Mercurial > sdl-ios-xcode
view src/stdlib/SDL_stdlib.c @ 4139:568c9b3c0167 SDL-1.2
* Added configure option --enable-screensaver, to allow enabling the screensaver by default.
* Use XResetScreenSaver() instead of disabling screensaver entirely.
Full discussion summary from Erik on the SDL mailing list:
Current behaviour
=================
SDL changes the user's display power management settings without
permission from the user and without telling the user.
The interface that it uses to do so is DPMSDisable/DPMSEnable, which
should only ever be used by configuration utilities like KControl, never
by normal application programs, let alone by the libraries that they
use. Using an interface that is not at all intended for what SDL tries
to achieve means that it will not work as it should. Firstly, the power
management is completely disabled during the whole lifetime of the SDL
program, not only when it should be. Secondly, it makes SDL
non-reentrant, meaning that things will break when multiple SDL programs
are clients of the same X server simultaneously. Thirdly, no cleanup
mechanism ensures that the setting is restored if the client does not do
that (for example if it crashes).
In addition to that, this interface is broken on xorg,
[http://bugs.freedesktop.org/show_bug.cgi?id=13962], so what SDL tries
to do does not work at all on that implementation of the X Window
System. (The reason that the DPMSEnable works in KControl is that it
calls DPMSSetTimeout immediately after,
[http://websvn.kde.org/tags/KDE/3.5.9/kdebase/kcontrol/energy/energy.cpp?annotate=774532#l343]).
The problems that the current behaviour causes
==============================================
1. Information leak. When the user is away, someone might see what the
user has on the display when the user counts on the screensaver
preventing this. This does not even require physical access to the
workstation, it is enough to see it from a distance.
2. Draining battery. An SDL program that runs on a laptop will quickly
drain the battery while the user is away. The system will soon shut down
and require recharging before being usable again, while it should in
fact have consumed very little energy if the user's settings would have
been obeyed.
3. Wasting energy. Even if battery issues are not considered, energy as
such is wasted.
4. Display wear. The display may be worn out.
The problems that the current behaviour tries to solve
======================================================
1. Preventing screensaver while playing movies.
Many SDL applications are media players. They have reasons to prevent
screensavers from being activated while a movie is being played. When a
user clicks on the play button it can be interpreted as saying "play
this movie, but do not turn off the display while playing it, because I
will watch it even though I do not interact with the system".
2. Preventing screensaver when some input bypasses X.
Sometimes SDL uses input from another source than the X server, so
that the X server is bypassed. This obviously breaks the screensaver
handling. SDL tries to work around that.
3. Preventing screensaver when all input bypasses X.
There is something called Direct Graphics Access mode, where a
program takes control of both the display and the input devices from the
X server. This obviously means that the X server can not handle the
screensaver alone, since screensaver handling depends on input handling.
SDL does not do what it should to help the X server to handle the
screensaver. Nor does SDL take care of screeensaver handling itself. SDL
simply disables the screensaver completely.
How the problems should be solved
=================================
The correct way for an application program to prevent the screensaver
under X is to call XResetScreenSaver. This was recently discovered and
implemented by the mplayer developers,
[http://svn.mplayerhq.hu/mplayer?view=rev&revision=25637]. SDL needs to
wrap this in an API call (SDL_ResetScreenSaver) and implement it for the
other video targets (if they do not have a corresponding call, SDL
should do what it takes on that particular target, for example sending
fake key events).
1. When a movie is played, the player should reset the screensaver when
the animation is advanced to a new frame. The same applies to anything
similar, like slideshows.
2. When the X server is handling input, it must handle all input
(keyboards, mice, gamepads, ...). This is necessary, not only to be able
to handle the screensaver, but also so that it can send the events to
the correct (the currently active) client. If there is an input device
that the X server can not handle for some reason (such as lack of Plug
and Play capability), the program that handles the device as a
workaround must simulate what would happen if the X server would have
handled the device, by calling XResetScreenSaver when input is received
from the device.
