usermode/library/atomic_ops/sparc.h

/*
 * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
 * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
 * Copyright (c) 1999-2003 by Hewlett-Packard Company. All rights reserved.
 *
 *
 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 *
 * Permission is hereby granted to use or copy this program
 * for any purpose,  provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 *
 */

/* FIXME.  Very incomplete.  No support for sparc64.    */
/* Non-ancient SPARCs provide compare-and-swap (casa).  */
/* We should make that available.                       */

#include "./aligned_atomic_load_store.h"

/* Real SPARC code uses TSO:                            */
#include "./ordered_except_wr.h"

/* Test_and_set location is just a byte.                */
#include "./test_and_set_t_is_char.h"

AO_INLINE AO_TS_VAL_t
AO_test_and_set_full(volatile AO_TS_t *addr) {
   AO_TS_VAL_t oldval;

   __asm__ __volatile__("ldstub %1,%0"
                        : "=r"(oldval), "=m"(*addr)
                        : "m"(*addr) : "memory");
   return oldval;
}

#define AO_HAVE_test_and_set_full

#ifndef AO_NO_SPARC_V9
/* Returns nonzero if the comparison succeeded. */
AO_INLINE int
AO_compare_and_swap_full(volatile AO_t *addr, AO_t old, AO_t new_val) {
  char ret;
  __asm__ __volatile__ ("membar #StoreLoad | #LoadLoad\n\t"
#                       if defined(__arch64__)
                          "casx [%2],%0,%1\n\t"
#                       else
                          "cas [%2],%0,%1\n\t" /* 32-bit version */
#                       endif
                        "membar #StoreLoad | #StoreStore\n\t"
                        "cmp %0,%1\n\t"
                        "be,a 0f\n\t"
                        "mov 1,%0\n\t"/* one insn after branch always executed */
                        "clr %0\n\t"
                        "0:\n\t"
                        : "=r" (ret), "+r" (new_val)
                        : "r" (addr), "0" (old)
                        : "memory", "cc");
  return (int)ret;
}

#define AO_HAVE_compare_and_swap_full
#endif /* AO_NO_SPARC_V9 */

/* FIXME: This needs to be extended for SPARC v8 and v9.        */
/* SPARC V8 also has swap.  V9 has CAS.                         */
/* There are barriers like membar #LoadStore.                   */
/* CASA (32-bit) and CASXA(64-bit) instructions were            */
/* added in V9.                                                 */

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