1 /*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #ifndef SkTypes_DEFINED
9 #define SkTypes_DEFINED
10
11 // IWYU pragma: begin_exports
12 #include "SkPreConfig.h"
13 #include "SkUserConfig.h"
14 #include "SkPostConfig.h"
15 #include <stddef.h>
16 #include <stdint.h>
17
18 #if defined(SK_ARM_HAS_NEON)
19 #include <arm_neon.h>
20 #elif SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
21 #include <immintrin.h>
22 #endif
23 // IWYU pragma: end_exports
24
25 #include <string.h>
26
27 /**
28 * sk_careful_memcpy() is just like memcpy(), but guards against undefined behavior.
29 *
30 * It is undefined behavior to call memcpy() with null dst or src, even if len is 0.
31 * If an optimizer is "smart" enough, it can exploit this to do unexpected things.
32 * memcpy(dst, src, 0);
33 * if (src) {
34 * printf("%x\n", *src);
35 * }
36 * In this code the compiler can assume src is not null and omit the if (src) {...} check,
37 * unconditionally running the printf, crashing the program if src really is null.
38 * Of the compilers we pay attention to only GCC performs this optimization in practice.
39 */
sk_careful_memcpy(void * dst,const void * src,size_t len)40 static inline void* sk_careful_memcpy(void* dst, const void* src, size_t len) {
41 // When we pass >0 len we had better already be passing valid pointers.
42 // So we just need to skip calling memcpy when len == 0.
43 if (len) {
44 memcpy(dst,src,len);
45 }
46 return dst;
47 }
48
49 /** \file SkTypes.h
50 */
51
52 /** See SkGraphics::GetVersion() to retrieve these at runtime
53 */
54 #define SKIA_VERSION_MAJOR 1
55 #define SKIA_VERSION_MINOR 0
56 #define SKIA_VERSION_PATCH 0
57
58 /*
59 memory wrappers to be implemented by the porting layer (platform)
60 */
61
62 /** Called internally if we run out of memory. The platform implementation must
63 not return, but should either throw an exception or otherwise exit.
64 */
65 SK_API extern void sk_out_of_memory(void);
66 /** Called internally if we hit an unrecoverable error.
67 The platform implementation must not return, but should either throw
68 an exception or otherwise exit.
69 */
70 SK_API extern void sk_abort_no_print(void);
71
72 enum {
73 SK_MALLOC_TEMP = 0x01, //!< hint to sk_malloc that the requested memory will be freed in the scope of the stack frame
74 SK_MALLOC_THROW = 0x02 //!< instructs sk_malloc to call sk_throw if the memory cannot be allocated.
75 };
76 /** Return a block of memory (at least 4-byte aligned) of at least the
77 specified size. If the requested memory cannot be returned, either
78 return null (if SK_MALLOC_TEMP bit is clear) or throw an exception
79 (if SK_MALLOC_TEMP bit is set). To free the memory, call sk_free().
80 */
81 SK_API extern void* sk_malloc_flags(size_t size, unsigned flags);
82 /** Same as sk_malloc(), but hard coded to pass SK_MALLOC_THROW as the flag
83 */
84 SK_API extern void* sk_malloc_throw(size_t size);
85 /** Same as standard realloc(), but this one never returns null on failure. It will throw
86 an exception if it fails.
87 */
88 SK_API extern void* sk_realloc_throw(void* buffer, size_t size);
89 /** Free memory returned by sk_malloc(). It is safe to pass null.
90 */
91 SK_API extern void sk_free(void*);
92
93 /** Much like calloc: returns a pointer to at least size zero bytes, or NULL on failure.
94 */
95 SK_API extern void* sk_calloc(size_t size);
96
97 /** Same as sk_calloc, but throws an exception instead of returning NULL on failure.
