atomic.h

ucLinux is a very good embeded sytem. Most of company use this as their development OS.

/* Low-level functions for atomic operations. Mips version.
   Copyright (C) 2005 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef _MIPS_BITS_ATOMIC_H
#define _MIPS_BITS_ATOMIC_H 1

#include <inttypes.h>
#include <sgidefs.h>

typedef int32_t atomic32_t;
typedef uint32_t uatomic32_t;
typedef int_fast32_t atomic_fast32_t;
typedef uint_fast32_t uatomic_fast32_t;

typedef int64_t atomic64_t;
typedef uint64_t uatomic64_t;
typedef int_fast64_t atomic_fast64_t;
typedef uint_fast64_t uatomic_fast64_t;

typedef intptr_t atomicptr_t;
typedef uintptr_t uatomicptr_t;
typedef intmax_t atomic_max_t;
typedef uintmax_t uatomic_max_t;

#if _MIPS_SIM == _ABIO32
#define MIPS_PUSH_MIPS2 ".set	mips2\n\t"
#else
#define MIPS_PUSH_MIPS2
#endif

/* See the comments in <sys/asm.h> about the use of the sync instruction.  */
#ifndef MIPS_SYNC
# define MIPS_SYNC	sync
#endif

#define MIPS_SYNC_STR_2(X) #X
#define MIPS_SYNC_STR_1(X) MIPS_SYNC_STR_2(X)
#define MIPS_SYNC_STR MIPS_SYNC_STR_1(MIPS_SYNC)

/* Compare and exchange.  For all of the "xxx" routines, we expect a
   "__prev" and a "__cmp" variable to be provided by the enclosing scope,
   in which values are returned.  */

#define __arch_compare_and_exchange_xxx_8_int(mem, newval, oldval, rel, acq) \
  (abort (), __prev = __cmp = 0)

#define __arch_compare_and_exchange_xxx_16_int(mem, newval, oldval, rel, acq) \
  (abort (), __prev = __cmp = 0)

#define __arch_compare_and_exchange_xxx_32_int(mem, newval, oldval, rel, acq) \
     __asm__ __volatile__ (						      \
     ".set	push\n\t"						      \
     MIPS_PUSH_MIPS2							      \
     rel	"\n"							      \
     "1:\t"								      \
     "ll	%0,%4\n\t"						      \
     "move	%1,$0\n\t"						      \
     "bne	%0,%2,2f\n\t"						      \
     "move	%1,%3\n\t"						      \
     "sc	%1,%4\n\t"						      \
     "beqz	%1,1b\n"						      \
     acq	"\n\t"							      \
     ".set	pop\n"							      \
     "2:\n\t"								      \
	      : "=&r" (__prev), "=&r" (__cmp)				      \
	      : "r" (oldval), "r" (newval), "m" (*mem)			      \
	      : "memory")

#if _MIPS_SIM == _ABIO32
/* We can't do an atomic 64-bit operation in O32.  */
#define __arch_compare_and_exchange_xxx_64_int(mem, newval, oldval, rel, acq) \
  (abort (), __prev = __cmp = 0)
#else
#define __arch_compare_and_exchange_xxx_64_int(mem, newval, oldval, rel, acq) \
     __asm__ __volatile__ ("\n"						      \
     ".set	push\n\t"						      \
     MIPS_PUSH_MIPS2							      \
     rel	"\n"							      \
     "1:\t"								      \
     "lld	%0,%4\n\t"						      \
     "move	%1,$0\n\t"						      \
     "bne	%0,%2,2f\n\t"						      \
     "move	%1,%3\n\t"						      \
     "scd	%1,%4\n\t"						      \
     "beqz	%1,1b\n"						      \
     acq	"\n\t"							      \
     ".set	pop\n"							      \
     "2:\n\t"								      \
	      : "=&r" (__prev), "=&r" (__cmp)				      \
	      : "r" (oldval), "r" (newval), "m" (*mem)			      \
	      : "memory")
#endif

