libxc: Define xc_ffs{8,16,32,64} functions. Use them.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/tools/libxc/xc_private.c b/tools/libxc/xc_private.c
index 5990415d9e..e0613b9e4f 100644
--- a/tools/libxc/xc_private.c
+++ b/tools/libxc/xc_private.c
@@ -639,6 +639,33 @@ int write_exact(int fd, const void *data, size_t size)
     return 0;
 }
 
+int xc_ffs8(uint8_t x)
+{
+    int i;
+    for ( i = 0; i < 8; i++ )
+        if ( x & (1u << i) )
+            return i+1;
+    return 0;
+}
+
+int xc_ffs16(uint16_t x)
+{
+    uint8_t h = x>>8, l = x;
+    return l ? xc_ffs8(l) : h ? xc_ffs8(h) + 8 : 0;
+}
+
+int xc_ffs32(uint32_t x)
+{
+    uint16_t h = x>>16, l = x;
+    return l ? xc_ffs16(l) : h ? xc_ffs16(h) + 16 : 0;
+}
+
+int xc_ffs64(uint64_t x)
+{
+    uint32_t h = x>>32, l = x;
+    return l ? xc_ffs32(l) : h ? xc_ffs32(h) + 32 : 0;
+}
+
 /*
  * Local variables:
  * mode: C