splitlog2.h

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/*
 * (c) 2008-2009 Adam Lackorzynski <adam@os.inf.tu-dresden.de>
 *     economic rights: Technische Universität Dresden (Germany)
 * License: see LICENSE.spdx (in this directory or the directories above)
 */
#ifndef __L4UTIL__INCLUDE__SPLITLOG2_H__
#define __L4UTIL__INCLUDE__SPLITLOG2_H__
 
#include <l4/sys/linkage.h>
#include <l4/sys/err.h>
#include <l4/util/bitops.h>
 
L4_BEGIN_DECLS

L4_INLINE long
l4util_splitlog2_hdl(l4_addr_t start, l4_addr_t end,
                     long (*handler)(l4_addr_t s, l4_addr_t e, int log2size));

L4_INLINE l4_addr_t
l4util_splitlog2_size(l4_addr_t start, l4_addr_t end);
 
L4_END_DECLS
 
/* Implementation */
 
L4_INLINE long
l4util_splitlog2_hdl(l4_addr_t start, l4_addr_t end,
                     long (*handler)(l4_addr_t s, l4_addr_t e, int log2size))
{
  if (end < start)
    return -L4_EINVAL;
 
  for (;;)
    {
      long retval;
      int len2 = l4util_splitlog2_size(start, end);
      l4_addr_t len = 1UL << len2;
      l4_addr_t chunk_end = start + len - 1;
      if ((retval = handler(start, chunk_end, len2)))
        return retval;
      if (chunk_end >= end)
        return 0;
      start = chunk_end + 1;
    }
}
 
L4_INLINE l4_addr_t
l4util_splitlog2_size(l4_addr_t start, l4_addr_t end)
{
  int start_bits = l4util_bsf(start);
  l4_addr_t len = end - start + 1; // == 0 for entire address space
  int len_bits = len ? l4util_bsr(len) : (int)(sizeof(l4_addr_t) * 8 - 1);
  if (start_bits != -1 && len_bits > start_bits)
    len_bits = start_bits;
 
  return len_bits;
}
 
#endif /* ! __L4UTIL__INCLUDE__SPLITLOG2_H__ */