/* Linux-specific atomic operations for ARM EABI.
   Copyright (C) 2008 Free Software Foundation, Inc.
   Contributed by CodeSourcery.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

In addition to the permissions in the GNU General Public License, the
Free Software Foundation gives you unlimited permission to link the
compiled version of this file into combinations with other programs,
and to distribute those combinations without any restriction coming
from the use of this file.  (The General Public License restrictions
do apply in other respects; for example, they cover modification of
the file, and distribution when not linked into a combine
executable.)

GCC 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 General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */

/* Kernel helper for compare-and-exchange.  */
typedef int (__kernel_cmpxchg_t) (int oldval, int newval, int *ptr);
#define __kernel_cmpxchg (*(__kernel_cmpxchg_t *) 0xffff0fc0)

/* Kernel helper for memory barrier.  */
typedef void (__kernel_dmb_t) (void);
#define __kernel_dmb (*(__kernel_dmb_t *) 0xffff0fa0)

/* Note: we implement byte, short and int versions of atomic operations using
   the above kernel helpers, but there is no support for "long long" (64-bit)
   operations as yet.  */

#define HIDDEN __attribute__ ((visibility ("hidden")))

#ifdef __ARMEL__
#define INVERT_MASK_1 0
#define INVERT_MASK_2 0
#else
#define INVERT_MASK_1 24
#define INVERT_MASK_2 16
#endif

#define MASK_1 0xffu
#define MASK_2 0xffffu

#define FETCH_AND_OP_WORD(OP, PFX_OP, INF_OP)				\
  int HIDDEN								\
  __sync_fetch_and_##OP##_4 (int *ptr, int val)				\
  {									\
    int failure, tmp;							\
									\
    do {								\
      tmp = *ptr;							\
      failure = __kernel_cmpxchg (tmp, PFX_OP tmp INF_OP val, ptr);	\
    } while (failure != 0);						\
									\
    return tmp;								\
  }

FETCH_AND_OP_WORD (add,   , +)
FETCH_AND_OP_WORD (sub,   , -)
FETCH_AND_OP_WORD (or,    , |)
FETCH_AND_OP_WORD (and,   , &)
FETCH_AND_OP_WORD (xor,   , ^)
FETCH_AND_OP_WORD (nand, ~, &)

#define NAME_oldval(OP, WIDTH) __sync_fetch_and_##OP##_##WIDTH
#define NAME_newval(OP, WIDTH) __sync_##OP##_and_fetch_##WIDTH

/* Implement both __sync_<op>_and_fetch and __sync_fetch_and_<op> for
   subword-sized quantities.  */

#define SUBWORD_SYNC_OP(OP, PFX_OP, INF_OP, TYPE, WIDTH, RETURN)	\
  TYPE HIDDEN								\
  NAME##_##RETURN (OP, WIDTH) (TYPE *ptr, TYPE val)			\
  {									\
    int *wordptr = (int *) ((unsigned int) ptr & ~3);			\
    unsigned int mask, shift, oldval, newval;				\
    int failure;							\
									\
    shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;	\
    mask = MASK_##WIDTH << shift;					\
									\
    do {								\
      oldval = *wordptr;						\
      newval = ((PFX_OP ((oldval & mask) >> shift)			\
                 INF_OP (unsigned int) val) << shift) & mask;		\
      newval |= oldval & ~mask;						\
      failure = __kernel_cmpxchg (oldval, newval, wordptr);		\
    } while (failure != 0);						\
									\
    return (RETURN & mask) >> shift;					\
  }

SUBWORD_SYNC_OP (add,   , +, short, 2, oldval)
SUBWORD_SYNC_OP (sub,   , -, short, 2, oldval)
SUBWORD_SYNC_OP (or,    , |, short, 2, oldval)
SUBWORD_SYNC_OP (and,   , &, short, 2, oldval)
SUBWORD_SYNC_OP (xor,   , ^, short, 2, oldval)
SUBWORD_SYNC_OP (nand, ~, &, short, 2, oldval)

SUBWORD_SYNC_OP (add,   , +, char, 1, oldval)
SUBWORD_SYNC_OP (sub,   , -, char, 1, oldval)
SUBWORD_SYNC_OP (or,    , |, char, 1, oldval)
SUBWORD_SYNC_OP (and,   , &, char, 1, oldval)
SUBWORD_SYNC_OP (xor,   , ^, char, 1, oldval)
SUBWORD_SYNC_OP (nand, ~, &, char, 1, oldval)

#define OP_AND_FETCH_WORD(OP, PFX_OP, INF_OP)				\
  int HIDDEN								\
  __sync_##OP##_and_fetch_4 (int *ptr, int val)				\
  {									\
    int tmp, failure;							\
									\
    do {								\
      tmp = *ptr;							\
      failure = __kernel_cmpxchg (tmp, PFX_OP tmp INF_OP val, ptr);	\
    } while (failure != 0);						\
									\
    return PFX_OP tmp INF_OP val;					\
  }

