fix: add NaN handling for math functions and update CMake to support C++17

Author: tiw302

CMakeLists.txt

@@ -4,6 +4,9 @@ project(simd-fp VERSION 1.1.1 LANGUAGES C CXX)
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_C_STANDARD_REQUIRED ON)
 
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
 # -----------------------------------------------------------------------
 # backend selection
 # the library auto-detects the backend via preprocessor macros.

docs/demo/simd_f128_wasm.wasm

@@ -61,6 +61,8 @@ SIMD_F128_INLINE simd_f128 simd_f128_exp(simd_f128 x) {
     double hi, lo;
     simd_f128_extract(x, &hi, &lo);
 
+    if (isnan(hi)) return simd_f128_from_double(NAN);
+
     // catch overflow/underflow early
     if (hi > 709.0) return simd_f128_from_double(INFINITY);
     if (hi < -745.0) return simd_f128_from_double(0.0);
@@ -231,6 +233,8 @@ SIMD_F128_INLINE simd_f128 simd_f128_atan2(simd_f128 y, simd_f128 x) {
     simd_f128_extract(y, &yhi, &ylo);
     simd_f128_extract(x, &xhi, &xlo);
 
+    if (isnan(xhi) || isnan(yhi)) return simd_f128_from_double(NAN);
+    
     if (xhi == 0.0 && yhi == 0.0) return simd_f128_from_double(0.0);
 
     if (xhi > 0.0) {