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view docs/man3/SDL_CreateCursor.3 @ 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 | 546f7c1eb755 |
children | 1238da4a7112 |
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.TH "SDL_CreateCursor" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_CreateCursor \- Creates a new mouse cursor\&. .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBSDL_Cursor *\fBSDL_CreateCursor\fP\fR(\fBUint8 *data, Uint8 *mask, int w, int h, int hot_x, int hot_y\fR); .SH "DESCRIPTION" .PP Create a cursor using the specified \fBdata\fR and \fBmask\fR (in MSB format)\&. The cursor width must be a multiple of 8 bits\&. .PP The cursor is created in black and white according to the following: .TP 20 \fBData / Mask\fR \fBResulting pixel on screen\fR .TP 20 0 / 1 White .TP 20 1 / 1 Black .TP 20 0 / 0 Transparent .TP 20 1 / 0 Inverted color if possible, black if not\&. .PP Cursors created with this function must be freed with \fISDL_FreeCursor\fR\&. .SH "EXAMPLE" .PP .nf \f(CW/* Stolen from the mailing list */ /* Creates a new mouse cursor from an XPM */ /* XPM */ static const char *arrow[] = { /* width height num_colors chars_per_pixel */ " 32 32 3 1", /* colors */ "X c #000000", "\&. c #ffffff", " c None", /* pixels */ "X ", "XX ", "X\&.X ", "X\&.\&.X ", "X\&.\&.\&.X ", "X\&.\&.\&.\&.X ", "X\&.\&.\&.\&.\&.X ", "X\&.\&.\&.\&.\&.\&.X ", "X\&.\&.\&.\&.\&.\&.\&.X ", "X\&.\&.\&.\&.\&.\&.\&.\&.X ", "X\&.\&.\&.\&.\&.XXXXX ", "X\&.\&.X\&.\&.X ", "X\&.X X\&.\&.X ", "XX X\&.\&.X ", "X X\&.\&.X ", " X\&.\&.X ", " X\&.\&.X ", " X\&.\&.X ", " XX ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", "0,0" }; static SDL_Cursor *init_system_cursor(const char *image[]) { int i, row, col; Uint8 data[4*32]; Uint8 mask[4*32]; int hot_x, hot_y; i = -1; for ( row=0; row<32; ++row ) { for ( col=0; col<32; ++col ) { if ( col % 8 ) { data[i] <<= 1; mask[i] <<= 1; } else { ++i; data[i] = mask[i] = 0; } switch (image[4+row][col]) { case \&'X\&': data[i] |= 0x01; k[i] |= 0x01; break; case \&'\&.\&': mask[i] |= 0x01; break; case \&' \&': break; } } } sscanf(image[4+row], "%d,%d", &hot_x, &hot_y); return SDL_CreateCursor(data, mask, 32, 32, hot_x, hot_y); }\fR .fi .PP .SH "SEE ALSO" .PP \fI\fBSDL_FreeCursor\fP\fR, \fI\fBSDL_SetCursor\fP\fR, \fI\fBSDL_ShowCursor\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01