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, 18 insertions, 15 deletions

diff --git a/src/math/sinf.c b/src/math/sinf.c
index dcca67af..64e39f50 100644
--- a/src/math/sinf.c
+++ b/src/math/sinf.c
@@ -26,35 +26,38 @@ s4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
 float sinf(float x)
 {
 	double y;
-	int32_t n, hx, ix;
+	uint32_t ix;
+	int n, sign;
 
-	GET_FLOAT_WORD(hx, x);
-	ix = hx & 0x7fffffff;
+	GET_FLOAT_WORD(ix, x);
+	sign = ix >> 31;
+	ix &= 0x7fffffff;
 
 	if (ix <= 0x3f490fda) {  /* |x| ~<= pi/4 */
-		if (ix < 0x39800000)  /* |x| < 2**-12 */
-			/* raise inexact if x != 0 */
-			if((int)x == 0)
-				return x;
+		if (ix < 0x39800000) {  /* |x| < 2**-12 */
+			/* raise inexact if x!=0 and underflow if subnormal */
+			FORCE_EVAL(ix < 0x00800000 ? x/0x1p120f : x+0x1p120f);
+			return x;
+		}
 		return __sindf(x);
 	}
 	if (ix <= 0x407b53d1) {  /* |x| ~<= 5*pi/4 */
 		if (ix <= 0x4016cbe3) {  /* |x| ~<= 3pi/4 */
-			if (hx > 0)
-				return __cosdf(x - s1pio2);
-			else
+			if (sign)
 				return -__cosdf(x + s1pio2);
+			else
+				return __cosdf(x - s1pio2);
 		}
-		return __sindf(hx > 0 ? s2pio2 - x : -s2pio2 - x);
+		return __sindf(sign ? -(x + s2pio2) : -(x - s2pio2));
 	}
 	if (ix <= 0x40e231d5) {  /* |x| ~<= 9*pi/4 */
 		if (ix <= 0x40afeddf) {  /* |x| ~<= 7*pi/4 */
-			if (hx > 0)
-				return -__cosdf(x - s3pio2);
-			else
+			if (sign)
 				return __cosdf(x + s3pio2);
+			else
+				return -__cosdf(x - s3pio2);
 		}
-		return __sindf(hx > 0 ? x - s4pio2 : x + s4pio2);
+		return __sindf(sign ? x + s4pio2 : x - s4pio2);
 	}
 
 	/* sin(Inf or NaN) is NaN */