Library: better short-hand name for long double

As with all those C++ base types, unfortunately they are giving you
only rough size guarantees. For Lumiera, I defined short hand names
some time ago, notably because the explicit long X and short X qualifiers
do not work with ''constructor syntax'' for direct conversions.

But I choose the name `f128` at that time -- which might raise ill-guided
expectations, since the `long double` is not that long on relevant linux 64bit
platforms; it can just hold 64bit of mantissa at least however.

As replacement, I'll use `lflp` now, because it has also 4 letters,
looks somewhat weird (and thus catches attention) and points into the
right direction. I considered `lfloat` as alternative, but that looks
too much like `float`, visually...

src/lib/format-obj.cpp

@@ -363,11 +363,11 @@ namespace util {
   
   string showDecimal (double val)  noexcept { return showFloatingPoint (val, PRECISION_DECIMAL<double>); }
   string showDecimal (float val)   noexcept { return showFloatingPoint (val, PRECISION_DECIMAL<float>); }
-  string showDecimal (f128 val)    noexcept { return showFloatingPoint (val, PRECISION_DECIMAL<f128>); }
+  string showDecimal (lflp val)    noexcept { return showFloatingPoint (val, PRECISION_DECIMAL<lflp>); }
   
   string showComplete (double val) noexcept { return showFloatingPoint (val, PRECISION_COMPLETE<double>); }
   string showComplete (float val)  noexcept { return showFloatingPoint (val, PRECISION_COMPLETE<float>); }
-  string showComplete (f128 val)   noexcept { return showFloatingPoint (val, PRECISION_COMPLETE<f128>); }
+  string showComplete (lflp val)   noexcept { return showFloatingPoint (val, PRECISION_COMPLETE<lflp>); }
   
   
   string

src/lib/format-obj.hpp

@@ -93,10 +93,10 @@ namespace util {
   
   std::string showDecimal (double) noexcept;
   std::string showDecimal (float)  noexcept;
-  std::string showDecimal (f128)   noexcept;
+  std::string showDecimal (lflp)   noexcept;
   std::string showComplete (double)noexcept;
   std::string showComplete (float) noexcept;
-  std::string showComplete (f128)  noexcept;
+  std::string showComplete (lflp)  noexcept;
   
   
   

src/lib/integral.hpp

@@ -32,8 +32,8 @@ using llong = long long int;
 using ullong = unsigned long long int;
 using ushort = unsigned short int;
 
-using f128  = long double;
-static_assert(10 <= sizeof(f128));
+using lflp  = long double;
+static_assert(10 <= sizeof(lflp));
 
 const uint LIFE_AND_UNIVERSE_4EVER = 42;
 

src/lib/meta/util.hpp

@@ -456,12 +456,12 @@ namespace util {
   /** show maximum reproducible decimal representation */
   std::string showDecimal (double) noexcept;
   std::string showDecimal (float)  noexcept;
-  std::string showDecimal (f128)   noexcept;
+  std::string showDecimal (lflp)   noexcept;
   
   /** show enough decimal digits to represent every distinct value */
   std::string showComplete (double) noexcept;
   std::string showComplete (float)  noexcept;
-  std::string showComplete (f128)   noexcept;
+  std::string showComplete (lflp)   noexcept;
   
   std::string showSize (size_t)   noexcept;
   

src/lib/par/type-handler.hpp

@@ -180,11 +180,14 @@ _Pragma("GCC diagnostic pop")
           if constexpr (8 > sizeof(U))
               return std::type_identity<int64_t>{};
           else
-              return std::type_identity<f128>{};
+              return std::type_identity<lflp>{};
               // no standard integral type can hold uint64_t's full range signed.
               // Expand to long double, which can hold 64bit without precision loss
         }
     }
+    
+    static_assert (64 <= std::numeric_limits<lflp>::digits
+                  ,"long double type can not represent uint64_t exactly");
   }
   
   /**

src/lib/rational.hpp

@@ -122,12 +122,12 @@ namespace util {
     u = 0!=u? u:1;
     auto [d,r] = util::iDiv (num, den);
     // round to smallest integer fraction, to shake off "number dust"
-    f128 const ROUND_ULP = 1 + 1/(f128(std::numeric_limits<int64_t>::max()) * 2);
+    lflp const ROUND_ULP = 1 + 1/(lflp(std::numeric_limits<int64_t>::max()) * 2);
     
     // construct approximation quantised to 1/u
-    f128 frac = f128(r) / den;
+    lflp frac = lflp(r) / den;
     int64_t res = d*u + int64_t(frac*u * ROUND_ULP);
-    ENSURE (abs (f128(res)/u - rational_cast<f128>(Rat{num,den})) <= 1.0/abs(u)
+    ENSURE (abs (lflp(res)/u - rational_cast<lflp>(Rat{num,den})) <= 1.0/abs(u)
            ,"Requantisation error exceeded num=%li / den=%li -> res=%li / quant=%li"
            ,                                   num,       den,       res,        u);
     return res;

tests/lib/cyclic-wrap-test.cpp

@@ -76,7 +76,7 @@ namespace test {
           
           verifyFloatTypes<float>();
           verifyFloatTypes<double>();
-          verifyFloatTypes<f128>();
+          verifyFloatTypes<lflp>();
         }
       
       

tests/lib/par/parameter-scale-test.cpp

@@ -134,7 +134,7 @@ namespace test{
           CHECK ( 15 == angleScale.conform(65535));
 
           
-          Scale<f128> tinyScale = {.minVal=-f128(1)/100, .maxVal=f128(1)/100};
+          Scale<lflp> tinyScale = {.minVal=-lflp(1)/100, .maxVal=lflp(1)/100};
           tinyScale.cyclicLim = util::limit_cyclicWrap(*tinyScale.maxVal - *tinyScale.minVal);
           CHECK (1e16 < tinyScale.cyclicLim);
           CHECK (tinyScale.isValid());

tests/lib/stat/data-csv-test.cpp

@@ -224,7 +224,7 @@ namespace test{
           
           CHECK (format4Csv(double(1) / 3) == "0.333333333333333"_expect   );
           CHECK (format4Csv(float(1) / 3)  == "0.333333"_expect            );
-          CHECK (format4Csv(f128(1) / 3)   == "0.333333333333333333"_expect);
+          CHECK (format4Csv(lflp(1) / 3)   == "0.333333333333333333"_expect);
           CHECK (format4Csv(bool(1))       == "true"_expect );
           CHECK (format4Csv(bool(0))       == "false"_expect);
           CHECK (format4Csv("Starship-3")  == "\"Starship-3\""_expect ); // 3rd test today ;-)

tests/vault/mem/engine-buffer-manager-test.cpp

@@ -92,9 +92,9 @@ namespace test  {
           CHECK (a2.siz > 555);
           
           // can use that memory without blowing up....
-          auto doooh = new(a1.mem) f128{std::numeric_limits<f128>::max()};
+          auto doooh = new(a1.mem) lflp{std::numeric_limits<lflp>::max()};
           *doooh /= 2;
-          CHECK (2 == std::numeric_limits<f128>::max() / *doooh);
+          CHECK (2 == std::numeric_limits<lflp>::max() / *doooh);
           
           allo.deallocate (a1);
           allo.deallocate (a2);