspace we will consume to
 * allocate this object. (Normally it should be exactly the size of the object,
 * but under special conditions, like ASAN, where we pad each object, it might
 * be larger.)
 *
 * Since tables aren't currently redzoned, you don't need to call through this
 * to figure out how much space you need for the matchState tables. Everything
 * else is though.
 *
 * Do not use for sizing aligned buffers. Instead, use ZSTD_cwksp_aligned_alloc_size().
 */
MEM_STATIC size_t ZSTD_cwksp_alloc_size(size_t size) {
    if (size == 0)
        return 0;
#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    return size + 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE;
#else
    return size;
#endif
}

/**
 * Returns an adjusted alloc size that is the nearest larger multiple of 64 bytes.
 * Used to determine the number of bytes required for a given "aligned".
 */
MEM_STATIC size_t ZSTD_cwksp_aligned_alloc_size(size_t size) {
    return ZSTD_cwksp_alloc_size(ZSTD_cwksp_align(size, ZSTD_CWKSP_ALIGNMENT_BYTES));
}

/**
 * Returns the amount of additional space the cwksp must allocate
 * for internal purposes (currently only alignment).
 */
MEM_STATIC size_t ZSTD_cwksp_slack_space_required(void) {
    /* For alignment, the wksp will always allocate an additional n_1=[1, 64] bytes
     * to align the beginning of tables section, as well as another n_2=[0, 63] bytes
     * to align the beginning of the aligned section.
     *
     * n_1 + n_2 == 64 bytes if the cwksp is freshly allocated, due to tables and
     * aligneds being sized in multiples of 64 bytes.
     */
    size_t const slackSpace = ZSTD_CWKSP_ALIGNMENT_BYTES;
    return slackSpace;
}


/**
 * Return the number of additional bytes required to align a pointer to the given number of bytes.
 * alignBytes must be a power of two.
 */
MEM_STATIC size_t ZSTD_cwksp_bytes_to_align_ptr(void* ptr, const size_t alignBytes) {
    size_t const alignBytesMask = alignBytes - 1;
    size_t const bytes = (alignBytes - ((size_t)ptr & (alignBytesMask))) & alignBytesMask;
    assert((alignBytes & alignBytesMask) == 0);
    assert(bytes != ZSTD_CWKSP_ALIGNMENT_BYTES);
    return bytes;
}

/**
 * Internal function. Do not use directly.
 * Reserves the given number of bytes within the aligned/buffer segment of the wksp,
 * which counts from the end of the wksp (as opposed to the object/table segment).
 *
 * Returns a pointer to the beginning of that space.
 */
MEM_STATIC void*
ZSTD_cwksp_reserve_internal_buffer_space(ZSTD_cwksp* ws, size_t const bytes)
{
    void* const alloc = (BYTE*)ws->allocStart - bytes;
    void* const bottom = ws->tableEnd;
    DEBUGLOG(5, "cwksp: reserving %p %zd bytes, %zd bytes remaining",
        alloc, bytes, ZSTD_cwksp_available_space(ws) - bytes);
    ZSTD_cwksp_assert_internal_consistency(ws);
    assert(alloc >= bottom);
    if (alloc < bottom) {
        DEBUGLOG(4, "cwksp: alloc failed!");
        ws->allocFailed = 1;
        return NULL;
    }
    /* the area is reserved from the end of wksp.
     * If it overlaps with tableValidEnd, it voids guarantees on values' range */
    if (alloc < ws->tableValidEnd) {
        ws->tableValidEnd = alloc;
    }
    ws->allocStart = alloc;
    return alloc;
}

/**
 * Moves the cwksp to the next phase, and does any necessary allocations.
 * cwksp initialization must necessarily go through each phase in order.
 * Returns a 0 on success, or zstd error
 */
MEM_STATIC size_t
ZSTD_cwksp_internal_advance_phase(ZSTD_cwksp* ws, ZSTD_cwksp_alloc_phase_e phase)
{
    assert(phase >= ws->phase);
    if (phase > ws->phase) {
        /* Going from allocating objects to allocating buffers */
        if (ws->phase < ZSTD_cwksp_alloc_buffers &&
                phase >= ZSTD_cwksp_alloc_buffers) {
            ws->tableValidEnd = ws->objectEnd;
        }

