arch/arm/include/asm/bitops.h - arm/linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright 1995, Russell King.
  * Various bits and pieces copyrights include:
  *  Linus Torvalds (test_bit).
  * Big endian support: Copyright 2001, Nicolas Pitre
  *  reworked by rmk.
  *
  * bit 0 is the LSB of an "unsigned long" quantity.
  *
  * Please note that the code in this file should never be included
  * from user space.  Many of these are not implemented in assembler
  * since they would be too costly.  Also, they require privileged
  * instructions (which are not available from user mode) to ensure
  * that they are atomic.
  */

 #ifndef __ASM_ARM_BITOPS_H
 #define __ASM_ARM_BITOPS_H

 #ifdef __KERNEL__

 #ifndef _LINUX_BITOPS_H
 #error only <linux/bitops.h> can be included directly
 #endif

 #include <linux/compiler.h>
 #include <linux/irqflags.h>
 #include <asm/barrier.h>

 /*
  * These functions are the basis of our bit ops.
  *
  * First, the atomic bitops. These use native endian.
  */
 static inline void ____atomic_set_bit(unsigned int bit, volatile unsigned long *p)
 {
 	unsigned long flags;
 	unsigned long mask = BIT_MASK(bit);

 	p += BIT_WORD(bit);

 	raw_local_irq_save(flags);
 	*p |= mask;
 	raw_local_irq_restore(flags);
 }

 static inline void ____atomic_clear_bit(unsigned int bit, volatile unsigned long *p)
 {
 	unsigned long flags;
 	unsigned long mask = BIT_MASK(bit);

 	p += BIT_WORD(bit);

 	raw_local_irq_save(flags);
 	*p &= ~mask;
 	raw_local_irq_restore(flags);
 }

 static inline void ____atomic_change_bit(unsigned int bit, volatile unsigned long *p)
 {
 	unsigned long flags;
 	unsigned long mask = BIT_MASK(bit);

 	p += BIT_WORD(bit);

 	raw_local_irq_save(flags);
 	*p ^= mask;
 	raw_local_irq_restore(flags);
 }

 static inline int
 ____atomic_test_and_set_bit(unsigned int bit, volatile unsigned long *p)
 {
 	unsigned long flags;
 	unsigned int res;
 	unsigned long mask = BIT_MASK(bit);

 	p += BIT_WORD(bit);

 	raw_local_irq_save(flags);
 	res = *p;
 	*p = res | mask;
 	raw_local_irq_restore(flags);

 	return (res & mask) != 0;
 }

 static inline int
 ____atomic_test_and_clear_bit(unsigned int bit, volatile unsigned long *p)
 {
 	unsigned long flags;
 	unsigned int res;
 	unsigned long mask = BIT_MASK(bit);

 	p += BIT_WORD(bit);

 	raw_local_irq_save(flags);
 	res = *p;
 	*p = res & ~mask;
 	raw_local_irq_restore(flags);

 	return (res & mask) != 0;
 }

 static inline int
 ____atomic_test_and_change_bit(unsigned int bit, volatile unsigned long *p)
 {
 	unsigned long flags;
 	unsigned int res;
 	unsigned long mask = BIT_MASK(bit);

 	p += BIT_WORD(bit);

 	raw_local_irq_save(flags);
 	res = *p;
 	*p = res ^ mask;
 	raw_local_irq_restore(flags);

 	return (res & mask) != 0;
 }

 #include <asm-generic/bitops/non-atomic.h>

 /*
  *  A note about Endian-ness.
  *  -------------------------
  *
  * When the ARM is put into big endian mode via CR15, the processor
  * merely swaps the order of bytes within words, thus:
  *
  *          ------------ physical data bus bits -----------
  *          D31 ... D24  D23 ... D16  D15 ... D8  D7 ... D0
  * little     byte 3       byte 2       byte 1      byte 0
  * big        byte 0       byte 1       byte 2      byte 3
  *
  * This means that reading a 32-bit word at address 0 returns the same
  * value irrespective of the endian mode bit.
  *
  * Peripheral devices should be connected with the data bus reversed in
  * "Big Endian" mode.  ARM Application Note 61 is applicable, and is
  * available from http://www.arm.com/.
  *
  * The following assumes that the data bus connectivity for big endian
  * mode has been followed.
  *
  * Note that bit 0 is defined to be 32-bit word bit 0, not byte 0 bit 0.
  */

