1 files changed, 11 insertions, 26 deletions
diff --git a/src/math/tanl.c b/src/math/tanl.c
index 0194eaf7..3b51e011 100644
--- a/src/math/tanl.c
+++ b/src/math/tanl.c
@@ -41,42 +41,27 @@ long double tanl(long double x)
 long double tanl(long double x)
 {
 	union IEEEl2bits z;
-	int e0, s;
 	long double y[2];
-	long double hi, lo;
+	unsigned n;
 
 	z.e = x;
-	s = z.bits.sign;
 	z.bits.sign = 0;
 
-	/* If x = +-0 or x is subnormal, then tan(x) = x. */
-	if (z.bits.exp == 0)
-		return x;
-
 	/* If x = NaN or Inf, then tan(x) = NaN. */
-	if (z.bits.exp == 32767)
+	if (z.bits.exp == 0x7fff)
 		return (x - x) / (x - x);
 
-	/* Optimize the case where x is already within range. */
+	/* |x| < (double)pi/4 */
 	if (z.e < M_PI_4) {
-		hi = __tanl(z.e, 0, 0);
-		return s ? -hi : hi;
+		/* x = +-0 or x is subnormal */
+		if (z.bits.exp == 0)
+			/* inexact and underflow if x!=0 */
+			return x + x*0x1p-120f;
+		/* can raise spurious underflow */
+		return __tanl(x, 0, 0);
 	}
 
-	e0 = __rem_pio2l(x, y);
-	hi = y[0];
-	lo = y[1];
-
-	switch (e0 & 3) {
-	case 0:
-	case 2:
-		hi = __tanl(hi, lo, 0);
-		break;
-	case 1:
-	case 3:
-		hi = __tanl(hi, lo, 1);
-		break;
-	}
-	return hi;
+	n = __rem_pio2l(x, y);
+	return __tanl(y[0], y[1], n&1);
 }
 #endif