1 files changed, 87 insertions, 0 deletions
diff --git a/viengoos/bits.h b/viengoos/bits.h
new file mode 100644
index 0000000..22823e3
--- /dev/null
+++ b/viengoos/bits.h
@@ -0,0 +1,87 @@
+/* bits.h - Bit manipulation functions.
+   Copyright (C) 2007 Free Software Foundation, Inc.
+   Written by Neal H. Walfield <neal@gnu.org>.
+
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 3 of the
+   License, or (at your option) any later version.
+
+   The GNU Hurd 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
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef RM_BITS_H
+#define RM_BITS_H
+
+#include <stdint.h>
+#include <assert.h>
+
+/* Return the C bits of word W starting a bit S.  (The LSB is 0 and
+   the MSB is L4_WORDSIZE.)  */
+static inline unsigned int
+extract_bits (unsigned int w, int s, int c)
+{
+  assert (0 <= s && s < (sizeof (unsigned int) * 8));
+  assert (0 <= c && s + c <= (sizeof (unsigned int) * 8));
+
+  if (c == (sizeof (unsigned int) * 8))
+    /* 1U << (sizeof (unsigned int) * 8) is problematic: "If the value of
+       the right operand is negative or is greater than or equal to
+       the width of the promoted left operand, the behavior is
+       undefined."  */
+    {
+      assert (s == 0);
+      return w;
+    }
+  else
+    return (w >> s) & ((1ULL << c) - 1);
+}
+
+static inline uint64_t
+extract_bits64 (uint64_t w, int s, int c)
+{
+  assert (0 <= s && s < (sizeof (uint64_t) * 8));
+  assert (0 <= c && s + c <= (sizeof (uint64_t) * 8));
+
+  if (c == (sizeof (uint64_t) * 8))
+    {
+      assert (s == 0);
+      return w;
+    }
+  else
+    return (w >> s) & ((1ULL << c) - 1);
+}
+
+/* Return the C bits of word W ending at bit E.  (The LSB is 0 and the
+   MSB is (sizeof (unsigned int) * 8).)  */
+static inline unsigned int
+extract_bits_inv (unsigned int w, int e, int c)
+{
+  /* We special case this check here to allow extract_bits_inv (w, 31,
+     0).  */
+  if (c == 0)
+    return 0;
+
+  return extract_bits (w, e - c + 1, c);
+}
+
+static inline uint64_t
+extract_bits64_inv (uint64_t w, int e, int c)
+{
+  /* We special case this check here to allow extract_bits64_inv (w, 63,
+     0).  */
+  if (c == 0)
+    return 0;
+
+  return extract_bits64 (w, e - c + 1, c);
+}
+
+#endif