3. When the X server is not handling the input, it depends on the
program that does to call XResetScreenSaver whenever an input event
occurs. Alternatively the program must handle the screensaver countdown
internally and call XActivateScreenSaver.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Fri, 29 Feb 2008 13:55:44 +0000 |
parents | bb6839704ed6 |
children | 782fd950bd46 c121d94672cb a1b03ba2fcd0 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2006 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Sam Lantinga slouken@libsdl.org */ #include "SDL_config.h" /* This file contains portable stdlib functions for SDL */ #include "SDL_stdinc.h" #ifndef HAVE_LIBC /* These are some C runtime intrinsics that need to be defined */ #if defined(_MSC_VER) #ifndef __FLTUSED__ #define __FLTUSED__ #ifdef __cplusplus extern "C" #endif __declspec(selectany) int _fltused=1; #endif /* Float to long */ void __declspec(naked) _ftol() { __asm { push ebp mov ebp,esp sub esp,20h and esp,0FFFFFFF0h fld st(0) fst dword ptr [esp+18h] fistp qword ptr [esp+10h] fild qword ptr [esp+10h] mov edx,dword ptr [esp+18h] mov eax,dword ptr [esp+10h] test eax,eax je integer_QnaN_or_zero arg_is_not_integer_QnaN: fsubp st(1),st test edx,edx jns positive fstp dword ptr [esp] mov ecx,dword ptr [esp] xor ecx,80000000h add ecx,7FFFFFFFh adc eax,0 mov edx,dword ptr [esp+14h] adc edx,0 jmp localexit positive: fstp dword ptr [esp] mov ecx,dword ptr [esp] add ecx,7FFFFFFFh sbb eax,0 mov edx,dword ptr [esp+14h] sbb edx,0 jmp localexit integer_QnaN_or_zero: mov edx,dword ptr [esp+14h] test edx,7FFFFFFFh jne arg_is_not_integer_QnaN fstp dword ptr [esp+18h] fstp dword ptr [esp+18h] localexit: leave ret } } void __declspec(naked) _ftol2_sse() { _ftol(); } /* 64-bit math operators for 32-bit systems */ void __declspec(naked) _allmul() { __asm { push ebp mov ebp,esp push edi push esi push ebx sub esp,0Ch mov eax,dword ptr [ebp+10h] mov edi,dword ptr [ebp+8] mov ebx,eax mov esi,eax sar esi,1Fh mov eax,dword ptr [ebp+8] mul ebx imul edi,esi mov ecx,edx mov dword ptr [ebp-18h],eax mov edx,dword ptr [ebp+0Ch] add ecx,edi imul ebx,edx mov eax,dword ptr [ebp-18h] lea ebx,[ebx+ecx] mov dword ptr [ebp-14h],ebx mov edx,dword ptr [ebp-14h] add esp,0Ch pop ebx pop esi pop edi pop ebp ret } } void __declspec(naked) _alldiv() { __asm { push edi push esi push ebx xor edi,edi mov eax,dword ptr [esp+14h] or eax,eax jge L1 inc edi mov edx,dword ptr [esp+10h] neg eax neg edx sbb eax,0 mov dword ptr [esp+14h],eax mov dword ptr [esp+10h],edx L1: mov eax,dword ptr [esp+1Ch] or eax,eax jge L2 inc edi mov edx,dword ptr [esp+18h] neg eax neg edx sbb eax,0 mov dword ptr [esp+1Ch],eax mov dword ptr [esp+18h],edx L2: or eax,eax jne L3 mov ecx,dword ptr [esp+18h] mov eax,dword ptr [esp+14h] xor edx,edx div ecx mov ebx,eax mov eax,dword ptr [esp+10h] div ecx mov edx,ebx jmp L4 L3: mov ebx,eax mov