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/*

 * Bit manipulation functions.

 *

 * Copyright (C) 2007 Bahadir Balban

 */

#include <l4/lib/bit.h>

#include INC_GLUE(memory.h)

/* Emulation of ARM's CLZ (count leading zeroes) instruction */

unsigned int __clz(unsigned int bitvector)

{

        unsigned int x = 0;

        while((!(bitvector & ((unsigned)1 << 31))) && (x < 32)) {

                bitvector <<= 1;

                x++;

        }

        return x;

}

int find_and_set_first_free_bit(u32 *word, unsigned int limit)

{

        int success = 0;

        int i;

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

                /* Find first unset bit */

                if (!(word[BITWISE_GETWORD(i)] & BITWISE_GETBIT(i))) {

                        /* Set it */

                        word[BITWISE_GETWORD(i)] |= BITWISE_GETBIT(i);

                        success = 1;

                        break;

                }

        }

        /* Return bit just set */

        if (success)

                return i;

        else

                return -1;

}

int check_and_clear_bit(u32 *word, int bit)

{

        /* Check that bit was set */

        if (word[BITWISE_GETWORD(bit)] & BITWISE_GETBIT(bit)) {

                word[BITWISE_GETWORD(bit)] &= ~BITWISE_GETBIT(bit);

                return 0;

        } else {

                //printf("Trying to clear already clear bit\n");

                return -1;

        }

}

int check_and_set_bit(u32 *word, int bit)

{

        /* Check that bit was clear */

        if (!(word[BITWISE_GETWORD(bit)] & BITWISE_GETBIT(bit))) {

                word[BITWISE_GETWORD(bit)] |= BITWISE_GETBIT(bit);

                return 0;

        } else {

                //printf("Trying to set already set bit\n");

                return -1;

        }

}