libstdc++-v3/config/cpu/m68k/atomicity.h

[Sebastian Huber <sebastian dot huber at embedded-brains dot de>]

Hello,

for RTEMS there is a special case in:

libstdc++-v3/config/cpu/m68k/atomicity.h

[...]
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
[...]
#elif defined(__rtems__)
  // TAS/JBNE is unsafe on systems with strict priority-based scheduling.
  // Disable interrupts, which we can do only from supervisor mode.
  _Atomic_word
  __attribute__ ((__unused__))
  __exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
  {
    _Atomic_word __result;
    short __level, __tmpsr;
    __asm__ __volatile__ ("move%.w %%sr,%0\n\tor%.l %0,%1\n\tmove%.w 
%1,%%sr"
              : "=d"(__level), "=d"(__tmpsr) : "1"(0x700));

    __result = *__mem;
    *__mem = __result + __val;
    __asm__ __volatile__ ("move%.w %0,%%sr" : : "d"(__level));

    return __result;
  }

#else
[...]

Since C++14 is the default for GCC 6, would it be possible to use the 
standard atomic operations instead? For targets that don't support the 
operations in hardware, this would lead to a libatomic dependency.

--
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
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