66 lines
1.2 KiB
C
66 lines
1.2 KiB
C
/*
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* Raspberry Pi support library for the ACK
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* © 2013 David Given
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* This file is redistributable under the terms of the 3-clause BSD license.
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* See the file 'Copying' in the root of the distribution for the full text.
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*/
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#include <stdlib.h>
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#include <errno.h>
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#include <unistd.h>
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#include <sys/select.h>
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#include <time.h>
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#include <pi.h>
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#include "libsys.h"
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#define TICKS_PER_SEC 1000000
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typedef int condition_t(void);
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static int nop_condition(void)
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{
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return 0;
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}
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int select(int nfds, fd_set *readfds, fd_set *writefds,
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fd_set *exceptfds, struct timeval *timeout)
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{
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int result = 0;
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condition_t* condition = nop_condition;
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if (FD_ISSET(0, readfds))
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condition = _sys_rawpoll;
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FD_ZERO(readfds);
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FD_ZERO(writefds);
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FD_ZERO(exceptfds);
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if (timeout)
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{
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/* Wait for a specified amount of time. */
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uint32_t ticks = (timeout->tv_sec * TICKS_PER_SEC) +
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(timeout->tv_usec * (TICKS_PER_SEC/1000000));
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uint32_t* timer_clo = pi_phys_to_user((void*) 0x7e003004);
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uint32_t ra = *timer_clo;
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while (!condition() && ((*timer_clo - ra) < ticks))
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;
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}
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else
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{
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/* Wait forever. */
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while (!condition())
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;
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}
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if ((condition == _sys_rawpoll) && condition())
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{
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FD_SET(0, readfds);
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result = 1;
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}
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return result;
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}
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