scsh-0.6/scsh/sleep1.c

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#include "sysdep.h"
#include <sys/types.h>
#include <sys/time.h>
#if defined(HAVE_SELECT)
# include <sys/types.h> /* for FD_SET and friends (BSD) */
#if defined(HAVE_SYS_SELECT_H)
# include <sys/select.h>
#endif
#endif
#include <unistd.h>
#include <time.h>
#include "../c/scheme48.h"
/* Sleep until time hisecs/losecs (return #t),
** or until interrupted (return #f).
**
** We make you pass in an absolute time so that if you have to loop
** making multiple tries to sleep due to interrupts, you don't get
** drift.
**
** Posix sleep() is not too well defined. This one uses select(),
** and is pretty straightforward.
*/
s48_value sleep_until(s48_value scm_when)
{
time_t now = time(0);
int delta = s48_extract_integer(scm_when) - now;
if( delta > 0 ) {
fd_set r, w, e;
struct timeval tv;
tv.tv_sec = delta;
tv.tv_usec = 0;
FD_ZERO(&r);
FD_ZERO(&w);
FD_ZERO(&e);
if( select(0, &r, &w, &e, &tv) ) return S48_FALSE; /* Lose */
}
return S48_TRUE; /* Win */
}