Add RISC-V port for newlib

  Contributor list:
    - Andrew Waterman  <andrew@sifive.com>
    - Palmer Dabbelt  <palmer@dabbelt.com>
    - Kito Cheng  <kito.cheng@gmail.com>
    - Scott Beamer  <sbeamer@eecs.berkeley.edu>

1 files changed, 32 insertions, 0 deletions

diff --git a/newlib/libc/machine/riscv/ffs.c b/newlib/libc/machine/riscv/ffs.c
new file mode 100644
index 000000000..652207722
--- /dev/null
+++ b/newlib/libc/machine/riscv/ffs.c
@@ -0,0 +1,32 @@
+/* Copyright (c) 2017  SiFive Inc. All rights reserved.
+
+   This copyrighted material is made available to anyone wishing to use,
+   modify, copy, or redistribute it subject to the terms and conditions
+   of the BSD License.   This program is distributed in the hope that
+   it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
+   including the implied warranties of MERCHANTABILITY or FITNESS FOR
+   A PARTICULAR PURPOSE.  A copy of this license is available at
+   http://www.opensource.org/licenses.
+*/
+#include <strings.h>
+
+int
+ffs (int word)
+{
+#if __riscv_xlen == 32
+  return (__builtin_ffs (word));
+#else
+  int i;
+
+  if (!word)
+    return 0;
+
+  i = 0;
+  for (;;)
+    {
+      if (((1 << i++) & word) != 0)
+       return i;
+    }
+  return 0;
+#endif
+}