48 lines
812 B
C
48 lines
812 B
C
/*
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* sleep - suspend current process for a number of seconds
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*/
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/* $Header$ */
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#include <signal.h>
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#include <setjmp.h>
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int alarm(int n);
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void pause(void);
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static jmp_buf setjmpbuf;
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static void
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alfun(int sig)
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{
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longjmp(setjmpbuf, 1);
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} /* used with sleep() below */
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void
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sleep(int n)
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{
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/* sleep(n) pauses for 'n' seconds by scheduling an alarm interrupt. */
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unsigned oldalarm;
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void (*oldsig)(int);
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if (n <= 0) return;
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if (setjmp(setjmpbuf)) {
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signal(SIGALRM, oldsig);
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alarm(oldalarm);
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return;
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}
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oldalarm = alarm(5000); /* Who cares how long, as long
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* as it is long enough
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*/
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if (oldalarm > n) oldalarm -= n;
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else if (oldalarm) {
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n = oldalarm;
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oldalarm = 1;
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}
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oldsig = signal(SIGALRM, alfun);
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alarm(n);
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for (;;) {
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/* allow for other handlers ... */
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pause();
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}
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}
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