 /*
  * Native endian assembly bitops.  nr = 0 -> word 0 bit 0.
  */
 extern void _set_bit(int nr, volatile unsigned long * p);
 extern void _clear_bit(int nr, volatile unsigned long * p);
 extern void _change_bit(int nr, volatile unsigned long * p);
 extern int _test_and_set_bit(int nr, volatile unsigned long * p);
 extern int _test_and_clear_bit(int nr, volatile unsigned long * p);
 extern int _test_and_change_bit(int nr, volatile unsigned long * p);

 /*
  * Little endian assembly bitops.  nr = 0 -> byte 0 bit 0.
  */
 extern int _find_first_zero_bit_le(const unsigned long *p, unsigned size);
 extern int _find_next_zero_bit_le(const unsigned long *p, int size, int offset);
 extern int _find_first_bit_le(const unsigned long *p, unsigned size);
 extern int _find_next_bit_le(const unsigned long *p, int size, int offset);

 /*
  * Big endian assembly bitops.  nr = 0 -> byte 3 bit 0.
  */
 extern int _find_first_zero_bit_be(const unsigned long *p, unsigned size);
 extern int _find_next_zero_bit_be(const unsigned long *p, int size, int offset);
 extern int _find_first_bit_be(const unsigned long *p, unsigned size);
 extern int _find_next_bit_be(const unsigned long *p, int size, int offset);

 #ifndef CONFIG_SMP
 /*
  * The __* form of bitops are non-atomic and may be reordered.
  */
 #define ATOMIC_BITOP(name,nr,p)			\
 	(__builtin_constant_p(nr) ? ____atomic_##name(nr, p) : _##name(nr,p))
 #else
 #define ATOMIC_BITOP(name,nr,p)		_##name(nr,p)
 #endif

 /*
  * Native endian atomic definitions.
  */
 #define set_bit(nr,p)			ATOMIC_BITOP(set_bit,nr,p)
 #define clear_bit(nr,p)			ATOMIC_BITOP(clear_bit,nr,p)
 #define change_bit(nr,p)		ATOMIC_BITOP(change_bit,nr,p)
 #define test_and_set_bit(nr,p)		ATOMIC_BITOP(test_and_set_bit,nr,p)
 #define test_and_clear_bit(nr,p)	ATOMIC_BITOP(test_and_clear_bit,nr,p)
 #define test_and_change_bit(nr,p)	ATOMIC_BITOP(test_and_change_bit,nr,p)

 #ifndef __ARMEB__
 /*
  * These are the little endian, atomic definitions.
  */
 #define find_first_zero_bit(p,sz)	_find_first_zero_bit_le(p,sz)
 #define find_next_zero_bit(p,sz,off)	_find_next_zero_bit_le(p,sz,off)
 #define find_first_bit(p,sz)		_find_first_bit_le(p,sz)
 #define find_next_bit(p,sz,off)		_find_next_bit_le(p,sz,off)

 #else
 /*
  * These are the big endian, atomic definitions.
  */
 #define find_first_zero_bit(p,sz)	_find_first_zero_bit_be(p,sz)
 #define find_next_zero_bit(p,sz,off)	_find_next_zero_bit_be(p,sz,off)
 #define find_first_bit(p,sz)		_find_first_bit_be(p,sz)
 #define find_next_bit(p,sz,off)		_find_next_bit_be(p,sz,off)

 #endif

 #if __LINUX_ARM_ARCH__ < 5

 #include <asm-generic/bitops/ffz.h>
 #include <asm-generic/bitops/__fls.h>
 #include <asm-generic/bitops/__ffs.h>
 #include <asm-generic/bitops/fls.h>
 #include <asm-generic/bitops/ffs.h>

 #else

 static inline int constant_fls(int x)
 {
 	int r = 32;

 	if (!x)
 		return 0;
 	if (!(x & 0xffff0000u)) {
 		x <<= 16;
 		r -= 16;
 	}
 	if (!(x & 0xff000000u)) {
 		x <<= 8;
 		r -= 8;
 	}
 	if (!(x & 0xf0000000u)) {
 		x <<= 4;
 		r -= 4;
 	}
 	if (!(x & 0xc0000000u)) {
 		x <<= 2;
 		r -= 2;
 	}
 	if (!(x & 0x80000000u)) {
 		x <<= 1;
 		r -= 1;
 	}
 	return r;
 }

