x15/kern/bitmap.h

/*
 * Copyright (c) 2013-2015 Richard Braun.
 *
 * This program 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.
 *
 * This program 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/>.
 *
 * Upstream site with license notes :
 * http://git.sceen.net/rbraun/librbraun.git/
 *
 *
 * Arbitrary-length bit arrays.
 *
 * Most functions do not check whether the given parameters are valid. This
 * is the responsibility of the caller.
 */

#ifndef KERN_BITMAP_H
#define KERN_BITMAP_H

#include <limits.h>
#include <stdbool.h>
#include <string.h>

#include <kern/atomic.h>
#include <kern/macros.h>

#define BITMAP_LONGS(nr_bits)   DIV_CEIL (nr_bits, LONG_BIT)

/*
 * Adjust the bitmap pointer and the bit index so that the latter refers
 * to a bit inside the word pointed by the former.
 *
 * Implemented as a macro for const-correctness.
 */
#define bitmap_lookup(bmp, bitp)   \
MACRO_BEGIN   \
  int i_ = BITMAP_LONGS (*(bitp) + 1) - 1;   \
  *(bmp) += i_;   \
  *(bitp) -= i_ * LONG_BIT;   \
MACRO_END

static inline unsigned long
bitmap_mask (int bit)
{
  return (1UL << bit);
}

/*
 * Return the index of the next set bit in the bitmap, starting (and
 * including) the given bit index, or -1 if the bitmap is empty. If
 * complement is true, bits are toggled before searching so that the
 * result is the index of the next zero bit.
 */
int bitmap_find_next_bit (const unsigned long *bm, int nr_bits, int bit,
                          int complement);

#define BITMAP_DECLARE(name, nr_bits)   \
  unsigned long name[BITMAP_LONGS (nr_bits)]

int bitmap_cmp (const unsigned long *a, const unsigned long *b, int nr_bits);

static inline void
bitmap_zero (unsigned long *bm, int nr_bits)
{
  memset (bm, 0, BITMAP_LONGS (nr_bits) * sizeof (*bm));
}

static inline void
bitmap_fill (unsigned long *bm, int nr_bits)
{
  memset (bm, 0xff, BITMAP_LONGS (nr_bits) * sizeof (*bm));
}

static inline void
bitmap_copy (unsigned long *dest, const unsigned long *src, int nr_bits)
{
  memcpy (dest, src, BITMAP_LONGS (nr_bits) * sizeof (*dest));
}

static inline void
bitmap_set (unsigned long *bm, int bit)
{
  if (bit >= LONG_BIT)
    bitmap_lookup (&bm, &bit);

  *bm |= bitmap_mask (bit);
}

static inline void
bitmap_set_atomic (unsigned long *bm, int bit)
{
  if (bit >= LONG_BIT)
    bitmap_lookup (&bm, &bit);

  atomic_or (bm, bitmap_mask (bit), ATOMIC_RELEASE);
}

static inline void
bitmap_clear (unsigned long *bm, int bit)
{
  if (bit >= LONG_BIT)
    bitmap_lookup (&bm, &bit);

  *bm &= ~bitmap_mask (bit);
}

static inline void
bitmap_clear_atomic (unsigned long *bm, int bit)
{
  if (bit >= LONG_BIT)
    bitmap_lookup (&bm, &bit);

  atomic_and_rel (bm, ~bitmap_mask (bit));
}

static inline bool
bitmap_test (const unsigned long *bm, int bit)
{
  if (bit >= LONG_BIT)
    bitmap_lookup (&bm, &bit);

  return ((*bm & bitmap_mask (bit)) != 0);
}

static inline int
bitmap_test_atomic (const unsigned long *bm, int bit)
{
  if (bit >= LONG_BIT)
    bitmap_lookup (&bm, &bit);

  return ((atomic_load_acq (bm) & bitmap_mask (bit)) != 0);
}

static inline void
bitmap_and (unsigned long *a, const unsigned long *b, int nr_bits)
{
  int n = BITMAP_LONGS (nr_bits);
  for (int i = 0; i < n; i++)
    a[i] &= b[i];
}

static inline void
bitmap_or (unsigned long *a, const unsigned long *b, int nr_bits)
{
  int n = BITMAP_LONGS (nr_bits);
  for (int i = 0; i < n; i++)
    a[i] |= b[i];
}

static inline void
bitmap_xor (unsigned long *a, const unsigned long *b, int nr_bits)
{
  int n = BITMAP_LONGS (nr_bits);
  for (int i = 0; i < n; i++)
    a[i] ^= b[i];
}

static inline int
bitmap_find_next (const unsigned long *bm, int nr_bits, int bit)
{
  return (bitmap_find_next_bit (bm, nr_bits, bit, 0));
}

static inline int
bitmap_find_first (const unsigned long *bm, int nr_bits)
{
  return (bitmap_find_next (bm, nr_bits, 0));
}

static inline int
bitmap_find_next_zero (const unsigned long *bm, int nr_bits, int bit)
{
  return (bitmap_find_next_bit (bm, nr_bits, bit, 1));
}

static inline int
bitmap_find_first_zero (const unsigned long *bm, int nr_bits)
{
  return (bitmap_find_next_zero (bm, nr_bits, 0));
}

static inline bool
bitmap_intersects (const unsigned long *a, const unsigned long *b, int nr_bits)
{
  int n = BITMAP_LONGS (nr_bits);
  for (int i = 0; i < n; i++)
    if (a[i] & b[i])
      return (true);

  return (false);
}

static inline unsigned int
bitmap_count_set (const unsigned long *bm, int nr_bits)
{
  unsigned int ret = 0;
  for (int i = 0; i < BITMAP_LONGS (nr_bits); ++i)
    ret += __builtin_popcountl (bm[i]);

  return (ret);
}

#define bitmap_for_each(bm, nr_bits, bit)   \
  for (int bit = 0;   \
       bit < nr_bits &&   \
         (bit = bitmap_find_next (bm, nr_bits, bit)) != -1;   \
       ++bit)

#define bitmap_for_each_zero(bm, nr_bits, bit)   \
  for (int bit = 0;   \
       bit < nr_bits &&   \
         (bit = bitmap_find_next_zero (bm, nr_bits, bit)) != -1;  \
       ++bit)

#endif