Add replacement for GNU ffsll()

compat/ffsll.c

+/*****************************************************************************
+ * ffsllp.c: GNU ffsll() replacement
+ *****************************************************************************
+ * Copyright © 2015 Rémi Denis-Courmont
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <limits.h>
+
+int ffsll(unsigned long long x)
+{
+    for (unsigned i = 0; i < sizeof (x) * CHAR_BIT; i++)
+        if ((x >> i) & 1)
+            return i + 1;
+    return 0;
+}

configure.ac

@@ -554,7 +554,7 @@ need_libc=false
 dnl Check for usual libc functions
 AC_CHECK_DECLS([nanosleep],,,[#include <time.h>])
 AC_CHECK_FUNCS([daemon fcntl fstatvfs fork getenv getpwuid_r isatty lstat memalign mmap open_memstream openat pread posix_fadvise posix_madvise setlocale stricmp strnicmp strptime uselocale pthread_cond_timedwait_monotonic_np pthread_condattr_setclock])
-AC_REPLACE_FUNCS([atof atoll dirfd fdopendir flockfile fsync getdelim getpid lldiv nrand48 poll posix_memalign rewind setenv strcasecmp strcasestr strdup strlcpy strndup strnlen strsep strtof strtok_r strtoll swab tdestroy strverscmp])
+AC_REPLACE_FUNCS([atof atoll dirfd fdopendir ffsll flockfile fsync getdelim getpid lldiv nrand48 poll posix_memalign rewind setenv strcasecmp strcasestr strdup strlcpy strndup strnlen strsep strtof strtok_r strtoll swab tdestroy strverscmp])
 AC_CHECK_FUNCS(fdatasync,,
   [AC_DEFINE(fdatasync, fsync, [Alias fdatasync() to fsync() if missing.])
 ])

include/vlc_fixups.h

@@ -120,6 +120,10 @@ int vasprintf (char **, const char *, va_list);
 #endif
 
 /* string.h */
+#ifndef HAVE_FFSLL
+int ffsll(unsigned long long);
+#endif
+
 #ifndef HAVE_STRCASECMP
 int strcasecmp (const char *, const char *);
 #endif