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, 19 insertions, 14 deletions

diff --git a/src/math/cosf.c b/src/math/cosf.c
index 4d94130f..23f3e5bf 100644
--- a/src/math/cosf.c
+++ b/src/math/cosf.c
@@ -26,34 +26,39 @@ c4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
 float cosf(float x)
 {
 	double y;
-	int32_t n, hx, ix;
+	uint32_t ix;
+	unsigned n, sign;
+
+	GET_FLOAT_WORD(ix, x);
+	sign = ix >> 31;
+	ix &= 0x7fffffff;
 
-	GET_FLOAT_WORD(hx, x);
-	ix = hx & 0x7fffffff;
 	if (ix <= 0x3f490fda) {  /* |x| ~<= pi/4 */
-		if (ix < 0x39800000)  /* |x| < 2**-12 */
-			if ((int)x == 0)  /* raise inexact if x != 0 */
-				return 1.0;
+		if (ix < 0x39800000) {  /* |x| < 2**-12 */
+			/* raise inexact if x != 0 */
+			FORCE_EVAL(x + 0x1p120f);
+			return 1.0f;
+		}
 		return __cosdf(x);
 	}
 	if (ix <= 0x407b53d1) {  /* |x| ~<= 5*pi/4 */
 		if (ix > 0x4016cbe3)  /* |x|  ~> 3*pi/4 */
-			return -__cosdf(hx > 0 ? x-c2pio2 : x+c2pio2);
+			return -__cosdf(sign ? x+c2pio2 : x-c2pio2);
 		else {
-			if (hx > 0)
-				return __sindf(c1pio2 - x);
-			else
+			if (sign)
 				return __sindf(x + c1pio2);
+			else
+				return __sindf(c1pio2 - x);
 		}
 	}
 	if (ix <= 0x40e231d5) {  /* |x| ~<= 9*pi/4 */
 		if (ix > 0x40afeddf)  /* |x| ~> 7*pi/4 */
-			return __cosdf(hx > 0 ? x-c4pio2 : x+c4pio2);
+			return __cosdf(sign ? x+c4pio2 : x-c4pio2);
 		else {
-			if (hx > 0)
-				return __sindf(x - c3pio2);
+			if (sign)
+				return __sindf(-x - c3pio2);
 			else
-				return __sindf(-c3pio2 - x);
+				return __sindf(x - c3pio2);
 		}
 	}