OP_AND_FETCH_WORD (add,   , +)
OP_AND_FETCH_WORD (sub,   , -)
OP_AND_FETCH_WORD (or,    , |)
OP_AND_FETCH_WORD (and,   , &)
OP_AND_FETCH_WORD (xor,   , ^)
OP_AND_FETCH_WORD (nand, ~, &)

SUBWORD_SYNC_OP (add,   , +, short, 2, newval)
SUBWORD_SYNC_OP (sub,   , -, short, 2, newval)
SUBWORD_SYNC_OP (or,    , |, short, 2, newval)
SUBWORD_SYNC_OP (and,   , &, short, 2, newval)
SUBWORD_SYNC_OP (xor,   , ^, short, 2, newval)
SUBWORD_SYNC_OP (nand, ~, &, short, 2, newval)

SUBWORD_SYNC_OP (add,   , +, char, 1, newval)
SUBWORD_SYNC_OP (sub,   , -, char, 1, newval)
SUBWORD_SYNC_OP (or,    , |, char, 1, newval)
SUBWORD_SYNC_OP (and,   , &, char, 1, newval)
SUBWORD_SYNC_OP (xor,   , ^, char, 1, newval)
SUBWORD_SYNC_OP (nand, ~, &, char, 1, newval)

int HIDDEN
__sync_val_compare_and_swap_4 (int *ptr, int oldval, int newval)
{
  int actual_oldval, fail;
    
  while (1)
    {
      actual_oldval = *ptr;

      if (oldval != actual_oldval)
	return actual_oldval;

      fail = __kernel_cmpxchg (actual_oldval, newval, ptr);
  
      if (!fail)
        return oldval;
    }
}

#define SUBWORD_VAL_CAS(TYPE, WIDTH)					\
  TYPE HIDDEN								\
  __sync_val_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval,		\
				       TYPE newval)			\
  {									\
    int *wordptr = (int *)((unsigned int) ptr & ~3), fail;		\
    unsigned int mask, shift, actual_oldval, actual_newval;		\
									\
    shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;	\
    mask = MASK_##WIDTH << shift;					\
									\
    while (1)								\
      {									\
	actual_oldval = *wordptr;					\
									\
	if (((actual_oldval & mask) >> shift) != (unsigned int) oldval)	\
          return (actual_oldval & mask) >> shift;			\
									\
	actual_newval = (actual_oldval & ~mask)				\
			| (((unsigned int) newval << shift) & mask);	\
									\
	fail = __kernel_cmpxchg (actual_oldval, actual_newval,		\
				 wordptr);				\
									\
	if (!fail)							\
          return oldval;						\
      }									\
  }

SUBWORD_VAL_CAS (short, 2)
SUBWORD_VAL_CAS (char,  1)

typedef unsigned char bool;

bool HIDDEN
__sync_bool_compare_and_swap_4 (int *ptr, int oldval, int newval)
{
  int failure = __kernel_cmpxchg (oldval, newval, ptr);
  return (failure == 0);
}

#define SUBWORD_BOOL_CAS(TYPE, WIDTH)					\
  bool HIDDEN								\
  __sync_bool_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval,		\
					TYPE newval)			\
  {									\
    TYPE actual_oldval							\
      = __sync_val_compare_and_swap_##WIDTH (ptr, oldval, newval);	\
    return (oldval == actual_oldval);					\
  }

SUBWORD_BOOL_CAS (short, 2)
SUBWORD_BOOL_CAS (char,  1)

void HIDDEN
__sync_synchronize (void)
{
  __kernel_dmb ();
}

int HIDDEN
__sync_lock_test_and_set_4 (int *ptr, int val)
{
  int failure, oldval;

  do {
    oldval = *ptr;
    failure = __kernel_cmpxchg (oldval, val, ptr);
  } while (failure != 0);

  return oldval;
}

#define SUBWORD_TEST_AND_SET(TYPE, WIDTH)				\
  TYPE HIDDEN								\
  __sync_lock_test_and_set_##WIDTH (TYPE *ptr, TYPE val)		\
  {									\
    int failure;							\
    unsigned int oldval, newval, shift, mask;				\
    int *wordptr = (int *) ((unsigned int) ptr & ~3);			\
									\
    shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;	\
    mask = MASK_##WIDTH << shift;					\
									\
    do {								\
      oldval = *wordptr;						\
      newval = (oldval & ~mask)						\
	       | (((unsigned int) val << shift) & mask);		\
      failure = __kernel_cmpxchg (oldval, newval, wordptr);		\
    } while (failure != 0);						\
									\
    return (oldval & mask) >> shift;					\
  }

SUBWORD_TEST_AND_SET (short, 2)
SUBWORD_TEST_AND_SET (char,  1)

#define SYNC_LOCK_RELEASE(TYPE, WIDTH)					\
  void HIDDEN								\
  __sync_lock_release_##WIDTH (TYPE *ptr)				\
  {									\
    *ptr = 0;								\
    __kernel_dmb ();							\
  }

SYNC_LOCK_RELEASE (int,   4)
SYNC_LOCK_RELEASE (short, 2)
SYNC_LOCK_RELEASE (char,  1)