Add SDL_SIMDRealloc

Ethan Lee 2020-06-11 12:03:33 -04:00
parent 20aada0efc
commit 2aa8974f97
4 changed files with 78 additions and 0 deletions

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@ -246,10 +246,33 @@ extern DECLSPEC size_t SDLCALL SDL_SIMDGetAlignment(void);
* \return Pointer to newly-allocated block, NULL if out of memory.
*
* \sa SDL_SIMDAlignment
* \sa SDL_SIMDRealloc
* \sa SDL_SIMDFree
*/
extern DECLSPEC void * SDLCALL SDL_SIMDAlloc(const size_t len);
/**
* \brief Reallocate memory obtained from SDL_SIMDAlloc
*
* It is not valid to use this function on a pointer from anything but
* SDL_SIMDAlloc(). It can't be used on pointers from malloc, realloc,
* SDL_malloc, memalign, new[], etc.
*
* \param mem The pointer obtained from SDL_SIMDAlloc. This function also
* accepts NULL, at which point this function is the same as
* calling SDL_realloc with a NULL pointer.
* \param len The length, in bytes, of the block to allocated. The actual
* allocated block might be larger due to padding, etc. Passing 0
* will return a non-NULL pointer, assuming the system isn't out of
* memory.
* \return Pointer to newly-reallocated block, NULL if out of memory.
*
* \sa SDL_SIMDAlignment
* \sa SDL_SIMDAlloc
* \sa SDL_SIMDFree
*/
extern DECLSPEC void * SDLCALL SDL_SIMDRealloc(void *mem, size_t len);
/**
* \brief Deallocate memory obtained from SDL_SIMDAlloc
*
@ -260,6 +283,7 @@ extern DECLSPEC void * SDLCALL SDL_SIMDAlloc(const size_t len);
* However, SDL_SIMDFree(NULL) is a legal no-op.
*
* \sa SDL_SIMDAlloc
* \sa SDL_SIMDRealloc
*/
extern DECLSPEC void SDLCALL SDL_SIMDFree(void *ptr);

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@ -956,6 +956,58 @@ SDL_SIMDAlloc(const size_t len)
return retval;
}
void *
SDL_SIMDRealloc(void *mem, const size_t len)
{
const size_t alignment = SDL_SIMDGetAlignment();
const size_t padding = alignment - (len % alignment);
const size_t padded = (padding != alignment) ? (len + padding) : len;
Uint8 *retval = (Uint8*) mem;
void *oldmem = mem;
size_t memdiff, ptrdiff;
Uint8 *ptr;
if (mem) {
void **realptr = (void **) mem;
realptr--;
mem = *(((void **) mem) - 1);
/* Check the delta between the real pointer and user pointer */
memdiff = ((size_t) oldmem) - ((size_t) mem);
}
ptr = (Uint8 *) SDL_realloc(mem, padded + alignment + sizeof (void *));
if (ptr == mem) {
return retval; /* Pointer didn't change, nothing to do */
}
if (ptr == NULL) {
return NULL; /* Out of memory, bail! */
}
/* Store the actual malloc pointer right before our aligned pointer. */
retval = ptr + sizeof (void *);
retval += alignment - (((size_t) retval) % alignment);
/* Make sure the delta is the same! */
if (mem) {
ptrdiff = ((size_t) retval) - ((size_t) ptr);
if (memdiff != ptrdiff) { /* Delta has changed, copy to new offset! */
oldmem = (void*) (((size_t) ptr) + memdiff);
/* Even though the data past the old `len` is undefined, this is the
* only length value we have, and it guarantees that we copy all the
* previous memory anyhow.
*/
SDL_memmove(retval, oldmem, len);
}
}
/* Actually store the malloc pointer, finally. */
*(((void **) retval) - 1) = ptr;
return retval;
}
void
SDL_SIMDFree(void *ptr)
{

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@ -716,6 +716,7 @@
#define SDL_UIKitRunApp SDL_UIKitRunApp_REAL
#define SDL_SIMDGetAlignment SDL_SIMDGetAlignment_REAL
#define SDL_SIMDAlloc SDL_SIMDAlloc_REAL
#define SDL_SIMDRealloc SDL_SIMDRealloc_REAL
#define SDL_SIMDFree SDL_SIMDFree_REAL
#define SDL_RWsize SDL_RWsize_REAL
#define SDL_RWseek SDL_RWseek_REAL

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@ -772,6 +772,7 @@ SDL_DYNAPI_PROC(int,SDL_UIKitRunApp,(int a, char *b, SDL_main_func c),(a,b,c),re
#endif
SDL_DYNAPI_PROC(size_t,SDL_SIMDGetAlignment,(void),(),return)
SDL_DYNAPI_PROC(void*,SDL_SIMDAlloc,(const size_t a),(a),return)
SDL_DYNAPI_PROC(void*,SDL_SIMDRealloc,(void *a, const size_t b),(a, b),return)
SDL_DYNAPI_PROC(void,SDL_SIMDFree,(void *a),(a),)
SDL_DYNAPI_PROC(Sint64,SDL_RWsize,(SDL_RWops *a),(a),return)
SDL_DYNAPI_PROC(Sint64,SDL_RWseek,(SDL_RWops *a, Sint64 b, int c),(a,b,c),return)