 /*
  * On ARMv5 and above those functions can be implemented around the
  * clz instruction for much better code efficiency.  __clz returns
  * the number of leading zeros, zero input will return 32, and
  * 0x80000000 will return 0.
  */
 static inline unsigned int __clz(unsigned int x)
 {
 	unsigned int ret;

 	asm("clz\t%0, %1" : "=r" (ret) : "r" (x));

 	return ret;
 }

 /*
  * fls() returns zero if the input is zero, otherwise returns the bit
  * position of the last set bit, where the LSB is 1 and MSB is 32.
  */
 static inline int fls(int x)
 {
 	if (__builtin_constant_p(x))
 	       return constant_fls(x);

 	return 32 - __clz(x);
 }

 /*
  * __fls() returns the bit position of the last bit set, where the
  * LSB is 0 and MSB is 31.  Zero input is undefined.
  */
 static inline unsigned long __fls(unsigned long x)
 {
 	return fls(x) - 1;
 }

 /*
  * ffs() returns zero if the input was zero, otherwise returns the bit
  * position of the first set bit, where the LSB is 1 and MSB is 32.
  */
 static inline int ffs(int x)
 {
 	return fls(x & -x);
 }

 /*
  * __ffs() returns the bit position of the first bit set, where the
  * LSB is 0 and MSB is 31.  Zero input is undefined.
  */
 static inline unsigned long __ffs(unsigned long x)
 {
 	return ffs(x) - 1;
 }

 #define ffz(x) __ffs( ~(x) )

 #endif

 #include <asm-generic/bitops/fls64.h>

 #include <asm-generic/bitops/sched.h>
 #include <asm-generic/bitops/hweight.h>
 #include <asm-generic/bitops/lock.h>

 #ifdef __ARMEB__

 static inline int find_first_zero_bit_le(const void *p, unsigned size)
 {
 	return _find_first_zero_bit_le(p, size);
 }
 #define find_first_zero_bit_le find_first_zero_bit_le

 static inline int find_next_zero_bit_le(const void *p, int size, int offset)
 {
 	return _find_next_zero_bit_le(p, size, offset);
 }
 #define find_next_zero_bit_le find_next_zero_bit_le

 static inline int find_next_bit_le(const void *p, int size, int offset)
 {
 	return _find_next_bit_le(p, size, offset);
 }
 #define find_next_bit_le find_next_bit_le

 #endif

 #include <asm-generic/bitops/le.h>

 /*
  * Ext2 is defined to use little-endian byte ordering.
  */
 #include <asm-generic/bitops/ext2-atomic-setbit.h>

 #endif /* __KERNEL__ */

 #endif /* _ARM_BITOPS_H */
	/* SPDX-License-Identifier: GPL-2.0 */
	/*
	* Copyright 1995, Russell King.
	* Various bits and pieces copyrights include:
	* Linus Torvalds (test_bit).
	* Big endian support: Copyright 2001, Nicolas Pitre
	* reworked by rmk.
	*
	* bit 0 is the LSB of an "unsigned long" quantity.
	*
	* Please note that the code in this file should never be included
	* from user space. Many of these are not implemented in assembler
	* since they would be too costly. Also, they require privileged
	* instructions (which are not available from user mode) to ensure
	* that they are atomic.
	*/

	#ifndef __ASM_ARM_BITOPS_H
	#define __ASM_ARM_BITOPS_H

	#ifdef __KERNEL__

	#ifndef _LINUX_BITOPS_H
	#error only <linux/bitops.h> can be included directly
	#endif

	#include <linux/compiler.h>
	#include <linux/irqflags.h>
	#include <asm/barrier.h>

	/*
	* These functions are the basis of our bit ops.
	*
	* First, the atomic bitops. These use native endian.
	*/
	static inline void ____atomic_set_bit(unsigned int bit, volatile unsigned long *p)
	{
	unsigned long flags;
	unsigned long mask = BIT_MASK(bit);

	p += BIT_WORD(bit);

	raw_local_irq_save(flags);
	*p \|= mask;
	raw_local_irq_restore(flags);
	}

	static inline void ____atomic_clear_bit(unsigned int bit, volatile unsigned long *p)
	{
	unsigned long flags;
	unsigned long mask = BIT_MASK(bit);

	p += BIT_WORD(bit);

	raw_local_irq_save(flags);
	*p &= ~mask;
	raw_local_irq_restore(flags);
	}

	static inline void ____atomic_change_bit(unsigned int bit, volatile unsigned long *p)
	{
	unsigned long flags;
	unsigned long mask = BIT_MASK(bit);

	p += BIT_WORD(bit);

	raw_local_irq_save(flags);
	*p ^= mask;
	raw_local_irq_restore(flags);
	}

	static inline int
	____atomic_test_and_set_bit(unsigned int bit, volatile unsigned long *p)
	{
	unsigned long flags;
	unsigned int res;
	unsigned long mask = BIT_MASK(bit);