        /* Going from allocating buffers to allocating aligneds/tables */
        if (ws->phase < ZSTD_cwksp_alloc_aligned &&
                phase >= ZSTD_cwksp_alloc_aligned) {
            {   /* Align the start of the "aligned" to 64 bytes. Use [1, 64] bytes. */
                size_t const bytesToAlign =
                    ZSTD_CWKSP_ALIGNMENT_BYTES - ZSTD_cwksp_bytes_to_align_ptr(ws->allocStart, ZSTD_CWKSP_ALIGNMENT_BYTES);
                DEBUGLOG(5, "reserving aligned alignment addtl space: %zu", bytesToAlign);
                ZSTD_STATIC_ASSERT((ZSTD_CWKSP_ALIGNMENT_BYTES & (ZSTD_CWKSP_ALIGNMENT_BYTES - 1)) == 0); /* power of 2 */
                RETURN_ERROR_IF(!ZSTD_cwksp_reserve_internal_buffer_space(ws, bytesToAlign),
                                memory_allocation, "aligned phase - alignment initial allocation failed!");
            }
            {   /* Align the start of the tables to 64 bytes. Use [0, 63] bytes */
                void* const alloc = ws->objectEnd;
                size_t const bytesToAlign = ZSTD_cwksp_bytes_to_align_ptr(alloc, ZSTD_CWKSP_ALIGNMENT_BYTES);
                void* const objectEnd = (BYTE*)alloc + bytesToAlign;
                DEBUGLOG(5, "reserving table alignment addtl space: %zu", bytesToAlign);
                RETURN_ERROR_IF(objectEnd > ws->workspaceEnd, memory_allocation,
                                "table phase - alignment initial allocation failed!");
                ws->objectEnd = objectEnd;
                ws->tableEnd = objectEnd;  /* table area starts being empty */
                if (ws->tableValidEnd < ws->tableEnd) {
                    ws->tableValidEnd = ws->tableEnd;
        }   }   }
        ws->phase = phase;
        ZSTD_cwksp_assert_internal_consistency(ws);
    }
    return 0;
}

/**
 * Returns whether this object/buffer/etc was allocated in this workspace.
 */
MEM_STATIC int ZSTD_cwksp_owns_buffer(const ZSTD_cwksp* ws, const void* ptr)
{
    return (ptr != NULL) && (ws->workspace <= ptr) && (ptr <= ws->workspaceEnd);
}

/**
 * Internal function. Do not use directly.
 */
MEM_STATIC void*
ZSTD_cwksp_reserve_internal(ZSTD_cwksp* ws, size_t bytes, ZSTD_cwksp_alloc_phase_e phase)
{
    void* alloc;
    if (ZSTD_isError(ZSTD_cwksp_internal_advance_phase(ws, phase)) || bytes == 0) {
        return NULL;
    }

#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* over-reserve space */
    bytes += 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE;
#endif

    alloc = ZSTD_cwksp_reserve_internal_buffer_space(ws, bytes);

#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* Move alloc so there's ZSTD_CWKSP_ASAN_REDZONE_SIZE unused space on
     * either size. */
    if (alloc) {
        alloc = (BYTE *)alloc + ZSTD_CWKSP_ASAN_REDZONE_SIZE;
        if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
            /* We need to keep the redzone poisoned while unpoisoning the bytes that
             * are actually allocated. */
            __asan_unpoison_memory_region(alloc, bytes - 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE);
        }
    }
#endif

    return alloc;
}

/**
 * Reserves and returns unaligned memory.
 */
MEM_STATIC BYTE* ZSTD_cwksp_reserve_buffer(ZSTD_cwksp* ws, size_t bytes)
{
    return (BYTE*)ZSTD_cwksp_reserve_internal(ws, bytes, ZSTD_cwksp_alloc_buffers);
}

/**
 * Reserves and returns memory sized on and aligned on ZSTD_CWKSP_ALIGNMENT_BYTES (64 bytes).
 */
MEM_STATIC void* ZSTD_cwksp_reserve_aligned(ZSTD_cwksp* ws, size_t bytes)
{
    void* ptr = ZSTD_cwksp_reserve_internal(ws, ZSTD_cwksp_align(bytes, ZSTD_CWKSP_ALIGNMENT_BYTES),
                                            ZSTD_cwksp_alloc_aligned);
    assert(((size_t)ptr & (ZSTD_CWKSP_ALIGNMENT_BYTES-1))== 0);
    return ptr;
}