98 */
99 SK_API extern void* sk_calloc_throw(size_t size);
100
101 // bzero is safer than memset, but we can't rely on it, so... sk_bzero()
sk_bzero(void * buffer,size_t size)102 static inline void sk_bzero(void* buffer, size_t size) {
103 // Please c.f. sk_careful_memcpy. It's undefined behavior to call memset(null, 0, 0).
104 if (size) {
105 memset(buffer, 0, size);
106 }
107 }
108
109 ///////////////////////////////////////////////////////////////////////////////
110
111 #ifdef override_GLOBAL_NEW
112 #include <new>
113
new(size_t size)114 inline void* operator new(size_t size) {
115 return sk_malloc_throw(size);
116 }
117
delete(void * p)118 inline void operator delete(void* p) {
119 sk_free(p);
120 }
121 #endif
122
123 ///////////////////////////////////////////////////////////////////////////////
124
125 #define SK_INIT_TO_AVOID_WARNING = 0
126
127 #ifndef SkDebugf
128 SK_API void SkDebugf(const char format[], ...);
129 #endif
130
131 #define SkASSERT_RELEASE(cond) if(!(cond)) { SK_ABORT(#cond); }
132
133 #ifdef SK_DEBUG
134 #define SkASSERT(cond) SkASSERT_RELEASE(cond)
135 #define SkDEBUGFAIL(message) SkASSERT(false && message)
136 #define SkDEBUGFAILF(fmt, ...) SkASSERTF(false, fmt, ##__VA_ARGS__)
137 #define SkDEBUGCODE(code) code
138 #define SkDECLAREPARAM(type, var) , type var
139 #define SkPARAM(var) , var
140 // #define SkDEBUGF(args ) SkDebugf##args
141 #define SkDEBUGF(args ) SkDebugf args
142 #define SkAssertResult(cond) SkASSERT(cond)
143 #else
144 #define SkASSERT(cond)
145 #define SkDEBUGFAIL(message)
146 #define SkDEBUGCODE(code)
147 #define SkDEBUGF(args)
148 #define SkDECLAREPARAM(type, var)
149 #define SkPARAM(var)
150
151 // unlike SkASSERT, this guy executes its condition in the non-debug build
152 #define SkAssertResult(cond) cond
153 #endif
154
155 // Legacy macro names for SK_ABORT
156 #define SkFAIL(message) SK_ABORT(message)
157 #define sk_throw() SK_ABORT("sk_throw")
158
159 // We want to evaluate cond only once, and inside the SkASSERT somewhere so we see its string form.
160 // So we use the comma operator to make an SkDebugf that always returns false: we'll evaluate cond,
161 // and if it's true the assert passes; if it's false, we'll print the message and the assert fails.
162 #define SkASSERTF(cond, fmt, ...) SkASSERT((cond) || (SkDebugf(fmt"\n", __VA_ARGS__), false))
163
164 #ifdef SK_DEVELOPER
165 #define SkDEVCODE(code) code
166 #else
167 #define SkDEVCODE(code)
168 #endif
169
170 #ifdef SK_IGNORE_TO_STRING
171 #define SK_TO_STRING_NONVIRT()
172 #define SK_TO_STRING_VIRT()
173 #define SK_TO_STRING_PUREVIRT()
174 #define SK_TO_STRING_OVERRIDE()
175 #else
176 class SkString;
177 // the 'toString' helper functions convert Sk* objects to human-readable
178 // form in developer mode
179 #define SK_TO_STRING_NONVIRT() void toString(SkString* str) const;
180 #define SK_TO_STRING_VIRT() virtual void toString(SkString* str) const;
181 #define SK_TO_STRING_PUREVIRT() virtual void toString(SkString* str) const = 0;
182 #define SK_TO_STRING_OVERRIDE() void toString(SkString* str) const override;
183 #endif
184
185 /*
186 * Usage: SK_MACRO_CONCAT(a, b) to construct the symbol ab
187 *
188 * SK_MACRO_CONCAT_IMPL_PRIV just exists to make this work. Do not use directly
189 *
190 */
191 #define SK_MACRO_CONCAT(X, Y) SK_MACRO_CONCAT_IMPL_PRIV(X, Y)
192 #define SK_MACRO_CONCAT_IMPL_PRIV(X, Y) X ## Y
193
194 /*
195 * Usage: SK_MACRO_APPEND_LINE(foo) to make foo123, where 123 is the current
196 * line number. Easy way to construct
197 * unique names for local functions or
198 * variables.
