math: sin cos cleanup

* use unsigned arithmetics
* use unsigned to store arg reduction quotient (so n&3 is understood)
* remove z=0.0 variables, use literal 0
* raise underflow and inexact exceptions properly when x is small
* fix spurious underflow in tanl

1 files changed, 6 insertions, 6 deletions

diff --git a/src/math/sincos.c b/src/math/sincos.c
index 442e285e..49f8a098 100644
--- a/src/math/sincos.c
+++ b/src/math/sincos.c
@@ -15,7 +15,8 @@
 void sincos(double x, double *sin, double *cos)
 {
 	double y[2], s, c;
-	uint32_t n, ix;
+	uint32_t ix;
+	unsigned n;
 
 	GET_HIGH_WORD(ix, x);
 	ix &= 0x7fffffff;
@@ -24,11 +25,10 @@ void sincos(double x, double *sin, double *cos)
 	if (ix <= 0x3fe921fb) {
 		/* if |x| < 2**-27 * sqrt(2) */
 		if (ix < 0x3e46a09e) {
-			/* raise inexact if x != 0 */
-			if ((int)x == 0) {
-				*sin = x;
-				*cos = 1.0;
-			}
+			/* raise inexact if x!=0 and underflow if subnormal */
+			FORCE_EVAL(ix < 0x00100000 ? x/0x1p120f : x+0x1p120f);
+			*sin = x;
+			*cos = 1.0;
 			return;
 		}
 		*sin = __sin(x, 0.0, 0);