Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * bitext.c: kernel little helper (of bit shuffling variety).

 *

 * Copyright (C) 2002 Pete Zaitcev <zaitcev@yahoo.com>

 *

 * The algorithm to search a zero bit string is geared towards its application.

 * We expect a couple of fixed sizes of requests, so a rotating counter, reset

 * by align size, should provide fast enough search while maintaining low

 * fragmentation.

 */

#include <linux/string.h>

#include <linux/bitops.h>

#include <asm/bitext.h>

/**

 * bit_map_string_get - find and set a bit string in bit map.

 * @t: the bit map.

 * @len: requested string length

 * @align: requested alignment

 *

 * Returns offset in the map or -1 if out of space.

 *

 * Not safe to call from an interrupt (uses spin_lock).

 */

int bit_map_string_get(struct bit_map *t, int len, int align)

{

        int offset, count;      /* siamese twins */

        int off_new;

        int align1;

        int i, color;

        if (t->num_colors) {

                /* align is overloaded to be the page color */

                color = align;

                align = t->num_colors;

        } else {

                color = 0;

                if (align == 0)

                        align = 1;

        }

        align1 = align - 1;

        if ((align & align1) != 0)

                BUG();

        if (align < 0 || align >= t->size)

                BUG();

        if (len <= 0 || len > t->size)

                BUG();

        color &= align1;

        spin_lock(&t->lock);

        if (len < t->last_size)

                offset = t->first_free;

        else

                offset = t->last_off & ~align1;

        count = 0;

        for (;;) {

                off_new = find_next_zero_bit(t->map, t->size, offset);

                off_new = ((off_new + align1) & ~align1) + color;

                count += off_new - offset;

                offset = off_new;

                if (offset >= t->size)

                        offset = 0;

                if (count + len > t->size) {

                        spin_unlock(&t->lock);

/* P3 */ printk(KERN_ERR

  "bitmap out: size %d used %d off %d len %d align %d count %d\n",

  t->size, t->used, offset, len, align, count);

                        return -1;

                }

                if (offset + len > t->size) {

                        count += t->size - offset;

                        offset = 0;

                        continue;

                }

                i = 0;

                while (test_bit(offset + i, t->map) == 0) {

                        i++;

                        if (i == len) {

                                for (i = 0; i < len; i++)

                                        __set_bit(offset + i, t->map);

                                if (offset == t->first_free)

                                        t->first_free = find_next_zero_bit

                                                        (t->map, t->size,

                                                         t->first_free + len);

                                if ((t->last_off = offset + len) >= t->size)

                                        t->last_off = 0;

                                t->used += len;

                                t->last_size = len;

                                spin_unlock(&t->lock);

                                return offset;

                        }

                }

                count += i + 1;

                if ((offset += i + 1) >= t->size)

                        offset = 0;

        }

}

void bit_map_clear(struct bit_map *t, int offset, int len)

{

        int i;

        if (t->used < len)

                BUG();          /* Much too late to do any good, but alas... */

        spin_lock(&t->lock);

        for (i = 0; i < len; i++) {

                if (test_bit(offset + i, t->map) == 0)

                        BUG();

                __clear_bit(offset + i, t->map);

        }

        if (offset < t->first_free)

                t->first_free = offset;

        t->used -= len;

        spin_unlock(&t->lock);

}

void bit_map_init(struct bit_map *t, unsigned long *map, int size)

{

        if ((size & 07) != 0)

                BUG();

        memset(map, 0, size>>3);

        memset(t, 0, sizeof *t);

        spin_lock_init(&t->lock);

        t->map = map;

        t->size = size;

}