199 */
200 #define SK_MACRO_APPEND_LINE(name) SK_MACRO_CONCAT(name, __LINE__)
201
202 /**
203 * For some classes, it's almost always an error to instantiate one without a name, e.g.
204 * {
205 * SkAutoMutexAcquire(&mutex);
206 * <some code>
207 * }
208 * In this case, the writer meant to hold mutex while the rest of the code in the block runs,
209 * but instead the mutex is acquired and then immediately released. The correct usage is
210 * {
211 * SkAutoMutexAcquire lock(&mutex);
212 * <some code>
213 * }
214 *
215 * To prevent callers from instantiating your class without a name, use SK_REQUIRE_LOCAL_VAR
216 * like this:
217 * class classname {
218 * <your class>
219 * };
220 * #define classname(...) SK_REQUIRE_LOCAL_VAR(classname)
221 *
222 * This won't work with templates, and you must inline the class' constructors and destructors.
223 * Take a look at SkAutoFree and SkAutoMalloc in this file for examples.
224 */
225 #define SK_REQUIRE_LOCAL_VAR(classname) \
226 static_assert(false, "missing name for " #classname)
227
228 ///////////////////////////////////////////////////////////////////////
229
230 /**
231 * Fast type for signed 8 bits. Use for parameter passing and local variables,
232 * not for storage.
233 */
234 typedef int S8CPU;
235
236 /**
237 * Fast type for unsigned 8 bits. Use for parameter passing and local
238 * variables, not for storage
239 */
240 typedef unsigned U8CPU;
241
242 /**
243 * Fast type for signed 16 bits. Use for parameter passing and local variables,
244 * not for storage
245 */
246 typedef int S16CPU;
247
248 /**
249 * Fast type for unsigned 16 bits. Use for parameter passing and local
250 * variables, not for storage
251 */
252 typedef unsigned U16CPU;
253
254 /**
255 * Meant to be a small version of bool, for storage purposes. Will be 0 or 1
256 */
257 typedef uint8_t SkBool8;
258
259 #ifdef SK_DEBUG
260 SK_API int8_t SkToS8(intmax_t);
261 SK_API uint8_t SkToU8(uintmax_t);
262 SK_API int16_t SkToS16(intmax_t);
263 SK_API uint16_t SkToU16(uintmax_t);
264 SK_API int32_t SkToS32(intmax_t);
265 SK_API uint32_t SkToU32(uintmax_t);
266 SK_API int SkToInt(intmax_t);
267 SK_API unsigned SkToUInt(uintmax_t);
268 SK_API size_t SkToSizeT(uintmax_t);
269 #else
270 #define SkToS8(x) ((int8_t)(x))
271 #define SkToU8(x) ((uint8_t)(x))
272 #define SkToS16(x) ((int16_t)(x))
273 #define SkToU16(x) ((uint16_t)(x))
274 #define SkToS32(x) ((int32_t)(x))
275 #define SkToU32(x) ((uint32_t)(x))
276 #define SkToInt(x) ((int)(x))
277 #define SkToUInt(x) ((unsigned)(x))
278 #define SkToSizeT(x) ((size_t)(x))
279 #endif
280
281 /** Returns 0 or 1 based on the condition
282 */
283 #define SkToBool(cond) ((cond) != 0)
284
285 #define SK_MaxS16 32767
286 #define SK_MinS16 -32767
287 #define SK_MaxU16 0xFFFF
288 #define SK_MinU16 0
289 #define SK_MaxS32 0x7FFFFFFF
290 #define SK_MinS32 -SK_MaxS32
291 #define SK_MaxU32 0xFFFFFFFF
