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Fixed bug #1090 (SDL_BlitCopyOverlap() assumes memcpy() operates in order)

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Even if we're blitting between two different surfaces their pixels might still overlap, because of SDL_CreateRGBSurfaceFrom(), so always use SDL_BlitCopy() and check for overlap in that function.

When handling overlapping surfaces, don't assume that memcpy() iterates forward, instead use memmove() correctly, and provide a fallback implementation of SDL_memmove() that handles the different cases.

Fixed a bug with SDL_memset() not completely filling lengths that aren't a multiple of 4.
Optimized SDL_memcpy() a bit using the same technique as SDL_memset().
This commit is contained in:
Sam Lantinga 2011-02-16 15:25:10 -08:00
parent dc23c42ea9
commit d2b922f555
5 changed files with 76 additions and 111 deletions
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54
include/SDL_stdinc.h
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@ -352,8 +352,8 @@ do { \
#endif
/* We can count on memcpy existing on Mac OS X and being well-tuned. */
#if defined(__MACH__) && defined(__APPLE__)
#define SDL_memcpy(dst, src, len) memcpy(dst, src, len)
#if defined(__MACOSX__)
#define SDL_memcpy memcpy
#elif defined(__GNUC__) && defined(i386)
#define SDL_memcpy(dst, src, len) \
do { \
@ -385,8 +385,8 @@ extern DECLSPEC void *SDLCALL SDL_memcpy(void *dst, const void *src,
#endif
/* We can count on memcpy existing on Mac OS X and being well-tuned. */
#if defined(__MACH__) && defined(__APPLE__)
#define SDL_memcpy4(dst, src, len) memcpy(dst, src, (len)*4)
#if defined(__MACOSX__)
#define SDL_memcpy4(dst, src, len) SDL_memcpy((dst), (src), (len) << 2)
#elif defined(__GNUC__) && defined(i386)
#define SDL_memcpy4(dst, src, len) \
do { \
@ -400,54 +400,14 @@ do { \
} while(0)
#endif
#ifndef SDL_memcpy4
#define SDL_memcpy4(dst, src, len) SDL_memcpy(dst, src, (len) << 2)
#endif
#if defined(__GNUC__) && defined(i386)
#define SDL_revcpy(dst, src, len) \
do { \
int u0, u1, u2; \
char *dstp = SDL_static_cast(char *, dst); \
char *srcp = SDL_static_cast(char *, src); \
int n = (len); \
if ( n >= 4 ) { \
__asm__ __volatile__ ( \
"std\n\t" \
"rep ; movsl\n\t" \
"cld\n\t" \
: "=&c" (u0), "=&D" (u1), "=&S" (u2) \
: "0" (n >> 2), \
"1" (dstp+(n-4)), "2" (srcp+(n-4)) \
: "memory" ); \
} \
switch (n & 3) { \
case 3: dstp[2] = srcp[2]; \
case 2: dstp[1] = srcp[1]; \
case 1: dstp[0] = srcp[0]; \
break; \
default: \
break; \
} \
} while(0)
#endif
#ifndef SDL_revcpy
extern DECLSPEC void *SDLCALL SDL_revcpy(void *dst, const void *src,
size_t len);
#define SDL_memcpy4(dst, src, len) SDL_memcpy((dst), (src), (len) << 2)
#endif
#ifdef HAVE_MEMMOVE
#define SDL_memmove memmove
#elif defined(HAVE_BCOPY)
#define SDL_memmove(d, s, n) bcopy((s), (d), (n))
#else
#define SDL_memmove(dst, src, len) \
do { \
if ( dst < src ) { \
SDL_memcpy(dst, src, len); \
} else { \
SDL_revcpy(dst, src, len); \
} \
} while(0)
extern DECLSPEC void *SDLCALL SDL_memmove(void *dst, const void *src,
size_t len);
#endif
#ifdef HAVE_MEMCMP