[Xen-devel] [PATCH] minios: implement ffs, ffsl, ffsll

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Hi all,
this patch implements ffs, ffsl and ffsll.
The first function is compiled only in case minios is compiled without
newlib, since newlib already provides an implementation for ffs.
On the other hand ffsl and ffsll are always compiled because newlib misses
those functions.
This patch also provides an implementation for __ffsti2 and __ffsdi2
because they are needed by gcc in order to successfully link ffsll.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

---


diff -r f0e2df69a8eb extras/mini-os/include/posix/strings.h
--- a/extras/mini-os/include/posix/strings.h    Tue May 26 15:01:36 2009 +0100
+++ b/extras/mini-os/include/posix/strings.h    Wed May 27 17:31:43 2009 +0100
@@ -5,4 +5,8 @@
 
 #define bzero(ptr, size) (memset((ptr), '\0', (size)), (void) 0)
 
+int ffs (int i);
+int ffsl (long int li);
+int ffsll (long long int lli);
+
 #endif /* _POSIX_STRINGS_H */
diff -r f0e2df69a8eb extras/mini-os/lib/string.c
--- a/extras/mini-os/lib/string.c       Tue May 26 15:01:36 2009 +0100
+++ b/extras/mini-os/lib/string.c       Wed May 27 17:31:43 2009 +0100
@@ -17,6 +17,43 @@
  * $Id: c-insert.c,v 1.7 2002/11/08 16:04:34 rn Exp $
  ****************************************************************************
  */
+
+#include <strings.h>
+
+/* newlib defines ffs but not ffsll or ffsl */
+int __ffsti2 (long long int lli)
+{
+    int i, num, t, tmpint, len;
+
+    num = sizeof(long long int) / sizeof(int);
+    if (num == 1) return (ffs((int) lli));
+    len = sizeof(int) * 8;
+
+    for (i = 0; i < num; i++) {
+        tmpint = (int) (((lli >> len) << len) ^ lli);
+
+        t = ffs(tmpint);
+        if (t)
+            return (t + i * len);
+        lli = lli >> len;
+    }
+    return 0;
+}
+
+int __ffsdi2 (long int li)
+{
+    return __ffsti2 ((long long int) li);
+}
+
+int ffsl (long int li)
+{
+    return __ffsti2 ((long long int) li);
+}
+
+int ffsll (long long int lli)
+{
+    return __ffsti2 (lli);
+}
 
 #if !defined HAVE_LIBC
 
@@ -175,4 +212,17 @@
     return res;
 }
 
+int ffs(int i)
+{
+   int c = 1;
+
+   do {
+      if (i & 1)
+         return (c);
+      i = i >> 1;
+      c++;
+   } while (i);
+   return 0;
+}
+
 #endif

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