	p += BIT_WORD(bit);

	raw_local_irq_save(flags);
	res = *p;
	*p = res \| mask;
	raw_local_irq_restore(flags);

	return (res & mask) != 0;
	}

	static inline int
	____atomic_test_and_clear_bit(unsigned int bit, volatile unsigned long *p)
	{
	unsigned long flags;
	unsigned int res;
	unsigned long mask = BIT_MASK(bit);

	p += BIT_WORD(bit);

	raw_local_irq_save(flags);
	res = *p;
	*p = res & ~mask;
	raw_local_irq_restore(flags);

	return (res & mask) != 0;
	}

	static inline int
	____atomic_test_and_change_bit(unsigned int bit, volatile unsigned long *p)
	{
	unsigned long flags;
	unsigned int res;
	unsigned long mask = BIT_MASK(bit);

	p += BIT_WORD(bit);

	raw_local_irq_save(flags);
	res = *p;
	*p = res ^ mask;
	raw_local_irq_restore(flags);

	return (res & mask) != 0;
	}

	#include <asm-generic/bitops/non-atomic.h>

	/*
	* A note about Endian-ness.
	* -------------------------
	*
	* When the ARM is put into big endian mode via CR15, the processor
	* merely swaps the order of bytes within words, thus:
	*
	* ------------ physical data bus bits -----------
	* D31 ... D24 D23 ... D16 D15 ... D8 D7 ... D0
	* little byte 3 byte 2 byte 1 byte 0
	* big byte 0 byte 1 byte 2 byte 3
	*
	* This means that reading a 32-bit word at address 0 returns the same
	* value irrespective of the endian mode bit.
	*
	* Peripheral devices should be connected with the data bus reversed in
	* "Big Endian" mode. ARM Application Note 61 is applicable, and is
	* available from http://www.arm.com/.
	*
	* The following assumes that the data bus connectivity for big endian
	* mode has been followed.
	*
	* Note that bit 0 is defined to be 32-bit word bit 0, not byte 0 bit 0.
	*/

	/*
	* Native endian assembly bitops. nr = 0 -> word 0 bit 0.
	*/
	extern void _set_bit(int nr, volatile unsigned long * p);
	extern void _clear_bit(int nr, volatile unsigned long * p);
	extern void _change_bit(int nr, volatile unsigned long * p);
	extern int _test_and_set_bit(int nr, volatile unsigned long * p);
	extern int _test_and_clear_bit(int nr, volatile unsigned long * p);
	extern int _test_and_change_bit(int nr, volatile unsigned long * p);

	/*
	* Little endian assembly bitops. nr = 0 -> byte 0 bit 0.
	*/
	extern int _find_first_zero_bit_le(const unsigned long *p, unsigned size);
	extern int _find_next_zero_bit_le(const unsigned long *p, int size, int offset);
	extern int _find_first_bit_le(const unsigned long *p, unsigned size);
	extern int _find_next_bit_le(const unsigned long *p, int size, int offset);

	/*
	* Big endian assembly bitops. nr = 0 -> byte 3 bit 0.
	*/
	extern int _find_first_zero_bit_be(const unsigned long *p, unsigned size);
	extern int _find_next_zero_bit_be(const unsigned long *p, int size, int offset);
	extern int _find_first_bit_be(const unsigned long *p, unsigned size);
	extern int _find_next_bit_be(const unsigned long *p, int size, int offset);

	#ifndef CONFIG_SMP
	/*
	* The __* form of bitops are non-atomic and may be reordered.
	*/
	#define ATOMIC_BITOP(name,nr,p) \
	(__builtin_constant_p(nr) ? ____atomic_##name(nr, p) : _##name(nr,p))
	#else
	#define ATOMIC_BITOP(name,nr,p) _##name(nr,p)
	#endif

	/*
	* Native endian atomic definitions.
	*/
	#define set_bit(nr,p) ATOMIC_BITOP(set_bit,nr,p)
	#define clear_bit(nr,p) ATOMIC_BITOP(clear_bit,nr,p)
	#define change_bit(nr,p) ATOMIC_BITOP(change_bit,nr,p)
	#define test_and_set_bit(nr,p) ATOMIC_BITOP(test_and_set_bit,nr,p)
	#define test_and_clear_bit(nr,p) ATOMIC_BITOP(test_and_clear_bit,nr,p)
	#define test_and_change_bit(nr,p) ATOMIC_BITOP(test_and_change_bit,nr,p)