/* For all "bool" routines, we return FALSE if exchange succesful.  */

#define __arch_compare_and_exchange_bool_8_int(mem, new, old, rel, acq)	\
({ typeof (*mem) __prev; int __cmp;					\
   __arch_compare_and_exchange_xxx_8_int(mem, new, old, rel, acq);	\
   !__cmp; })

#define __arch_compare_and_exchange_bool_16_int(mem, new, old, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					\
   __arch_compare_and_exchange_xxx_16_int(mem, new, old, rel, acq);	\
   !__cmp; })

#define __arch_compare_and_exchange_bool_32_int(mem, new, old, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					\
   __arch_compare_and_exchange_xxx_32_int(mem, new, old, rel, acq);	\
   !__cmp; })

#define __arch_compare_and_exchange_bool_64_int(mem, new, old, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					\
   __arch_compare_and_exchange_xxx_64_int(mem, new, old, rel, acq);	\
   !__cmp; })

/* For all "val" routines, return the old value whether exchange
   successful or not.  */

#define __arch_compare_and_exchange_val_8_int(mem, new, old, rel, acq)	\
({ typeof (*mem) __prev; int __cmp;					\
   __arch_compare_and_exchange_xxx_8_int(mem, new, old, rel, acq);	\
   (typeof (*mem))__prev; })

#define __arch_compare_and_exchange_val_16_int(mem, new, old, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					\
   __arch_compare_and_exchange_xxx_16_int(mem, new, old, rel, acq);	\
   (typeof (*mem))__prev; })

#define __arch_compare_and_exchange_val_32_int(mem, new, old, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					\
   __arch_compare_and_exchange_xxx_32_int(mem, new, old, rel, acq);	\
   (typeof (*mem))__prev; })

#define __arch_compare_and_exchange_val_64_int(mem, new, old, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					\
   __arch_compare_and_exchange_xxx_64_int(mem, new, old, rel, acq);	\
   (typeof (*mem))__prev; })

/* Compare and exchange with "acquire" semantics, ie barrier after.  */

#define atomic_compare_and_exchange_bool_acq(mem, new, old)	\
  __atomic_bool_bysize (__arch_compare_and_exchange_bool, int,	\
		        mem, new, old, "", MIPS_SYNC_STR)

#define atomic_compare_and_exchange_val_acq(mem, new, old)	\
  __atomic_val_bysize (__arch_compare_and_exchange_val, int,	\
		       mem, new, old, "", MIPS_SYNC_STR)

/* Compare and exchange with "release" semantics, ie barrier before.  */

#define atomic_compare_and_exchange_bool_rel(mem, new, old)	\
  __atomic_bool_bysize (__arch_compare_and_exchange_bool, int,	\
		        mem, new, old, MIPS_SYNC_STR, "")

#define atomic_compare_and_exchange_val_rel(mem, new, old)	\
  __atomic_val_bysize (__arch_compare_and_exchange_val, int,	\
		       mem, new, old, MIPS_SYNC_STR, "")



/* Atomic exchange (without compare).  */

#define __arch_exchange_xxx_8_int(mem, newval, rel, acq) \
  (abort (), 0)

#define __arch_exchange_xxx_16_int(mem, newval, rel, acq) \
  (abort (), 0)

#define __arch_exchange_xxx_32_int(mem, newval, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					      \
     __asm__ __volatile__ ("\n"						      \
     ".set	push\n\t"						      \
     MIPS_PUSH_MIPS2							      \
     rel	"\n"							      \
     "1:\t"								      \
     "ll	%0,%3\n\t"						      \
     "move	%1,%2\n\t"						      \
     "sc	%1,%3\n\t"						      \
     "beqz	%1,1b\n"						      \
     acq	"\n\t"							      \
     ".set	pop\n"							      \
     "2:\n\t"								      \
	      : "=&r" (__prev), "=&r" (__cmp)				      \
	      : "r" (newval), "m" (*mem)				      \
	      : "memory");						      \
  __prev; })