292 #define SK_MinU32 0
293 #define SK_NaN32 (1 << 31)
294
295 /** Returns true if the value can be represented with signed 16bits
296 */
SkIsS16(long x)297 static inline bool SkIsS16(long x) {
298 return (int16_t)x == x;
299 }
300
301 /** Returns true if the value can be represented with unsigned 16bits
302 */
SkIsU16(long x)303 static inline bool SkIsU16(long x) {
304 return (uint16_t)x == x;
305 }
306
SkLeftShift(int32_t value,int32_t shift)307 static inline int32_t SkLeftShift(int32_t value, int32_t shift) {
308 return (int32_t) ((uint32_t) value << shift);
309 }
310
SkLeftShift(int64_t value,int32_t shift)311 static inline int64_t SkLeftShift(int64_t value, int32_t shift) {
312 return (int64_t) ((uint64_t) value << shift);
313 }
314
315 //////////////////////////////////////////////////////////////////////////////
316
317 /** Returns the number of entries in an array (not a pointer) */
318 template <typename T, size_t N> char (&SkArrayCountHelper(T (&array)[N]))[N];
319 #define SK_ARRAY_COUNT(array) (sizeof(SkArrayCountHelper(array)))
320
321 // Can be used to bracket data types that must be dense, e.g. hash keys.
322 #if defined(__clang__) // This should work on GCC too, but GCC diagnostic pop didn't seem to work!
323 #define SK_BEGIN_REQUIRE_DENSE _Pragma("GCC diagnostic push") \
324 _Pragma("GCC diagnostic error \"-Wpadded\"")
325 #define SK_END_REQUIRE_DENSE _Pragma("GCC diagnostic pop")
326 #else
327 #define SK_BEGIN_REQUIRE_DENSE
328 #define SK_END_REQUIRE_DENSE
329 #endif
330
331 #define SkAlign2(x) (((x) + 1) >> 1 << 1)
332 #define SkIsAlign2(x) (0 == ((x) & 1))
333
334 #define SkAlign4(x) (((x) + 3) >> 2 << 2)
335 #define SkIsAlign4(x) (0 == ((x) & 3))
336
337 #define SkAlign8(x) (((x) + 7) >> 3 << 3)
338 #define SkIsAlign8(x) (0 == ((x) & 7))
339
340 #define SkAlignPtr(x) (sizeof(void*) == 8 ? SkAlign8(x) : SkAlign4(x))
341 #define SkIsAlignPtr(x) (sizeof(void*) == 8 ? SkIsAlign8(x) : SkIsAlign4(x))
342
343 typedef uint32_t SkFourByteTag;
344 #define SkSetFourByteTag(a, b, c, d) (((a) << 24) | ((b) << 16) | ((c) << 8) | (d))
345
346 /** 32 bit integer to hold a unicode value
347 */
348 typedef int32_t SkUnichar;
349 /** 32 bit value to hold a millisecond count
350 */
351 typedef uint32_t SkMSec;
352 /** 1 second measured in milliseconds
353 */
354 #define SK_MSec1 1000
355 /** maximum representable milliseconds
356 */
357 #define SK_MSecMax 0x7FFFFFFF
358 /** Returns a < b for milliseconds, correctly handling wrap-around from 0xFFFFFFFF to 0
359 */
360 #define SkMSec_LT(a, b) ((int32_t)(a) - (int32_t)(b) < 0)
361 /** Returns a <= b for milliseconds, correctly handling wrap-around from 0xFFFFFFFF to 0
362 */
363 #define SkMSec_LE(a, b) ((int32_t)(a) - (int32_t)(b) <= 0)
364
365 /** The generation IDs in Skia reserve 0 has an invalid marker.
366 */
367 #define SK_InvalidGenID 0
368 /** The unique IDs in Skia reserve 0 has an invalid marker.
