view docs/html/sdlflip.html @ 3162:dc1eb82ffdaa

Von: Thomas Zimmermann Betreff: [SDL] [PATCH] Make static variables const Datum: Tue, 19 May 2009 19:45:37 +0200 Hi, this is a set of simple changes which make some of SDL's internal static arrays constant. The purpose is to shrink the number of write-able static bytes and thus increase the number of memory pages shared between SDL applications. The patch set is against trunk@4513. Each of the attached patch files is specific to a sub-system. The set is completed by a second mail, because of the list's 40 KiB limit. The files readelf-r4513.txt and readelf-const-patch.txt where made by calling 'readelf -S libSDL.so'. They show the difference in ELF sections without and with the patch. Some numbers measured on my x86-64: Before [13] .rodata PROGBITS 00000000000eaaa0 000eaaa0 0000000000008170 0000000000000000 A 0 0 32 [19] .data.rel.ro PROGBITS 00000000003045e0 001045e0 00000000000023d0 0000000000000000 WA 0 0 32 [23] .data PROGBITS 00000000003076e0 001076e0 0000000000004988 0000000000000000 WA 0 0 32 After [13] .rodata PROGBITS 00000000000eaaa0 000eaaa0 0000000000009a50 0000000000000000 A 0 0 32 [19] .data.rel.ro PROGBITS 0000000000306040 00106040 0000000000002608 0000000000000000 WA 0 0 32 [23] .data PROGBITS 0000000000309360 00109360 0000000000002e88 0000000000000000 WA 0 0 32 The size of the write-able data section decreased considerably. Some entries became const-after-relocation, while most of its content went straight into the read-only data section. Best regards, Thomas
author Sam Lantinga <slouken@libsdl.org>
date Wed, 03 Jun 2009 04:37:27 +0000
parents 355632dca928
children
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>SDL_Flip</H1
><DIV
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><H2
>Name</H2
>SDL_Flip&nbsp;--&nbsp;Swaps screen buffers</DIV
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><PRE
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>#include "SDL.h"</PRE
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><CODE
><CODE
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>int <B
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>SDL_Flip</B
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>(SDL_Surface *screen);</CODE
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><H2
>Description</H2
><P
>On hardware that supports double-buffering, this function sets up a flip
and returns.  The hardware will wait for vertical retrace, and then swap
video buffers before the next video surface blit or lock will return.
On hardware that doesn't support double-buffering, this is equivalent
to calling <A
HREF="sdlupdaterect.html"
>SDL_UpdateRect</A
><TT
CLASS="PARAMETER"
><I
>(screen, 0, 0, 0, 0)</I
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>The <TT
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>SDL_DOUBLEBUF</TT
> flag must have been passed to 
<A
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>SDL_SetVideoMode</A
>,
 when
setting the video mode for this function to perform hardware flipping.</P
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><H2
>Return Value</H2
><P
>This function returns <SPAN
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>0</SPAN
> if successful, or 
<SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> if there was an error.</P
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