utcb handling helper routines for the thread library.

This is one of the steps we need in the process of providing a similar interface
for thread creation which can be found in the mainstream operating systems like
Linux.

conts/libl4thread/include/l4thread/bit.h

@@ -0,0 +1,42 @@
+#ifndef __BIT_H__
+#define __BIT_H__
+
+unsigned int __clz(unsigned int bitvector);
+int find_and_set_first_free_bit(u32 *word, unsigned int lastbit);
+int find_and_set_first_free_contig_bits(u32 *word,  unsigned int limit,
+					int nbits);
+int check_and_clear_bit(u32 *word, int bit);
+int check_and_clear_contig_bits(u32 *word, int first, int nbits);
+
+int check_and_set_bit(u32 *word, int bit);
+
+/* Set */
+static inline void setbit(unsigned int *w, unsigned int flags)
+{
+	*w |= flags;
+}
+
+
+/* Clear */
+static inline void clrbit(unsigned int *w, unsigned int flags)
+{
+	*w &= ~flags;
+}
+
+/* Test */
+static inline int tstbit(unsigned int *w, unsigned int flags)
+{
+	return *w & flags;
+}
+
+/* Test and clear */
+static inline int tstclr(unsigned int *w, unsigned int flags)
+{
+	int res = tstbit(w, flags);
+
+	clrbit(w, flags);
+
+	return res;
+}
+
+#endif /* __BIT_H__ */