369 */
370 #define SK_InvalidUniqueID 0
371
372 /****************************************************************************
373 The rest of these only build with C++
374 */
375 #ifdef __cplusplus
376
377 /** Faster than SkToBool for integral conditions. Returns 0 or 1
378 */
Sk32ToBool(uint32_t n)379 static inline int Sk32ToBool(uint32_t n) {
380 return (n | (0-n)) >> 31;
381 }
382
383 /** Generic swap function. Classes with efficient swaps should specialize this function to take
384 their fast path. This function is used by SkTSort. */
SkTSwap(T & a,T & b)385 template <typename T> inline void SkTSwap(T& a, T& b) {
386 T c(a);
387 a = b;
388 b = c;
389 }
390
SkAbs32(int32_t value)391 static inline int32_t SkAbs32(int32_t value) {
392 SkASSERT(value != SK_NaN32); // The most negative int32_t can't be negated.
393 if (value < 0) {
394 value = -value;
395 }
396 return value;
397 }
398
SkTAbs(T value)399 template <typename T> inline T SkTAbs(T value) {
400 if (value < 0) {
401 value = -value;
402 }
403 return value;
404 }
405
SkMax32(int32_t a,int32_t b)406 static inline int32_t SkMax32(int32_t a, int32_t b) {
407 if (a < b)
408 a = b;
409 return a;
410 }
411
SkMin32(int32_t a,int32_t b)412 static inline int32_t SkMin32(int32_t a, int32_t b) {
413 if (a > b)
414 a = b;
415 return a;
416 }
417
SkTMin(const T & a,const T & b)418 template <typename T> const T& SkTMin(const T& a, const T& b) {
419 return (a < b) ? a : b;
420 }
421
SkTMax(const T & a,const T & b)422 template <typename T> const T& SkTMax(const T& a, const T& b) {
423 return (b < a) ? a : b;
424 }
425
SkSign32(int32_t a)426 static inline int32_t SkSign32(int32_t a) {
427 return (a >> 31) | ((unsigned) -a >> 31);
428 }
429
SkFastMin32(int32_t value,int32_t max)430 static inline int32_t SkFastMin32(int32_t value, int32_t max) {
431 if (value > max) {
432 value = max;
433 }
434 return value;
435 }
436
437 /** Returns value pinned between min and max, inclusively. */
SkTPin(const T & value,const T & min,const T & max)438 template <typename T> static inline const T& SkTPin(const T& value, const T& min, const T& max) {
439 return SkTMax(SkTMin(value, max), min);
440 }
441
442
443 ///////////////////////////////////////////////////////////////////////////////
444
445 /**
446 * Indicates whether an allocation should count against a cache budget.
447 */
448 enum class SkBudgeted : bool {
449 kNo = false,
450 kYes = true
451 };
452
453 ///////////////////////////////////////////////////////////////////////////////
454
455 /** Use to combine multiple bits in a bitmask in a type safe way.
456 */
457 template <typename T>
SkTBitOr(T a,T b)458 T SkTBitOr(T a, T b) {
459 return (T)(a | b);
460 }
461
462 /**
463 * Use to cast a pointer to a different type, and maintaining strict-aliasing
464 */
SkTCast(const void * ptr)465 template <typename Dst> Dst SkTCast(const void* ptr) {
466 union {
467 const void* src;
468 Dst dst;
469 } data;
470 data.src = ptr;
471 return data.dst;
472 }
473
474 //////////////////////////////////////////////////////////////////////////////
475
476 /** \class SkNoncopyable
477
478 SkNoncopyable is the base class for objects that do not want to
479 be copied. It hides its copy-constructor and its assignment-operator.
