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Implement '_nanosleep()' 

This patch provides an implementation of the '_nanosleep()' libc function,
which blocks on a timed semaphore for the given time, but at least 10ms.
This should result in better performance than creating a timer connection
on every call (for thread-safety), but could still be improved.

Fixes #158.
This commit is contained in:
Christian Prochaska 2012-03-20 16:57:58 +01:00 committed by Norman Feske
parent 983ee6321a
commit 12e1ae9d72
3 changed files with 42 additions and 2 deletions
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2
libports/lib/mk/libc.mk
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@ -12,7 +12,7 @@ LIBS += timed_semaphore cxx
SRC_CC = atexit.cc dummies.cc rlimit.cc sysctl.cc readlink.cc munmap.cc \
issetugid.cc errno.cc gai_strerror.cc clock_gettime.cc \
gettimeofday.cc malloc.cc progname.cc fd_alloc.cc file_operations.cc \
plugin.cc plugin_registry.cc select.cc exit.cc environ.cc
plugin.cc plugin_registry.cc select.cc exit.cc environ.cc nanosleep.cc
#
# Files from string library that are not included in libc-raw_string because

1
libports/src/lib/libc/dummies.cc
View File

@ -86,7 +86,6 @@ DUMMY(-1, mkfifo)
DUMMY(-1, mknod)
DUMMY(-1, mprotect)
DUMMY(-1, nanosleep)
DUMMY(-1, _nanosleep)
DUMMY(-1, __nsdefaultsrc)
DUMMY(-1, _nsdispatch)
DUMMY(-1, _openat)

41
libports/src/lib/libc/nanosleep.cc Normal file
View File

@ -0,0 +1,41 @@
/*
* \brief C-library back end
* \author Christian Prochaska
* \date 2012-03-20
*/
/*
* Copyright (C) 2008-2012 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#include <os/timed_semaphore.h>
#include <sys/time.h>
using namespace Genode;
extern "C" __attribute__((weak))
int _nanosleep(const struct timespec *req, struct timespec *rem)
{
Genode::Alarm::Time sleep_msec = (req->tv_sec * 1000) + (req->tv_nsec / 1000000);
/* Timed_semaphore does not support timeouts < 10ms */
if (sleep_msec < 10)
sleep_msec = 10;
Timed_semaphore sem(0);
try {
sem.down(sleep_msec);
} catch(Timeout_exception) {
}
if (rem) {
rem->tv_sec = 0;
rem->tv_nsec = 0;
}
return 0;
}