clean up "static" and "constexpr" types

- use `static constexpr inline' to avoid requiring
  explicit declarations in object code
- use `const Foo* const' to maybe put into readonly
  binary segment (at least for ELF DSOs)
- `constexpr' in function scope has storage, avoid
  `static'
- don't use `constexpr' where there's no advantage,
  like arrays

We'd like to avoid overhead of atomic initialization
for each function call. No idea how `static constexpr'
requiring storage in the standard plays with atomic
initialization requirement. Hearsay points that
`constexpr' without `static' in block scope behaves
more to our liking. It's all hazy though.

I'm not 100% sure if `static inline constexpr' has any
storage. Hopefully none, like a #define, and stuff
bigger than registers gets coalesced within the same
module, with small stuff being immediates.

2 files changed, 5 insertions, 6 deletions

diff --git a/logic/pipeline.cpp b/logic/pipeline.cpp
index d690b406..9059a251 100644
--- a/logic/pipeline.cpp
+++ b/logic/pipeline.cpp
@@ -190,8 +190,6 @@ static bool is_nan(const dmat<u,w>& r)
     return false;
 }
 
-constexpr double pipeline::c_mult;
-constexpr double pipeline::c_div;
 template<typename x, typename y, typename... xs>
 static inline bool nan_check_(const x& datum, const y& next, const xs&... rest)
 {
@@ -480,8 +478,9 @@ void pipeline::run()
 #endif
 
     {
-        static constexpr const char* posechannels[6] = { "TX", "TY", "TZ", "Yaw", "Pitch", "Roll" };
-        static constexpr const char* datachannels[5] = { "dt", "raw", "corrected", "filtered", "mapped" };
+        static const char* const posechannels[6] = { "TX", "TY", "TZ", "Yaw", "Pitch", "Roll" };
+        static const char* const datachannels[5] = { "dt", "raw", "corrected", "filtered", "mapped" };
+
         logger.write(datachannels[0]);
         char buffer[128];
         for (unsigned j = 1; j < 5; ++j)
diff --git a/logic/pipeline.hpp b/logic/pipeline.hpp
index 0061e439..1e1919f4 100644
--- a/logic/pipeline.hpp
+++ b/logic/pipeline.hpp
@@ -114,8 +114,8 @@ private:
     void run() override;
 
     // note: float exponent base is 2
-    static constexpr double c_mult = 16;
-    static constexpr double c_div = 1./c_mult;
+    static constexpr inline double c_mult = 16;
+    static constexpr inline double c_div = 1./c_mult;
 public:
     pipeline(Mappings& m, runtime_libraries& libs, event_handler& ev, TrackLogger& logger);
     ~pipeline();