mirror of https://github.com/marqs85/ossc.git
70 lines
2.3 KiB
C
70 lines
2.3 KiB
C
/*
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* Copyright (c) 2003-2004 Altera Corporation, San Jose, California, USA.
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* All rights reserved.
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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
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* DEALINGS IN THE SOFTWARE.
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*
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* ------------
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*
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* Altera does not recommend, suggest or require that this reference design
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* file be used in conjunction or combination with any other product.
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*
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* alt_busy_sleep.c - Microsecond delay routine which uses a calibrated busy
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* loop to perform the delay. This is used to implement
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* usleep for both uC/OS-II and the standalone HAL.
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*
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* Author PRR
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*
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* Calibrated delay with no timer required
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*
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* The ASM instructions in the routine are equivalent to
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*
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* for (i=0;i<us*(ALT_CPU_FREQ/3);i++);
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*
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* and takes three cycles each time around the loop
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*
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*/
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#include <limits.h>
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#include <string.h>
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#include "system.h"
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#include "alt_types.h"
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#include "priv/alt_busy_sleep.h"
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unsigned int alt_busy_sleep (unsigned int us)
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{
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/*
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* Only delay if ALT_SIM_OPTIMIZE is not defined; i.e., if software
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* is built targetting ModelSim RTL simulation, the delay will be
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* skipped to speed up simulation.
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*/
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#ifndef ALT_SIM_OPTIMIZE
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unsigned long i, loops;
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// 1 loop >= 7 cyc
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loops = ((ALT_CPU_FREQ/1000000)*us)/7;
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for (i=7; i<loops; i++)
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asm volatile ("nop");
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#endif /* #ifndef ALT_SIM_OPTIMIZE */
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return 0;
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}
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