outline details from C18 annex F

1 files changed, 23 insertions, 1 deletions

diff --git a/src/math/fma.c b/src/math/fma.c
index 18b059d1..845afea4 100644
--- a/src/math/fma.c
+++ b/src/math/fma.c
@@ -1,10 +1,32 @@
 # define TGSOURCE "fma.c"
 #include "_tgmath.h"
 #include <math.h>
+#include "fenv.h"
 
 TYPE TGFN(fma)(TYPE x, TYPE y, TYPE z)
 {
-	return x - y - z;
+	int classx = fpclassify(x);
+	int classy = fpclassify(y);
+	/* int classz = fpclassify(z); */
+
+	if (classx == FP_INFINITE && classy == FP_ZERO) {
+		feraiseexcept(FE_INVALID);
+		return NAN;
+	}
+
+	if (classx == FP_ZERO && classy == FP_INFINITE) {
+		feraiseexcept(FE_INVALID);
+		return NAN;
+	}
+
+	/*
+	if (x * y == -z && fpclassify(x*y) == classz == FP_INFINITE) {
+		feraiseexcept(FE_INVALID);
+		return NAN;
+	}
+	*/
+
+	return x * y + z;
 }
 
 /*