Add fmin/fmax functions to math.h

mos-platform/common/c/CMakeLists.txt

@@ -12,6 +12,9 @@ add_platform_library(common-c
   # inttypes.h
   inttypes.c
 
+  # math.h
+  math.cc
+
   # setjmp.h
   setjmp.S
 

mos-platform/common/c/math.cc

@@ -0,0 +1,20 @@
+#include <math.h>
+
+template <typename T> static inline T _fmax(const T x, const T y) {
+  if (isnan(y)) return x;
+  // if x is nan, then x > y is false, so the ternary returns y
+  return x > y ? x : y;
+}
+
+template <typename T> static inline T _fmin(const T x, const T y) {
+  if (isnan(y)) return x;
+  // if x is nan, then x < y is false, so the ternary returns y
+  return x < y ? x : y;
+}
+
+extern "C" {
+double fmin(double x, double y) { return _fmin<double>(x, y); }
+double fmax(double x, double y) { return _fmax<double>(x, y); }
+float fminf(float x, float y) { return _fmin<float>(x, y); }
+float fmaxf(float x, float y) { return _fmax<float>(x, y); }
+}

mos-platform/common/include/math.h

@@ -17,6 +17,13 @@ extern "C" {
 
 #define INFINITY (1.0f / 0.0f)
 
+#define isnan(arg) __builtin_isnan(arg)
+
+double fmin(double x, double y);
+double fmax(double x, double y);
+float fminf(float x, float y);
+float fmaxf(float x, float y);
+
 #ifdef __cplusplus
 }
 #endif