Merge pull request #62 from jcowgill/atomics-cleanup

Atomics cleanup

config/Makefile.am

@@ -1,7 +1,7 @@
 # We don't actually build anything in the `cpu' and `os'
 # subdirectories.
 
-DIST_SUBDIRS = cpu os sysdeps
+DIST_SUBDIRS = os sysdeps
 
 EXTRA_DIST = depcomp
 MAINTAINERCLEANFILES = Makefile.in config.guess config.sub \

config/sysdeps/Makefile.am

@@ -7,7 +7,6 @@ MAINTAINERCLEANFILES = Makefile.in
 noinst_HEADERS =		\
         systemtest.c            \
         sanitycheck.c           \
-	atomicity.h		\
 	getopt.h		\
 	ipc.h			\
 	mach_port.h		\

configure.ac

@@ -964,10 +964,6 @@ AM_CONDITIONAL(HAVE_ZITA_BRIDGE_DEPS, $HAVE_ZITA_BRIDGE_DEPS)
 AC_OUTPUT(
 Makefile
 config/Makefile
-config/cpu/Makefile
-config/cpu/generic/Makefile
-config/cpu/i386/Makefile
-config/cpu/powerpc/Makefile
 config/os/Makefile
 config/os/generic/Makefile
 config/os/gnu-linux/Makefile

doc/porting.dox

@@ -88,25 +88,6 @@ Be sure to place any generic implementation alternative in the @c
 \#else or use an @c \#ifndef, so no other code needs to know your
 conditional labels.
 
-@section portcpu Processor Dependencies
-
-JACK uses some low-level machine operations for thread-safe updates to
-shared memory.  A low-level implementation of @c <sysdeps/atomicity.h>
-is provided for every target processor architecture.  There is also a
-generic implementation using POSIX spin locks, but that is not a good
-enough solution for serious use.
-
-The GCC package provides versions that work on most modern hardware.
-We've tried to keep things as close to the original as possible, while
-removing a bunch of os-specific files that didn't seem relevant.  A
-primary goal has been to avoid changing the CPU-dependent @c
-<sysdeps/atomicity.h> headers.
-
-The relevant GCC documentation provides some helpful background,
-especially the @c atomicity.h discussion at
-<http://gcc.gnu.org/onlinedocs/porting/Thread-safety.html>.
-
-
 @section portissues Issues Not Addressed
 
   - Cross-compilation has not been tested, or even thought through in

include/atomicity.h

@@ -20,19 +20,26 @@
 #ifndef __jack_atomicity_h__
 #define __jack_atomicity_h__
 
-/*
- * Interface with various machine-dependent headers derived from the
- * gcc/libstdc++.v3 sources.  We try to modify the GCC sources as
- * little as possible.  The following include is resolved using the
- * config/configure.hosts mechanism.  It will use an OS-dependent
- * version if available, otherwise the one for this CPU.  Some of
- * these files might not work with older GCC compilers.
- */
-#include <sysdeps/atomicity.h>
+#if __STDC_VERSION__ >= 201112L && !defined(__STDC_NO_ATOMICS__)
+
+#include <stdatomic.h>
+
+typedef atomic_int _Atomic_word;
+
+static inline int exchange_and_add(volatile _Atomic_word* obj, int value)
+{
+    return atomic_fetch_add_explicit(obj, value, memory_order_relaxed);
+}
+
+#else
+
+typedef int _Atomic_word;
+
+static inline int exchange_and_add(volatile _Atomic_word* obj, int value)
+{
+    return __atomic_fetch_add(obj, value, __ATOMIC_RELAXED);
+}
 
-/* These functions are defined for each platform.  The C++ library
- * function names start with "__" to avoid namespace pollution. */
-#define exchange_and_add __exchange_and_add
-#define atomic_add __atomic_add
+#endif
 
 #endif /* __jack_atomicity_h__ */

include/internal.h

@@ -60,7 +60,7 @@ void jack_set_clock_source (jack_timer_type_t);
 const char* jack_clock_source_name (jack_timer_type_t);
 
 #include <sysdeps/time.h>
-#include <sysdeps/atomicity.h>
+#include "atomicity.h"
 
 #ifdef JACK_USE_MACH_THREADS
 #include <sysdeps/mach_port.h>

libjack/messagebuffer.c

@@ -161,7 +161,7 @@ jack_messagebuffer_add (const char *fmt, ...)
 		pthread_cond_signal (&mb_ready_cond);
 		pthread_mutex_unlock (&mb_write_lock);
 	} else {                        /* lock collision */
-		atomic_add (&mb_overruns, 1);
+		exchange_and_add (&mb_overruns, 1);
 	}
 }