source: bootcd/isolinux/syslinux-6.03/gpxe/src/include/unistd.h

#ifndef _UNISTD_H
#define _UNISTD_H

FILE_LICENCE ( GPL2_OR_LATER );

#include <stddef.h>
#include <stdarg.h>

extern int execv ( const char *command, char * const argv[] );

/**
 * Execute command
 *
 * @v command           Command name
 * @v arg ...           Argument list (starting with argv[0])
 * @ret rc              Command exit status
 *
 * This is a front end to execv().
 */
#define execl( command, arg, ... ) ( {                                  \
                char * const argv[] = { (arg), ## __VA_ARGS__ };        \
                int rc = execv ( (command), argv );                     \
                rc;                                                     \
        } )

/* Pick up udelay() */
#include <gpxe/timer.h>

/*
 * sleep() prototype is defined by POSIX.1.  usleep() prototype is
 * defined by 4.3BSD.  udelay() and mdelay() prototypes are chosen to
 * be reasonably sensible.
 *
 */

extern unsigned int sleep ( unsigned int seconds );
extern void mdelay ( unsigned long msecs );

static inline __always_inline void usleep ( unsigned long usecs ) {
        udelay ( usecs );
}

#endif /* _UNISTD_H */