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

--- a/src/events/scancodes_xfree86.h	Sun May 31 11:53:12 2009 +0000
+++ b/src/events/scancodes_xfree86.h	Wed Jun 03 04:37:27 2009 +0000
@@ -26,7 +26,7 @@
    - atKeyNames.h from XFree86 source code
 */
 /* *INDENT-OFF* */
-static SDL_scancode xfree86_scancode_table[] = {
+static const SDL_scancode xfree86_scancode_table[] = {
     /*  0 */    SDL_SCANCODE_UNKNOWN,
     /*  1 */    SDL_SCANCODE_ESCAPE,
     /*  2 */    SDL_SCANCODE_1,
@@ -177,7 +177,7 @@
 };
 
 /* for wireless usb keyboard (manufacturer TRUST) without numpad. */
-static SDL_scancode xfree86_scancode_table2[] = {
+static const SDL_scancode xfree86_scancode_table2[] = {
     /*  0 */    SDL_SCANCODE_UNKNOWN,
     /*  1 */    SDL_SCANCODE_ESCAPE,
     /*  2 */    SDL_SCANCODE_1,