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, 11 insertions, 9 deletions

diff --git a/src/math/sincosl.c b/src/math/sincosl.c
index d632fe6f..5db69bd6 100644
--- a/src/math/sincosl.c
+++ b/src/math/sincosl.c
@@ -10,27 +10,29 @@ void sincosl(long double x, long double *sin, long double *cos)
 void sincosl(long double x, long double *sin, long double *cos)
 {
 	union IEEEl2bits u;
-	int n;
+	unsigned n;
 	long double y[2], s, c;
 
 	u.e = x;
 	u.bits.sign = 0;
 
-	/* x = +-0 or subnormal */
-	if (!u.bits.exp) {
-		*sin = x;
-		*cos = 1.0;
-		return;
-	}
-
 	/* x = nan or inf */
 	if (u.bits.exp == 0x7fff) {
 		*sin = *cos = x - x;
 		return;
 	}
 
-	/* |x| < pi/4 */
+	/* |x| < (double)pi/4 */
 	if (u.e < M_PI_4) {
+		/* |x| < 0x1p-64 */
+		if (u.bits.exp < 0x3fff - 64) {
+			/* raise underflow if subnormal */
+			if (u.bits.exp == 0) FORCE_EVAL(x*0x1p-120f);
+			*sin = x;
+			/* raise inexact if x!=0 */
+			*cos = 1.0 + x;
+			return;
+		}
 		*sin = __sinl(x, 0, 0);
 		*cos = __cosl(x, 0);
 		return;