portability and compression cleanups

[wimlib] / include / wimlib / bitops.h

diff --git a/include/wimlib/bitops.h b/include/wimlib/bitops.h
new file mode 100644 (file)
index 0000000..2e7a948
--- /dev/null
+++ b/include/wimlib/bitops.h
@@ -0,0 +1,92 @@
+/*
+ * bitops.h
+ *
+ * Inline functions for bit manipulation.
+ *
+ * The author dedicates this file to the public domain.
+ * You can do whatever you want with this file.
+ */
+
+#ifndef _WIMLIB_BITOPS_H
+#define _WIMLIB_BITOPS_H
+
+#include "wimlib/compiler.h"
+#include "wimlib/types.h"
+
+/* Find Last Set bit   */
+
+static inline unsigned
+fls32(u32 v)
+{
+#ifdef compiler_fls32
+       return compiler_fls32(v);
+#else
+       unsigned bit = 0;
+       while ((v >>= 1) != 0)
+               bit++;
+       return bit;
+#endif
+}
+
+static inline unsigned
+fls64(u64 v)
+{
+#ifdef compiler_fls64
+       return compiler_fls64(v);
+#else
+       unsigned bit = 0;
+       while ((v >>= 1) != 0)
+               bit++;
+       return bit;
+#endif
+}
+
+static inline unsigned
+flsw(machine_word_t v)
+{
+       BUILD_BUG_ON(WORDSIZE != 4 && WORDSIZE != 8);
+       if (WORDSIZE == 4)
+               return fls32(v);
+       else
+               return fls64(v);
+}
+
+/* Find First Set bit   */
+
+static inline unsigned
+ffs32(u32 v)
+{
+#ifdef compiler_ffs32
+       return compiler_ffs32(v);
+#else
+       unsigned bit;
+       for (bit = 0; !(v & 1); bit++, v >>= 1)
+               ;
+       return bit;
+#endif
+}
+
+static inline unsigned
+ffs64(u64 v)
+{
+#ifdef compiler_ffs64
+       return compiler_ffs64(v);
+#else
+       unsigned bit;
+       for (bit = 0; !(v & 1); bit++, v >>= 1)
+               ;
+       return bit;
+#endif
+}
+
+static inline unsigned
+ffsw(machine_word_t v)
+{
+       BUILD_BUG_ON(WORDSIZE != 4 && WORDSIZE != 8);
+       if (WORDSIZE == 4)
+               return ffs32(v);
+       else
+               return ffs64(v);
+}
+
+#endif /* _WIMLIB_BITOPS_H */