/**
 * Aligned on 64 bytes. These buffers have the special property that
 * their values remain constrained, allowing us to re-use them without
 * memset()-ing them.
 */
MEM_STATIC void* ZSTD_cwksp_reserve_table(ZSTD_cwksp* ws, size_t bytes)
{
    const ZSTD_cwksp_alloc_phase_e phase = ZSTD_cwksp_alloc_aligned;
    void* alloc;
    void* end;
    void* top;

    if (ZSTD_isError(ZSTD_cwksp_internal_advance_phase(ws, phase))) {
        return NULL;
    }
    alloc = ws->tableEnd;
    end = (BYTE *)alloc + bytes;
    top = ws->allocStart;

    DEBUGLOG(5, "cwksp: reserving %p table %zd bytes, %zd bytes remaining",
        alloc, bytes, ZSTD_cwksp_available_space(ws) - bytes);
    assert((bytes & (sizeof(U32)-1)) == 0);
    ZSTD_cwksp_assert_internal_consistency(ws);
    assert(end <= top);
    if (end > top) {
        DEBUGLOG(4, "cwksp: table alloc failed!");
        ws->allocFailed = 1;
        return NULL;
    }
    ws->tableEnd = end;

#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
        __asan_unpoison_memory_region(alloc, bytes);
    }
#endif

    assert((bytes & (ZSTD_CWKSP_ALIGNMENT_BYTES-1)) == 0);
    assert(((size_t)alloc & (ZSTD_CWKSP_ALIGNMENT_BYTES-1))== 0);
    return alloc;
}

/**
 * Aligned on sizeof(void*).
 * Note : should happen only once, at workspace first initialization
 */
MEM_STATIC void* ZSTD_cwksp_reserve_object(ZSTD_cwksp* ws, size_t bytes)
{
    size_t const roundedBytes = ZSTD_cwksp_align(bytes, sizeof(void*));
    void* alloc = ws->objectEnd;
    void* end = (BYTE*)alloc + roundedBytes;

#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* over-reserve space */
    end = (BYTE *)end + 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE;
#endif

    DEBUGLOG(4,
        "cwksp: reserving %p object %zd bytes (rounded to %zd), %zd bytes remaining",
        alloc, bytes, roundedBytes, ZSTD_cwksp_available_space(ws) - roundedBytes);
    assert((size_t)alloc % ZSTD_ALIGNOF(void*) == 0);
    assert(bytes % ZSTD_ALIGNOF(void*) == 0);
    ZSTD_cwksp_assert_internal_consistency(ws);
    /* we must be in the first phase, no advance is possible */
    if (ws->phase != ZSTD_cwksp_alloc_objects || end > ws->workspaceEnd) {
        DEBUGLOG(3, "cwksp: object alloc failed!");
        ws->allocFailed = 1;
        return NULL;
    }
    ws->objectEnd = end;
    ws->tableEnd = end;
    ws->tableValidEnd = end;

#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* Move alloc so there's ZSTD_CWKSP_ASAN_REDZONE_SIZE unused space on
     * either size. */
    alloc = (BYTE*)alloc + ZSTD_CWKSP_ASAN_REDZONE_SIZE;
    if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
        __asan_unpoison_memory_region(alloc, bytes);
    }
#endif

    return alloc;
}

MEM_STATIC void ZSTD_cwksp_mark_tables_dirty(ZSTD_cwksp* ws)
{
    DEBUGLOG(4, "cwksp: ZSTD_cwksp_mark_tables_dirty");

#if ZSTD_MEMORY_SANITIZER && !defined (ZSTD_MSAN_DONT_POISON_WORKSPACE)
    /* To validate that the table re-use logic is sound, and that we don't
     * access table space that we haven't cleaned, we re-"poison" the table
     * space every time we mark it dirty. */
    {
        size_t size = (BYTE*)ws->tableValidEnd - (BYTE*)ws->objectEnd;
        assert(__msan_test_shadow(ws->objectEnd, size) == -1);
        __msan_poison(ws->objectEnd, size);
    }
#endif

    assert(ws->tableValidEnd >= ws->objectEnd);
    assert(ws->tableValidEnd <= ws->allocStart);
    ws->tableValidEnd = ws->objectEnd;
    ZSTD_cwksp_assert_internal_consistency(ws);
}

