embed SDL2gfx.

1 files changed, 189 insertions, 0 deletions

diff --git a/src/sdl2gfx/SDL_framerate.c b/src/sdl2gfx/SDL_framerate.c
new file mode 100644
index 000000000..6735f6355
--- /dev/null
+++ b/src/sdl2gfx/SDL_framerate.c
@@ -0,0 +1,189 @@
+/*
+
+SDL_framerate.c: framerate manager
+
+Copyright (C) 2001-2012  Andreas Schiffler
+
+This software is provided 'as-is', without any express or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not
+claim that you wrote the original software. If you use this software
+in a product, an acknowledgment in the product documentation would be
+appreciated but is not required.
+
+2. Altered source versions must be plainly marked as such, and must not be
+misrepresented as being the original software.
+
+3. This notice may not be removed or altered from any source
+distribution.
+
+Andreas Schiffler -- aschiffler at ferzkopp dot net
+
+*/
+
+#include "SDL_framerate.h"
+
+/*!
+\brief Internal wrapper to SDL_GetTicks that ensures a non-zero return value.
+
+\return The tick count.
+*/
+Uint32 _getTicks()
+{
+	Uint32 ticks = SDL_GetTicks();
+
+	/* 
+	* Since baseticks!=0 is used to track initialization
+	* we need to ensure that the tick count is always >0 
+	* since SDL_GetTicks may not have incremented yet and
+	* return 0 depending on the timing of the calls.
+	*/
+	if (ticks == 0) {
+		return 1;
+	} else {
+		return ticks;
+	}
+}
+
+/*!
+\brief Initialize the framerate manager.
+
+Initialize the framerate manager, set default framerate of 30Hz and
+reset delay interpolation.
+
+\param manager Pointer to the framerate manager.
+*/
+void SDL_initFramerate(FPSmanager * manager)
+{
+	/*
+	* Store some sane values 
+	*/
+	manager->framecount = 0;
+	manager->rate = FPS_DEFAULT;
+	manager->rateticks = (1000.0f / (float) FPS_DEFAULT);
+	manager->baseticks = _getTicks();
+	manager->lastticks = manager->baseticks;
+
+}
+
+/*!
+\brief Set the framerate in Hz 
+
+Sets a new framerate for the manager and reset delay interpolation.
+Rate values must be between FPS_LOWER_LIMIT and FPS_UPPER_LIMIT inclusive to be accepted.
+
+\param manager Pointer to the framerate manager.
+\param rate The new framerate in Hz (frames per second).
+
+\return 0 for sucess and -1 for error.
+*/
+int SDL_setFramerate(FPSmanager * manager, Uint32 rate)
+{
+	if ((rate >= FPS_LOWER_LIMIT) && (rate <= FPS_UPPER_LIMIT)) {
+		manager->framecount = 0;
+		manager->rate = rate;
+		manager->rateticks = (1000.0f / (float) rate);
+		return (0);
+	} else {
+		return (-1);
+	}
+}
+
+/*!
+\brief Return the current target framerate in Hz 
+
+Get the currently set framerate of the manager.
+
+\param manager Pointer to the framerate manager.
+
+\return Current framerate in Hz or -1 for error.
+*/
+int SDL_getFramerate(FPSmanager * manager)
+{
+	if (manager == NULL) {
+		return (-1);
+	} else {
+		return ((int)manager->rate);
+	}
+}
+
+/*!
+\brief Return the current framecount.
+
+Get the current framecount from the framerate manager. 
+A frame is counted each time SDL_framerateDelay is called.
+
+\param manager Pointer to the framerate manager.
+
+\return Current frame count or -1 for error.
+*/
+int SDL_getFramecount(FPSmanager * manager)
+{
+	if (manager == NULL) {
+		return (-1);
+	} else {
+		return ((int)manager->framecount);
+	}
+}
+
+/*!
+\brief Delay execution to maintain a constant framerate and calculate fps.
+
+Generate a delay to accomodate currently set framerate. Call once in the
+graphics/rendering loop. If the computer cannot keep up with the rate (i.e.
+drawing too slow), the delay is zero and the delay interpolation is reset.
+
+\param manager Pointer to the framerate manager.
+
+\return The time that passed since the last call to the function in ms. May return 0.
+*/
+Uint32 SDL_framerateDelay(FPSmanager * manager)
+{
+	Uint32 current_ticks;
+	Uint32 target_ticks;
+	Uint32 the_delay;
+	Uint32 time_passed = 0;
+
+	/*
+	* No manager, no delay
+	*/
+	if (manager == NULL) {
+		return 0;
+	}
+
+	/*
+	* Initialize uninitialized manager 
+	*/
+	if (manager->baseticks == 0) {
+		SDL_initFramerate(manager);
+	}
+
+	/*
+	* Next frame 
+	*/
+	manager->framecount++;
+
+	/*
+	* Get/calc ticks 
+	*/
+	current_ticks = _getTicks();
+	time_passed = current_ticks - manager->lastticks;
+	manager->lastticks = current_ticks;
+	target_ticks = manager->baseticks + (Uint32) ((float) manager->framecount * manager->rateticks);
+
+	if (current_ticks <= target_ticks) {
+		the_delay = target_ticks - current_ticks;
+		SDL_Delay(the_delay);
+	} else {
+		manager->framecount = 0;
+		manager->baseticks = _getTicks();
+	}
+
+	return time_passed;
+}