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rubidium

(svn r17776) -Codechange: [SDL] make "update the video card"-process asynchronious. Profiling with gprof etc. hasn't shown us that DrawSurfaceToScreen takes a significant amount of CPU; only using TIC/TOC it became apparant that it was a heavy CPU-cycle user or that it was waiting for something.
The benefit of making this function asynchronious ranges from 2%-25% (real time) during fast forward on dual core/hyperthreading-enabled CPUs; 8bpp improvements are, in my test cases, significantly smaller than 32bpp improvements.
On single core non-hyperthreading-enabled CPUs the extra locking/scheduling costs up to 1% extra realtime in fast forward. You can use -v sdl:no_threads to disable threading and undo this loss.
During normal non-fast-forwarded games the benefit/costs are negligable except when the gameloop takes more than about 90% of the time of a tick.
Note that allegro's performance does not improve with this system, likely due to their way of getting data to the video card. It is not implemented for the OS X/Windows video backends, unless (ofcourse) SDL is used there.
Funny is that the performance of the 32bpp(-anim) blitter is, at least in some test cases, significantly faster (more than 10%) than the 8bpp(-optimized) blitter when looking at real time in fast forward on a dual core CPU; it was slower.
The idea comes from a paper/report by Idar Borlaug and Knut Imar Hagen.

/* $Id$ */

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD 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 General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file variables.h Messing file that will cease to exist some time in the future. */

#ifndef VARIABLES_H
#define VARIABLES_H

#ifndef VARDEF
#define VARDEF extern
#endif

/* Amount of game ticks */
VARDEF uint16 _tick_counter;

/* Also save scrollpos_x, scrollpos_y and zoom */
VARDEF uint16 _disaster_delay;

/* Determines how often to run the tree loop */
VARDEF byte _trees_tick_ctr;

/* NOSAVE: Used in palette animations only, not really important. */
VARDEF int _palette_animation_counter;

VARDEF uint32 _realtime_tick;

VARDEF bool _do_autosave;

VARDEF byte _display_opt;

VARDEF bool _rightclick_emulate;

/* IN/OUT parameters to commands */
VARDEF bool _generating_world;

VARDEF char *_config_file;
VARDEF char *_highscore_file;
VARDEF char *_log_file;

/* landscape.cpp */
extern const byte _tileh_to_sprite[32];

/* Forking stuff */
VARDEF bool _dedicated_forks;

#endif /* VARIABLES_H */