diff options
| -rw-r--r-- | SConstruct | 5 | ||||
| -rw-r--r-- | build.txt | 19 | ||||
| -rw-r--r-- | compiler.h | 10 |
3 files changed, 22 insertions, 12 deletions
@@ -634,6 +634,11 @@ else: else: confdefs.append("/* #undef HAVE_TERMIOS_H */\n") + if config.CheckHeader("stdatomic.h"): + confdefs.append("#define HAVE_STDATOMIC_H 1\n") + else: + confdefs.append("/* #undef HAVE_STDATOMIC_H */\n") + # endian.h is required for rtcm104v2 unless the compiler defines # __ORDER_BIG_ENDIAN__, __ORDER_LITTLE_ENDIAN__ and __BYTE_ORDER__ if config.CheckCompilerDefines("__ORDER_BIG_ENDIAN__") \ @@ -58,10 +58,17 @@ arrange this by putting symlink in a local directory on $PATH. === C compiler === C99 conformance is required in the compiler. The C code depends on one -non-C99 feature (supported by GCC, clang, and pretty much any C -compiler that also speaks C++): anonymous unions. We could eliminate -these, but the cost would be source-level interface breakage if we -have to move structure members in and out of unions. +C11 feature (supported by GCC, clang, and pretty much any C compiler +that also speaks C++): anonymous unions. We could eliminate these, +but the cost would be source-level interface breakage if we have to +move structure members in and out of unions. + +Some portions of the code using shared-memory segments are improved by +the C11 stdatomic.h features for lockless concurrency. These are: the +SHM export mode in shmexport.c, the code for writing clock corrections +to NTP in ntpshm.c, and the code for reading NTP corrections in +ntpshmread.c. These features have been supported in GCC since 4.7 and +clang since 3.1. GPSD is normally built and tested with GCC. Do not compile with a version older than 4.1.1; there are several known issues with older versions, @@ -71,9 +78,7 @@ generation, (c) the option -Wno-missing-field-initializers is unavailable, leading to a flood of warnings (this is due to generated code and cannot be fixed). -The shared-memory interface relies on one GCCism, but the code is -otherwise pretty compiler-agnostic. It is reported that clang -produces a gpsd that passes all regression tests. +clang produces a gpsd that passes all regression tests. === Python === @@ -7,6 +7,8 @@ #ifndef _GPSD_COMPILER_H_ #define _GPSD_COMPILER_H_ +#include "gpsd_config.h" /* is STD_ATOMIC_H defined? */ + /* Macro for declaring function with printf-like arguments. */ # if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7) #define PRINTF_FUNC(format_index, arg_index) \ @@ -32,11 +34,9 @@ static /*@unused@*/ inline void memory_barrier(void) { #ifndef S_SPLINT_S -#if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7) - __atomic_thread_fence(__ATOMIC_SEQ_CST); -#elif (__GNUC__ == 4 && __GNUC_MINOR__ >= 4) - __sync_synchronize(); -#endif +#ifdef STD_ATOMIC_H + atomic_thread_fence(memory_order_seq_cst); +#endif /* STD_ATOMIC_H */ #endif /* S_SPLINT_S */ } |