480 */
481 class SK_API SkNoncopyable {
482 public:
SkNoncopyable()483 SkNoncopyable() {}
484
485 private:
486 SkNoncopyable(const SkNoncopyable&);
487 SkNoncopyable& operator=(const SkNoncopyable&);
488 };
489
490 class SkAutoFree : SkNoncopyable {
491 public:
SkAutoFree()492 SkAutoFree() : fPtr(NULL) {}
SkAutoFree(void * ptr)493 explicit SkAutoFree(void* ptr) : fPtr(ptr) {}
~SkAutoFree()494 ~SkAutoFree() { sk_free(fPtr); }
495
496 /** Return the currently allocate buffer, or null
497 */
get()498 void* get() const { return fPtr; }
499
500 /** Assign a new ptr allocated with sk_malloc (or null), and return the
501 previous ptr. Note it is the caller's responsibility to sk_free the
502 returned ptr.
503 */
set(void * ptr)504 void* set(void* ptr) {
505 void* prev = fPtr;
506 fPtr = ptr;
507 return prev;
508 }
509
510 /** Transfer ownership of the current ptr to the caller, setting the
511 internal reference to null. Note the caller is reponsible for calling
512 sk_free on the returned address.
513 */
detach()514 void* detach() { return this->set(NULL); }
515
516 /** Free the current buffer, and set the internal reference to NULL. Same
517 as calling sk_free(detach())
518 */
free()519 void free() {
520 sk_free(fPtr);
521 fPtr = NULL;
522 }
523
524 private:
525 void* fPtr;
526 // illegal
527 SkAutoFree(const SkAutoFree&);
528 SkAutoFree& operator=(const SkAutoFree&);
529 };
530 #define SkAutoFree(...) SK_REQUIRE_LOCAL_VAR(SkAutoFree)
531
532 /**
533 * Manage an allocated block of heap memory. This object is the sole manager of
534 * the lifetime of the block, so the caller must not call sk_free() or delete
535 * on the block, unless detach() was called.
536 */
537 class SkAutoMalloc : SkNoncopyable {
538 public:
539 explicit SkAutoMalloc(size_t size = 0) {
540 fPtr = size ? sk_malloc_throw(size) : NULL;
541 fSize = size;
542 }
543
~SkAutoMalloc()544 ~SkAutoMalloc() {
545 sk_free(fPtr);
546 }
547
548 /**
549 * Passed to reset to specify what happens if the requested size is smaller
550 * than the current size (and the current block was dynamically allocated).
551 */
552 enum OnShrink {
553 /**
554 * If the requested size is smaller than the current size, and the
555 * current block is dynamically allocated, free the old block and
556 * malloc a new block of the smaller size.
557 */
558 kAlloc_OnShrink,
559
560 /**
561 * If the requested size is smaller than the current size, and the
562 * current block is dynamically allocated, just return the old
563 * block.
564 */
565 kReuse_OnShrink
566 };
567
568 /**
569 * Reallocates the block to a new size. The ptr may or may not change.
570 */
571 void* reset(size_t size, OnShrink shrink = kAlloc_OnShrink, bool* didChangeAlloc = NULL) {
572 if (size == fSize || (kReuse_OnShrink == shrink && size < fSize)) {
573 if (didChangeAlloc) {
574 *didChangeAlloc = false;
575 }
576 return fPtr;
577 }
578
579 sk_free(fPtr);
580 fPtr = size ? sk_malloc_throw(size) : NULL;
581 fSize = size;
582 if (didChangeAlloc) {
583 *didChangeAlloc = true;
584 }
585
586 return fPtr;
587 }
588
589 /**
590 * Releases the block back to the heap
591 */
free()592 void free() {
593 this->reset(0);
594 }
595
596 /**
597 * Return the allocated block.
598 */
get()599 void* get() { return fPtr; }
get()600 const void* get() const { return fPtr; }
601
602 /** Transfer ownership of the current ptr to the caller, setting the
603 internal reference to null. Note the caller is reponsible for calling
604 sk_free on the returned address.