	#ifndef __ARMEB__
	/*
	* These are the little endian, atomic definitions.
	*/
	#define find_first_zero_bit(p,sz) _find_first_zero_bit_le(p,sz)
	#define find_next_zero_bit(p,sz,off) _find_next_zero_bit_le(p,sz,off)
	#define find_first_bit(p,sz) _find_first_bit_le(p,sz)
	#define find_next_bit(p,sz,off) _find_next_bit_le(p,sz,off)

	#else
	/*
	* These are the big endian, atomic definitions.
	*/
	#define find_first_zero_bit(p,sz) _find_first_zero_bit_be(p,sz)
	#define find_next_zero_bit(p,sz,off) _find_next_zero_bit_be(p,sz,off)
	#define find_first_bit(p,sz) _find_first_bit_be(p,sz)
	#define find_next_bit(p,sz,off) _find_next_bit_be(p,sz,off)

	#endif

	#if __LINUX_ARM_ARCH__ < 5

	#include <asm-generic/bitops/ffz.h>
	#include <asm-generic/bitops/__fls.h>
	#include <asm-generic/bitops/__ffs.h>
	#include <asm-generic/bitops/fls.h>
	#include <asm-generic/bitops/ffs.h>

	#else

	static inline int constant_fls(int x)
	{
	int r = 32;

	if (!x)
	return 0;
	if (!(x & 0xffff0000u)) {
	x <<= 16;
	r -= 16;
	}
	if (!(x & 0xff000000u)) {
	x <<= 8;
	r -= 8;
	}
	if (!(x & 0xf0000000u)) {
	x <<= 4;
	r -= 4;
	}
	if (!(x & 0xc0000000u)) {
	x <<= 2;
	r -= 2;
	}
	if (!(x & 0x80000000u)) {
	x <<= 1;
	r -= 1;
	}
	return r;
	}

	/*
	* On ARMv5 and above those functions can be implemented around the
	* clz instruction for much better code efficiency. __clz returns
	* the number of leading zeros, zero input will return 32, and
	* 0x80000000 will return 0.
	*/
	static inline unsigned int __clz(unsigned int x)
	{
	unsigned int ret;

	asm("clz\t%0, %1" : "=r" (ret) : "r" (x));

	return ret;
	}

	/*
	* fls() returns zero if the input is zero, otherwise returns the bit
	* position of the last set bit, where the LSB is 1 and MSB is 32.
	*/
	static inline int fls(int x)
	{
	if (__builtin_constant_p(x))
	return constant_fls(x);

	return 32 - __clz(x);
	}

	/*
	* __fls() returns the bit position of the last bit set, where the
	* LSB is 0 and MSB is 31. Zero input is undefined.
	*/
	static inline unsigned long __fls(unsigned long x)
	{
	return fls(x) - 1;
	}

	/*
	* ffs() returns zero if the input was zero, otherwise returns the bit
	* position of the first set bit, where the LSB is 1 and MSB is 32.
	*/
	static inline int ffs(int x)
	{
	return fls(x & -x);
	}

	/*
	* __ffs() returns the bit position of the first bit set, where the
	* LSB is 0 and MSB is 31. Zero input is undefined.
	*/
	static inline unsigned long __ffs(unsigned long x)
	{
	return ffs(x) - 1;
	}

	#define ffz(x) __ffs( ~(x) )

	#endif

	#include <asm-generic/bitops/fls64.h>

	#include <asm-generic/bitops/sched.h>
	#include <asm-generic/bitops/hweight.h>
	#include <asm-generic/bitops/lock.h>

	#ifdef __ARMEB__

	static inline int find_first_zero_bit_le(const void *p, unsigned size)
	{
	return _find_first_zero_bit_le(p, size);
	}
	#define find_first_zero_bit_le find_first_zero_bit_le

	static inline int find_next_zero_bit_le(const void *p, int size, int offset)
	{
	return _find_next_zero_bit_le(p, size, offset);
	}
	#define find_next_zero_bit_le find_next_zero_bit_le

	static inline int find_next_bit_le(const void *p, int size, int offset)
	{
	return _find_next_bit_le(p, size, offset);
	}
	#define find_next_bit_le find_next_bit_le

	#endif

	#include <asm-generic/bitops/le.h>

	/*
	* Ext2 is defined to use little-endian byte ordering.
	*/
	#include <asm-generic/bitops/ext2-atomic-setbit.h>

	#endif /* __KERNEL__ */

	#endif /* _ARM_BITOPS_H */