ecx,dword ptr [esp+18h] mov edx,dword ptr [esp+14h] mov eax,dword ptr [esp+10h] L5: shr ebx,1 rcr ecx,1 shr edx,1 rcr eax,1 or ebx,ebx jne L5 div ecx mov esi,eax mul dword ptr [esp+1Ch] mov ecx,eax mov eax,dword ptr [esp+18h] mul esi add edx,ecx jb L6 cmp edx,dword ptr [esp+14h] ja L6 jb L7 cmp eax,dword ptr [esp+10h] jbe L7 L6: dec esi L7: xor edx,edx mov eax,esi L4: dec edi jne L8 neg edx neg eax sbb edx,0 L8: pop ebx pop esi pop edi ret 10h } } void __declspec(naked) _aulldiv() { __asm { push ebx push esi mov eax,dword ptr [esp+18h] or eax,eax jne L1 mov ecx,dword ptr [esp+14h] mov eax,dword ptr [esp+10h] xor edx,edx div ecx mov ebx,eax mov eax,dword ptr [esp+0Ch] div ecx mov edx,ebx jmp L2 L1: mov ecx,eax mov ebx,dword ptr [esp+14h] mov edx,dword ptr [esp+10h] mov eax,dword ptr [esp+0Ch] L3: shr ecx,1 rcr ebx,1 shr edx,1 rcr eax,1 or ecx,ecx jne L3 div ebx mov esi,eax mul dword ptr [esp+18h] mov ecx,eax mov eax,dword ptr [esp+14h] mul esi add edx,ecx jb L4 cmp edx,dword ptr [esp+10h] ja L4 jb L5 cmp eax,dword ptr [esp+0Ch] jbe L5 L4: dec esi L5: xor edx,edx mov eax,esi L2: pop esi pop ebx ret 10h } } void __declspec(naked) _allrem() { __asm { push ebx push edi xor edi,edi mov eax,dword ptr [esp+10h] or eax,eax jge L1 inc edi mov edx,dword ptr [esp+0Ch] neg eax neg edx sbb eax,0 mov dword ptr [esp+10h],eax mov dword ptr [esp+0Ch],edx L1: mov eax,dword ptr [esp+18h] or eax,eax jge L2 mov edx,dword ptr [esp+14h] neg eax neg edx sbb eax,0 mov dword ptr [esp+18h],eax mov dword ptr [esp+14h],edx L2: or eax,eax jne L3 mov ecx,dword ptr [esp+14h] mov eax,dword ptr [esp+10h] xor edx,edx div ecx mov eax,dword ptr [esp+0Ch] div ecx mov eax,edx xor edx,edx dec edi jns L4 jmp L8 L3: mov ebx,eax mov ecx,dword ptr [esp+14h] mov edx,dword ptr [esp+10h] mov eax,dword ptr [esp+0Ch] L5: shr ebx,1 rcr ecx,1 shr edx,1 rcr eax,1 or ebx,ebx jne L5 div ecx mov ecx,eax mul dword ptr [esp+18h] xchg eax,ecx mul dword ptr [esp+14h] add edx,ecx jb L6 cmp edx,dword ptr [esp+10h] ja L6 jb L7 cmp eax,dword ptr [esp+0Ch] jbe L7 L6: sub eax,dword ptr [esp+14h] sbb edx,dword ptr [esp+18h] L7: sub eax,dword ptr [esp+0Ch] sbb edx,dword ptr [esp+10h] dec edi jns L8 L4: neg edx neg eax sbb edx,0 L8: pop edi pop ebx ret 10h } } void __declspec(naked) _aullrem() { __asm { push ebx mov eax,dword ptr [esp+14h] or eax,eax jne L1 mov ecx,dword ptr [esp+10h] mov eax,dword ptr [esp+0Ch] xor edx,edx div ecx mov eax,dword ptr [esp+8] div ecx mov eax,edx xor edx,edx jmp L2 L1: mov ecx,eax mov ebx,dword ptr [esp+10h] mov edx,dword ptr [esp+0Ch] mov eax,dword ptr [esp+8] L3: shr ecx,1 rcr ebx,1 shr edx,1 rcr eax,1 or ecx,ecx jne L3 div ebx mov ecx,eax mul dword ptr [esp+14h] xchg eax,ecx mul dword ptr [esp+10h] add edx,ecx jb L4 cmp edx,dword ptr [esp+0Ch] ja L4 jb L5 cmp eax,dword ptr [esp+8] jbe L5 L4: sub eax,dword ptr [esp+10h] sbb edx,dword ptr [esp+14h] L5: sub