MEM_STATIC void ZSTD_cwksp_mark_tables_clean(ZSTD_cwksp* ws) {
    DEBUGLOG(4, "cwksp: ZSTD_cwksp_mark_tables_clean");
    assert(ws->tableValidEnd >= ws->objectEnd);
    assert(ws->tableValidEnd <= ws->allocStart);
    if (ws->tableValidEnd < ws->tableEnd) {
        ws->tableValidEnd = ws->tableEnd;
    }
    ZSTD_cwksp_assert_internal_consistency(ws);
}

/**
 * Zero the part of the allocated tables not already marked clean.
 */
MEM_STATIC void ZSTD_cwksp_clean_tables(ZSTD_cwksp* ws) {
    DEBUGLOG(4, "cwksp: ZSTD_cwksp_clean_tables");
    assert(ws->tableValidEnd >= ws->objectEnd);
    assert(ws->tableValidEnd <= ws->allocStart);
    if (ws->tableValidEnd < ws->tableEnd) {
        ZSTD_memset(ws->tableValidEnd, 0, (size_t)((BYTE*)ws->tableEnd - (BYTE*)ws->tableValidEnd));
    }
    ZSTD_cwksp_mark_tables_clean(ws);
}

/**
 * Invalidates table allocations.
 * All other allocations remain valid.
 */
MEM_STATIC void ZSTD_cwksp_clear_tables(ZSTD_cwksp* ws) {
    DEBUGLOG(4, "cwksp: clearing tables!");

#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* We don't do this when the workspace is statically allocated, because
     * when that is the case, we have no capability to hook into the end of the
     * workspace's lifecycle to unpoison the memory.
     */
    if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
        size_t size = (BYTE*)ws->tableValidEnd - (BYTE*)ws->objectEnd;
        __asan_poison_memory_region(ws->objectEnd, size);
    }
#endif

    ws->tableEnd = ws->objectEnd;
    ZSTD_cwksp_assert_internal_consistency(ws);
}

/**
 * Invalidates all buffer, aligned, and table allocations.
 * Object allocations remain valid.
 */
MEM_STATIC void ZSTD_cwksp_clear(ZSTD_cwksp* ws) {
    DEBUGLOG(4, "cwksp: clearing!");

#if ZSTD_MEMORY_SANITIZER && !defined (ZSTD_MSAN_DONT_POISON_WORKSPACE)
    /* To validate that the context re-use logic is sound, and that we don't
     * access stuff that this compression hasn't initialized, we re-"poison"
     * the workspace (or at least the non-static, non-table parts of it)
     * every time we start a new compression. */
    {
        size_t size = (BYTE*)ws->workspaceEnd - (BYTE*)ws->tableValidEnd;
        __msan_poison(ws->tableValidEnd, size);
    }
#endif

#if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
    /* We don't do this when the workspace is statically allocated, because
     * when that is the case, we have no capability to hook into the end of the
     * workspace's lifecycle to unpoison the memory.
     */
    if (ws->isStatic == ZSTD_cwksp_dynamic_alloc) {
        size_t size = (BYTE*)ws->workspaceEnd - (BYTE*)ws->objectEnd;
        __asan_poison_memory_region(ws->objectEnd, size);
    }
#endif

    ws->tableEnd = ws->objectEnd;
    ws->allocStart = ws->workspaceEnd;
    ws->allocFailed = 0;
    if (ws->phase > ZSTD_cwksp_alloc_buffers) {
        ws->phase = ZSTD_cwksp_alloc_buffers;
    }
    ZSTD_cwksp_assert_internal_consistency(ws);
}

/**
 * The provided workspace takes ownership of the buffer [start, start+size).
 * Any existing values in the workspace are ignored (the previously managed
 * buffer, if present, must be separately freed).
 */
MEM_STATIC void ZSTD_cwksp_init(ZSTD_cwksp* ws, void* start, size_t size, ZSTD_cwksp_static_alloc_e isStatic) {
    DEBUGLOG(4, "cwksp: init'ing workspace with %zd bytes", size);
    assert(((size_t)start & (sizeof(void*)-1)) == 0); /* ensure correct alignment */
    ws->workspace = start;
    ws->workspaceEnd = (BYTE*)start + size;
    ws->objectEnd = ws->workspace;
    ws->tableValidEnd = ws->objectEnd;
    ws->phase = ZSTD_cwksp_alloc_objects;
    ws->isStatic = isStatic;
    ZSTD_cwksp_clear(ws);
    ws->workspaceOversizedDuration = 0;
    ZSTD_cwksp_assert_internal_consistency(ws);
}

