Subversion Repositories or1k

/* $Id: bitops.h,v 1.1 2005-12-20 11:32:11 jcastillo Exp $

 * bitops.h: Bit string operations on the Sparc.

 *

 * Copyright 1995, David S. Miller (davem@caip.rutgers.edu).

 */

#ifndef _SPARC_BITOPS_H

#define _SPARC_BITOPS_H

#include <linux/kernel.h>

#ifdef __KERNEL__

#include <asm/system.h>

#endif

#ifdef __SMP__

#define SMPVOL volatile

#else

#define SMPVOL

#endif

/* Set bit 'nr' in 32-bit quantity at address 'addr' where bit '0'

 * is in the highest of the four bytes and bit '31' is the high bit

 * within the first byte. Sparc is BIG-Endian. Unless noted otherwise

 * all bit-ops return 0 if bit was previously clear and != 0 otherwise.

 */

extern __inline__ unsigned long set_bit(unsigned long nr, SMPVOL void *addr)

{

        int mask, flags;

        unsigned long *ADDR = (unsigned long *) addr;

        unsigned long oldbit;

        ADDR += nr >> 5;

        mask = 1 << (nr & 31);

        save_flags(flags); cli();

        oldbit = (mask & *ADDR);

        *ADDR |= mask;

        restore_flags(flags);

        return oldbit != 0;

}

extern __inline__ unsigned long clear_bit(unsigned long nr, SMPVOL void *addr)

{

        int mask, flags;

        unsigned long *ADDR = (unsigned long *) addr;

        unsigned long oldbit;

        ADDR += nr >> 5;

        mask = 1 << (nr & 31);

        save_flags(flags); cli();

        oldbit = (mask & *ADDR);

        *ADDR &= ~mask;

        restore_flags(flags);

        return oldbit != 0;

}

extern __inline__ unsigned long change_bit(unsigned long nr, SMPVOL void *addr)

{

        int mask, flags;

        unsigned long *ADDR = (unsigned long *) addr;

        unsigned long oldbit;

        ADDR += nr >> 5;

        mask = 1 << (nr & 31);

        save_flags(flags); cli();

        oldbit = (mask & *ADDR);

        *ADDR ^= mask;

        restore_flags(flags);

        return oldbit != 0;

}

/* The following routine need not be atomic. */

extern __inline__ unsigned long test_bit(int nr, const SMPVOL void *addr)

{

        return ((1UL << (nr & 31)) & (((const unsigned int *) addr)[nr >> 5])) != 0;

}

/* The easy/cheese version for now. */

extern __inline__ unsigned long ffz(unsigned long word)

{

        unsigned long result = 0;

        while(word & 1) {

                result++;

                word >>= 1;

        }

        return result;

}

/* find_next_zero_bit() finds the first zero bit in a bit string of length

 * 'size' bits, starting the search at bit 'offset'. This is largely based

 * on Linus's ALPHA routines, which are pretty portable BTW.

 */

extern __inline__ unsigned long find_next_zero_bit(void *addr, unsigned long size, unsigned long offset)

{

        unsigned long *p = ((unsigned long *) addr) + (offset >> 5);

        unsigned long result = offset & ~31UL;

        unsigned long tmp;

        if (offset >= size)

                return size;

        size -= result;

        offset &= 31UL;

        if (offset) {

                tmp = *(p++);

                tmp |= ~0UL >> (32-offset);

                if (size < 32)

                        goto found_first;

                if (~tmp)

                        goto found_middle;

                size -= 32;

                result += 32;

        }

        while (size & ~31UL) {

                if (~(tmp = *(p++)))

                        goto found_middle;

                result += 32;

                size -= 32;

        }

        if (!size)

                return result;

        tmp = *p;

found_first:

        tmp |= ~0UL >> size;

found_middle:

        return result + ffz(tmp);

}

/* Linus sez that gcc can optimize the following correctly, we'll see if this

 * holds on the Sparc as it does for the ALPHA.

 */

#define find_first_zero_bit(addr, size) \

        find_next_zero_bit((addr), (size), 0)

/* Now for the ext2 filesystem bit operations and helper routines. */

extern __inline__ int ext2_set_bit(int nr,void * addr)

{

        int             mask, retval, flags;

        unsigned char   *ADDR = (unsigned char *) addr;

        ADDR += nr >> 3;

        mask = 1 << (nr & 0x07);

        save_flags(flags); cli();

        retval = (mask & *ADDR) != 0;

        *ADDR |= mask;

        restore_flags(flags);

        return retval;

}

extern __inline__ int ext2_clear_bit(int nr, void * addr)

{

        int             mask, retval, flags;

        unsigned char   *ADDR = (unsigned char *) addr;

        ADDR += nr >> 3;

        mask = 1 << (nr & 0x07);

        save_flags(flags); cli();

        retval = (mask & *ADDR) != 0;

        *ADDR &= ~mask;

        restore_flags(flags);

        return retval;

}

extern __inline__ int ext2_test_bit(int nr, const void * addr)

{

        int                     mask;

        const unsigned char     *ADDR = (const unsigned char *) addr;

        ADDR += nr >> 3;

        mask = 1 << (nr & 0x07);

        return ((mask & *ADDR) != 0);

}

#define ext2_find_first_zero_bit(addr, size) \

        ext2_find_next_zero_bit((addr), (size), 0)

extern __inline__ unsigned long ext2_find_next_zero_bit(void *addr, unsigned long size, unsigned long offset)

{

        unsigned long *p = ((unsigned long *) addr) + (offset >> 5);

        unsigned long result = offset & ~31UL;

        unsigned long tmp;

        if (offset >= size)

                return size;

        size -= result;

        offset &= 31UL;

        if(offset) {

                tmp = *(p++);

                tmp |= ~0UL << (32-offset);

                if(size < 32)

                        goto found_first;

                if(~tmp)

                        goto found_middle;

                size -= 32;

                result += 32;

        }

        while(size & ~31UL) {

                if(~(tmp = *(p++)))

                        goto found_middle;

                result += 32;

                size -= 32;

        }

        if(!size)

                return result;

        tmp = *p;

found_first:

        tmp |= ~0UL << size;

found_middle:

        tmp = ((tmp>>24) | ((tmp>>8)&0xff00) | ((tmp<<8)&0xff0000) | (tmp<<24));

        return result + ffz(tmp);

}

#endif /* defined(_SPARC_BITOPS_H) */