605 */
detach()606 void* detach() {
607 void* ptr = fPtr;
608 fPtr = NULL;
609 fSize = 0;
610 return ptr;
611 }
612
613 private:
614 void* fPtr;
615 size_t fSize; // can be larger than the requested size (see kReuse)
616 };
617 #define SkAutoMalloc(...) SK_REQUIRE_LOCAL_VAR(SkAutoMalloc)
618
619 /**
620 * Manage an allocated block of memory. If the requested size is <= kSizeRequested (or slightly
621 * more), then the allocation will come from the stack rather than the heap. This object is the
622 * sole manager of the lifetime of the block, so the caller must not call sk_free() or delete on
623 * the block.
624 */
625 template <size_t kSizeRequested> class SkAutoSMalloc : SkNoncopyable {
626 public:
627 /**
628 * Creates initially empty storage. get() returns a ptr, but it is to a zero-byte allocation.
629 * Must call reset(size) to return an allocated block.
630 */
SkAutoSMalloc()631 SkAutoSMalloc() {
632 fPtr = fStorage;
633 fSize = kSize;
634 }
635
636 /**
637 * Allocate a block of the specified size. If size <= kSizeRequested (or slightly more), then
638 * the allocation will come from the stack, otherwise it will be dynamically allocated.
639 */
SkAutoSMalloc(size_t size)640 explicit SkAutoSMalloc(size_t size) {
641 fPtr = fStorage;
642 fSize = kSize;
643 this->reset(size);
644 }
645
646 /**
647 * Free the allocated block (if any). If the block was small enough to have been allocated on
648 * the stack, then this does nothing.
649 */
~SkAutoSMalloc()650 ~SkAutoSMalloc() {
651 if (fPtr != (void*)fStorage) {
652 sk_free(fPtr);
653 }
654 }
655
656 /**
657 * Return the allocated block. May return non-null even if the block is of zero size. Since
658 * this may be on the stack or dynamically allocated, the caller must not call sk_free() on it,
659 * but must rely on SkAutoSMalloc to manage it.
660 */
get()661 void* get() const { return fPtr; }
662
663 /**
664 * Return a new block of the requested size, freeing (as necessary) any previously allocated
665 * block. As with the constructor, if size <= kSizeRequested (or slightly more) then the return
666 * block may be allocated locally, rather than from the heap.
667 */
668 void* reset(size_t size,
669 SkAutoMalloc::OnShrink shrink = SkAutoMalloc::kAlloc_OnShrink,
670 bool* didChangeAlloc = NULL) {
671 size = (size < kSize) ? kSize : size;
672 bool alloc = size != fSize && (SkAutoMalloc::kAlloc_OnShrink == shrink || size > fSize);
673 if (didChangeAlloc) {
674 *didChangeAlloc = alloc;
675 }
676 if (alloc) {
677 if (fPtr != (void*)fStorage) {
678 sk_free(fPtr);
679 }
680
681 if (size == kSize) {
682 SkASSERT(fPtr != fStorage); // otherwise we lied when setting didChangeAlloc.
683 fPtr = fStorage;
684 } else {
685 fPtr = sk_malloc_flags(size, SK_MALLOC_THROW | SK_MALLOC_TEMP);
686 }
687
688 fSize = size;
689 }
690 SkASSERT(fSize >= size && fSize >= kSize);
691 SkASSERT((fPtr == fStorage) || fSize > kSize);
692 return fPtr;
693 }
694
695 private:
696 // Align up to 32 bits.
697 static const size_t kSizeAlign4 = SkAlign4(kSizeRequested);
698 #if defined(GOOGLE3)
699 // Stack frame size is limited for GOOGLE3. 4k is less than the actual max, but some functions
700 // have multiple large stack allocations.
701 static const size_t kMaxBytes = 4 * 1024;
702 static const size_t kSize = kSizeRequested > kMaxBytes ? kMaxBytes : kSizeAlign4;
703 #else
704 static const size_t kSize = kSizeAlign4;
705 #endif
706
707 void* fPtr;
708 size_t fSize; // can be larger than the requested size (see kReuse)
709 uint32_t fStorage[kSize >> 2];
710 };
711 // Can't guard the constructor because it's a template class.
712
713 #endif /* C++ */
714
715 #endif
716