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/*
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* High-resolution timing routines (PIT reprogramming)
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*
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* This file is part of the Mateusz' DOS Routines (MDR): http://mdr.osdn.io
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* Published under the terms of the MIT License, as stated below.
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*
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* Copyright (C) 2014-2023 Mateusz Viste
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#ifndef MDR_TIMER_H
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#define MDR_TIMER_H
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/* Starts the timer by reprogramming the 8253 chip from its default 18.2 Hz
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* frequency to about 1.1 kHz. It is mandatory to revert the timer to its
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* original frequency via mdr_timer_stop() before your application quits. */
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void mdr_timer_init(void);
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/* Fills res with the amount of microseconds that elapsed since either
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* mdr_timer_init() or mdr_timer_reset(), whichever was called last.
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* Note that the res counter wraps around approximately every 71 minutes if
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* mdr_timer_reset() is not called. */
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void mdr_timer_read(unsigned long *res);
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/* Reset the timer value, this can be used by the application to make sure
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* no timer wrap occurs during critical parts of your code flow */
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void mdr_timer_reset(void);
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/* Stops (uninstalls) the timer. This must be called before your application
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* quits, otherwise the system will likely crash. This function has a void
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* return value so that it can be registered as an atexit() procedure. */
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void mdr_timer_stop(void);
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#endif
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