MEM_STATIC size_t ZSTD_cwksp_create(ZSTD_cwksp* ws, size_t size, ZSTD_customMem customMem) {
    void* workspace = ZSTD_customMalloc(size, customMem);
    DEBUGLOG(4, "cwksp: creating new workspace with %zd bytes", size);
    RETURN_ERROR_IF(workspace == NULL, memory_allocation, "NULL pointer!");
    ZSTD_cwksp_init(ws, workspace, size, ZSTD_cwksp_dynamic_alloc);
    return 0;
}

MEM_STATIC void ZSTD_cwksp_free(ZSTD_cwksp* ws, ZSTD_customMem customMem) {
    void *ptr = ws->workspace;
    DEBUGLOG(4, "cwksp: freeing workspace");
    ZSTD_memset(ws, 0, sizeof(ZSTD_cwksp));
    ZSTD_customFree(ptr, customMem);
}

/**
 * Moves the management of a workspace from one cwksp to another. The src cwksp
 * is left in an invalid state (src must be re-init()'ed before it's used again).
 */
MEM_STATIC void ZSTD_cwksp_move(ZSTD_cwksp* dst, ZSTD_cwksp* src) {
    *dst = *src;
    ZSTD_memset(src, 0, sizeof(ZSTD_cwksp));
}

MEM_STATIC size_t ZSTD_cwksp_sizeof(const ZSTD_cwksp* ws) {
    return (size_t)((BYTE*)ws->workspaceEnd - (BYTE*)ws->workspace);
}

MEM_STATIC size_t ZSTD_cwksp_used(const ZSTD_cwksp* ws) {
    return (size_t)((BYTE*)ws->tableEnd - (BYTE*)ws->workspace)
         + (size_t)((BYTE*)ws->workspaceEnd - (BYTE*)ws->allocStart);
}

MEM_STATIC int ZSTD_cwksp_reserve_failed(const ZSTD_cwksp* ws) {
    return ws->allocFailed;
}

/*-*************************************
*  Functions Checking Free Space
***************************************/

/* ZSTD_alignmentSpaceWithinBounds() :
 * Returns if the estimated space needed for a wksp is within an acceptable limit of the
 * actual amount of space used.
 */
MEM_STATIC int ZSTD_cwksp_estimated_space_within_bounds(const ZSTD_cwksp* const ws,
                                                        size_t const estimatedSpace, int resizedWorkspace) {
    if (resizedWorkspace) {
        /* Resized/newly allocated wksp should have exact bounds */
        return ZSTD_cwksp_used(ws) == estimatedSpace;
    } else {
        /* Due to alignment, when reusing a workspace, we can actually consume 63 fewer or more bytes
         * than estimatedSpace. See the comments in zstd_cwksp.h for details.
         */
        return (ZSTD_cwksp_used(ws) >= estimatedSpace - 63) && (ZSTD_cwksp_used(ws) <= estimatedSpace + 63);
    }
}


MEM_STATIC size_t ZSTD_cwksp_available_space(ZSTD_cwksp* ws) {
    return (size_t)((BYTE*)ws->allocStart - (BYTE*)ws->tableEnd);
}

MEM_STATIC int ZSTD_cwksp_check_available(ZSTD_cwksp* ws, size_t additionalNeededSpace) {
    return ZSTD_cwksp_available_space(ws) >= additionalNeededSpace;
}

MEM_STATIC int ZSTD_cwksp_check_too_large(ZSTD_cwksp* ws, size_t additionalNeededSpace) {
    return ZSTD_cwksp_check_available(
        ws, additionalNeededSpace * ZSTD_WORKSPACETOOLARGE_FACTOR);
}

MEM_STATIC int ZSTD_cwksp_check_wasteful(ZSTD_cwksp* ws, size_t additionalNeededSpace) {
    return ZSTD_cwksp_check_too_large(ws, additionalNeededSpace)
        && ws->workspaceOversizedDuration > ZSTD_WORKSPACETOOLARGE_MAXDURATION;
}

MEM_STATIC void ZSTD_cwksp_bump_oversized_duration(
        ZSTD_cwksp* ws, size_t additionalNeededSpace) {
    if (ZSTD_cwksp_check_too_large(ws, additionalNeededSpace)) {
        ws->workspaceOversizedDuration++;
    } else {
        ws->workspaceOversizedDuration = 0;
    }
}

#if defined (__cplusplus)
}
#endif

#endif /* ZSTD_CWKSP_H */