eax,dword ptr [esp+8] sbb edx,dword ptr [esp+0Ch] neg edx neg eax sbb edx,0 L2: pop ebx ret 10h } } void __declspec(naked) _alldvrm() { __asm { push edi push esi push ebp xor edi,edi xor ebp,ebp mov eax,dword ptr [esp+14h] or eax,eax jge L1 inc edi inc ebp mov edx,dword ptr [esp+10h] neg eax neg edx sbb eax,0 mov dword ptr [esp+14h],eax mov dword ptr [esp+10h],edx L1: mov eax,dword ptr [esp+1Ch] or eax,eax jge L2 inc edi mov edx,dword ptr [esp+18h] neg eax neg edx sbb eax,0 mov dword ptr [esp+1Ch],eax mov dword ptr [esp+18h],edx L2: or eax,eax jne L3 mov ecx,dword ptr [esp+18h] mov eax,dword ptr [esp+14h] xor edx,edx div ecx mov ebx,eax mov eax,dword ptr [esp+10h] div ecx mov esi,eax mov eax,ebx mul dword ptr [esp+18h] mov ecx,eax mov eax,esi mul dword ptr [esp+18h] add edx,ecx jmp L4 L3: mov ebx,eax mov ecx,dword ptr [esp+18h] mov edx,dword ptr [esp+14h] mov eax,dword ptr [esp+10h] L5: shr ebx,1 rcr ecx,1 shr edx,1 rcr eax,1 or ebx,ebx jne L5 div ecx mov esi,eax mul dword ptr [esp+1Ch] mov ecx,eax mov eax,dword ptr [esp+18h] mul esi add edx,ecx jb L6 cmp edx,dword ptr [esp+14h] ja L6 jb L7 cmp eax,dword ptr [esp+10h] jbe L7 L6: dec esi sub eax,dword ptr [esp+18h] sbb edx,dword ptr [esp+1Ch] L7: xor ebx,ebx L4: sub eax,dword ptr [esp+10h] sbb edx,dword ptr [esp+14h] dec ebp jns L9 neg edx neg eax sbb edx,0 L9: mov ecx,edx mov edx,ebx mov ebx,ecx mov ecx,eax mov eax,esi dec edi jne L8 neg edx neg eax sbb edx,0 L8: pop ebp pop esi pop edi ret 10h } } void __declspec(naked) _aulldvrm() { __asm { push esi mov eax,dword ptr [esp+14h] or eax,eax jne L1 mov ecx,dword ptr [esp+10h] mov eax,dword ptr [esp+0Ch] xor edx,edx div ecx mov ebx,eax mov eax,dword ptr [esp+8] div ecx mov esi,eax mov eax,ebx mul dword ptr [esp+10h] mov ecx,eax mov eax,esi mul dword ptr [esp+10h] add edx,ecx jmp L2 L1: mov ecx,eax mov ebx,dword ptr [esp+10h] mov edx,dword ptr [esp+0Ch] mov eax,dword ptr [esp+8] L3: shr ecx,1 rcr ebx,1 shr edx,1 rcr eax,1 or ecx,ecx jne L3 div ebx mov esi,eax mul dword ptr [esp+14h] mov ecx,eax mov eax,dword ptr [esp+10h] mul esi add edx,ecx jb L4 cmp edx,dword ptr [esp+0Ch] ja L4 jb L5 cmp eax,dword ptr [esp+8] jbe L5 L4: dec esi sub eax,dword ptr [esp+10h] sbb edx,dword ptr [esp+14h] L5: xor ebx,ebx L2: sub eax,dword ptr [esp+8] sbb edx,dword ptr [esp+0Ch] neg edx neg eax sbb edx,0 mov ecx,edx mov edx,ebx mov ebx,ecx mov ecx,eax mov eax,esi pop esi ret 10h } } void __declspec(naked) _allshl() { __asm { cmp cl,40h jae RETZERO cmp cl,20h jae MORE32 shld edx,eax,cl shl eax,cl ret MORE32: mov edx,eax xor eax,eax and cl,1Fh shl edx,cl ret RETZERO: xor eax,eax xor edx,edx ret } } void __declspec(naked) _aullshr() { __asm { cmp cl,40h jae RETZERO cmp cl,20h jae MORE32 shrd eax,edx,cl shr edx,cl ret MORE32: mov eax,edx xor edx,edx and cl,1Fh shr eax,cl ret RETZERO: xor eax,eax xor edx,edx ret } } #endif /* MSC_VER */ #endif /* !HAVE_LIBC */