#if _MIPS_SIM == _ABIO32
/* We can't do an atomic 64-bit operation in O32.  */
#define __arch_exchange_xxx_64_int(mem, newval, rel, acq) \
  (abort (), 0)
#else
#define __arch_exchange_xxx_64_int(mem, newval, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					      \
     __asm__ __volatile__ ("\n"						      \
     ".set	push\n\t"						      \
     MIPS_PUSH_MIPS2							      \
     rel	"\n"							      \
     "1:\n"								      \
     "lld	%0,%3\n\t"						      \
     "move	%1,%2\n\t"						      \
     "scd	%1,%3\n\t"						      \
     "beqz	%1,1b\n"						      \
     acq	"\n\t"							      \
     ".set	pop\n"							      \
     "2:\n\t"								      \
	      : "=&r" (__prev), "=&r" (__cmp)				      \
	      : "r" (newval), "m" (*mem)				      \
	      : "memory");						      \
  __prev; })
#endif

#define atomic_exchange_acq(mem, value) \
  __atomic_val_bysize (__arch_exchange_xxx, int, mem, value, "", MIPS_SYNC_STR)

#define atomic_exchange_rel(mem, value) \
  __atomic_val_bysize (__arch_exchange_xxx, int, mem, value, MIPS_SYNC_STR, "")


/* Atomically add value and return the previous (unincremented) value.  */

#define __arch_exchange_and_add_8_int(mem, newval, rel, acq) \
  (abort (), (typeof(*mem)) 0)

#define __arch_exchange_and_add_16_int(mem, newval, rel, acq) \
  (abort (), (typeof(*mem)) 0)

#define __arch_exchange_and_add_32_int(mem, value, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					      \
     __asm__ __volatile__ ("\n"						      \
     ".set	push\n\t"						      \
     MIPS_PUSH_MIPS2							      \
     rel	"\n"							      \
     "1:\t"								      \
     "ll	%0,%3\n\t"						      \
     "addu	%1,%0,%2\n\t"						      \
     "sc	%1,%3\n\t"						      \
     "beqz	%1,1b\n"						      \
     acq	"\n\t"							      \
     ".set	pop\n"							      \
     "2:\n\t"								      \
	      : "=&r" (__prev), "=&r" (__cmp)				      \
	      : "r" (value), "m" (*mem)					      \
	      : "memory");						      \
  __prev; })

#if _MIPS_SIM == _ABIO32
/* We can't do an atomic 64-bit operation in O32.  */
#define __arch_exchange_and_add_64_int(mem, value, rel, acq) \
  (abort (), (typeof(*mem)) 0)
#else
#define __arch_exchange_and_add_64_int(mem, value, rel, acq) \
({ typeof (*mem) __prev; int __cmp;					      \
     __asm__ __volatile__ (						      \
     ".set	push\n\t"						      \
     MIPS_PUSH_MIPS2							      \
     rel	"\n"							      \
     "1:\t"								      \
     "lld	%0,%3\n\t"						      \
     "daddu	%1,%0,%2\n\t"						      \
     "scd	%1,%3\n\t"						      \
     "beqz	%1,1b\n"						      \
     acq	"\n\t"							      \
     ".set	pop\n"							      \
     "2:\n\t"								      \
	      : "=&r" (__prev), "=&r" (__cmp)				      \
	      : "r" (value), "m" (*mem)					      \
	      : "memory");						      \
  __prev; })
#endif

/* ??? Barrier semantics for atomic_exchange_and_add appear to be 
   undefined.  Use full barrier for now, as that's safe.  */
#define atomic_exchange_and_add(mem, value) \
  __atomic_val_bysize (__arch_exchange_and_add, int, mem, value,	      \
		       MIPS_SYNC_STR, MIPS_SYNC_STR)

/* TODO: More atomic operations could be implemented efficiently; only the
   basic requirements are done.  */

#define atomic_full_barrier() \
  __asm__ __volatile__ (".set push\n\t"					      \
			MIPS_PUSH_MIPS2					      \
			MIPS_SYNC_STR "\n\t"				      \
			".set pop" : : : "memory")

#endif /* bits/atomic.h */