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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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<HTML ><HEAD ><TITLE >SDL_CDOpen</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="CD-ROM" HREF="cdrom.html"><LINK REL="PREVIOUS" TITLE="SDL_CDName" HREF="sdlcdname.html"><LINK REL="NEXT" TITLE="SDL_CDStatus" HREF="sdlcdstatus.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdlcdname.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlcdstatus.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLCDOPEN" ></A >SDL_CDOpen</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN7274" ></A ><H2 >Name</H2 >SDL_CDOpen -- Opens a CD-ROM drive for access.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN7277" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN7278" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >SDL_CD *<B CLASS="FSFUNC" >SDL_CDOpen</B ></CODE >(int drive);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN7284" ></A ><H2 >Description</H2 ><P >Opens a CD-ROM drive for access. It returns a <A HREF="sdlcd.html" ><SPAN CLASS="STRUCTNAME" >SDL_CD</SPAN ></A > structure on success, or <TT CLASS="LITERAL" >NULL</TT > if the drive was invalid or busy. This newly opened CD-ROM becomes the default CD used when other CD functions are passed a <TT CLASS="LITERAL" >NULL</TT > CD-ROM handle. </P ><P >Drives are numbered starting with 0. Drive 0 is the system default CD-ROM.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN7292" ></A ><H2 >Examples</H2 ><PRE CLASS="PROGRAMLISTING" >SDL_CD *cdrom; int cur_track; int min, sec, frame; SDL_Init(SDL_INIT_CDROM); atexit(SDL_Quit); /* Check for CD drives */ if(!SDL_CDNumDrives()){ /* None found */ fprintf(stderr, "No CDROM devices available\n"); exit(-1); } /* Open the default drive */ cdrom=SDL_CDOpen(0); /* Did if open? Check if cdrom is NULL */ if(!cdrom){ fprintf(stderr, "Couldn't open drive: %s\n", SDL_GetError()); exit(-1); } /* Print Volume info */ printf("Name: %s\n", SDL_CDName(0)); printf("Tracks: %d\n", cdrom->numtracks); for(cur_track=0;cur_track < cdrom->numtracks; cur_track++){ FRAMES_TO_MSF(cdrom->track[cur_track].length, &min, &sec, &frame); printf("\tTrack %d: Length %d:%d\n", cur_track, min, sec); } SDL_CDClose(cdrom);</PRE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN7295" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlcd.html" ><SPAN CLASS="STRUCTNAME" >SDL_CD</SPAN ></A >, <A HREF="sdlcdtrack.html" ><SPAN CLASS="STRUCTNAME" >SDL_CDtrack</SPAN ></A >, <A HREF="sdlcdclose.html" ><TT CLASS="FUNCTION" >SDL_CDClose</TT ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdlcdname.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlcdstatus.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_CDName</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="cdrom.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_CDStatus</TD ></TR ></TABLE ></DIV ></BODY ></HTML >