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/*
* Copyright (c) 2013 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/>.
*
*
* Arbitrary-length bit arrays.
*/
#ifndef _KERN_BITMAP_H
#define _KERN_BITMAP_H
#include <kern/limits.h>
#include <kern/macros.h>
#include <kern/string.h>
#include <machine/atomic.h>
#define BITMAP_LONGS(nr_bits) DIV_CEIL(nr_bits, LONG_BIT)
/*
* Declare a bitmap.
*/
#define BITMAP_DECLARE(name, nr_bits) unsigned long name[BITMAP_LONGS(nr_bits)]
/*
* Helper functions.
*/
static inline void
bitmap_lookup(volatile unsigned long **bm, int *bit)
{
int i;
i = BITMAP_LONGS(*bit + 1) - 1;
*bm += i;
*bit -= i * LONG_BIT;
}
static inline unsigned long
bitmap_mask(int bit)
{
return (1UL << bit);
}
/*
* Public interface.
*/
/*
* Initialize a bitmap, setting all bits to 0.
*/
static inline void
bitmap_init(unsigned long *bm, int nr_bits)
{
int n;
n = BITMAP_LONGS(nr_bits);
memset(bm, 0, n * sizeof(unsigned long));
}
static inline void
bitmap_set(volatile unsigned long *bm, int bit)
{
if (bit >= LONG_BIT)
bitmap_lookup(&bm, &bit);
*bm |= bitmap_mask(bit);
}
static inline void
bitmap_set_atomic(volatile unsigned long *bm, int bit)
{
if (bit >= LONG_BIT)
bitmap_lookup(&bm, &bit);
atomic_or(bm, bitmap_mask(bit));
}
static inline void
bitmap_clear(volatile unsigned long *bm, int bit)
{
if (bit >= LONG_BIT)
bitmap_lookup(&bm, &bit);
*bm &= ~bitmap_mask(bit);
}
static inline void
bitmap_clear_atomic(volatile unsigned long *bm, int bit)
{
if (bit >= LONG_BIT)
bitmap_lookup(&bm, &bit);
atomic_and(bm, ~bitmap_mask(bit));
}
static inline int
bitmap_test(volatile unsigned long *bm, int bit)
{
if (bit >= LONG_BIT)
bitmap_lookup(&bm, &bit);
return ((*bm & bitmap_mask(bit)) != 0);
}
/*
* 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.
*/
static inline int
bitmap_find_next(volatile unsigned long *bm, int nr_bits, int bit)
{
volatile unsigned long *start, *end;
unsigned long word;
start = bm;
end = bm + BITMAP_LONGS(nr_bits);
if (bit >= LONG_BIT)
bitmap_lookup(&bm, &bit);
word = *bm;
if (bit < LONG_BIT)
word &= ~(bitmap_mask(bit) - 1);
for (;;) {
bit = __builtin_ffsl(word);
if (bit != 0)
return ((bm - start) * LONG_BIT) + bit - 1;
bm++;
if (bm >= end)
return -1;
word = *bm;
}
}
static inline int
bitmap_find_first(volatile unsigned long *bm, int nr_bits)
{
return bitmap_find_next(bm, nr_bits, 0);
}
#endif /* _KERN_BITMAP_H */
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