X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fmath%2Fpowf.c;h=427c8965b9e8e78bca69660427a4e313087c3e0a;hp=e322ff28bce1e48bff3d21f8945257c449ca86f9;hb=04ccbdca6d88738e23e0d6a622ad33854c468646;hpb=b69f695acedd4ce2798ef9ea28d834ceccc789bd

diff --git a/src/math/powf.c b/src/math/powf.c
index e322ff28..427c8965 100644
--- a/src/math/powf.c
+++ b/src/math/powf.c
@@ -19,9 +19,6 @@ static const float
 bp[]   = {1.0, 1.5,},
 dp_h[] = { 0.0, 5.84960938e-01,}, /* 0x3f15c000 */
 dp_l[] = { 0.0, 1.56322085e-06,}, /* 0x35d1cfdc */
-zero   =  0.0,
-one    =  1.0,
-two    =  2.0,
 two24  =  16777216.0,  /* 0x4b800000 */
 huge   =  1.0e30,
 tiny   =  1.0e-30,
@@ -60,17 +57,15 @@ float powf(float x, float y)
 	ix = hx & 0x7fffffff;
 	iy = hy & 0x7fffffff;
 
-	/* y == zero: x**0 = 1 */
+	/* x**0 = 1, even if x is NaN */
 	if (iy == 0)
-		return one;
-
-	/* x == 1: 1**y = 1, even if y is NaN */
+		return 1.0f;
+	/* 1**y = 1, even if y is NaN */
 	if (hx == 0x3f800000)
-		return one;
-
-	/* y != zero: result is NaN if either arg is NaN */
+		return 1.0f;
+	/* NaN if either arg is NaN */
 	if (ix > 0x7f800000 || iy > 0x7f800000)
-		return (x+0.0F) + (y+0.0F);
+		return x + y;
 
 	/* determine if y is an odd int when x < 0
 	 * yisint = 0       ... y is not an integer
@@ -92,17 +87,14 @@ float powf(float x, float y)
 	/* special value of y */
 	if (iy == 0x7f800000) {  /* y is +-inf */
 		if (ix == 0x3f800000)      /* (-1)**+-inf is 1 */
-			return one;
+			return 1.0f;
 		else if (ix > 0x3f800000)  /* (|x|>1)**+-inf = inf,0 */
-			return hy >= 0 ? y : zero;
+			return hy >= 0 ? y : 0.0f;
 		else                       /* (|x|<1)**+-inf = 0,inf */
-			return hy < 0 ? -y : zero;
-	}
-	if (iy == 0x3f800000) {  /* y is +-1 */
-		if (hy < 0)
-			return one/x;
-		return x;
+			return hy >= 0 ? 0.0f: -y;
 	}
+	if (iy == 0x3f800000)    /* y is +-1 */
+		return hy >= 0 ? x : 1.0f/x;
 	if (hy == 0x40000000)    /* y is 2 */
 		return x*x;
 	if (hy == 0x3f000000) {  /* y is  0.5 */
@@ -115,7 +107,7 @@ float powf(float x, float y)
 	if (ix == 0x7f800000 || ix == 0 || ix == 0x3f800000) { /* x is +-0,+-inf,+-1 */
 		z = ax;
 		if (hy < 0)  /* z = (1/|x|) */
-			z = one/z;
+			z = 1.0f/z;
 		if (hx < 0) {
 			if (((ix-0x3f800000)|yisint) == 0) {
 				z = (z-z)/(z-z); /* (-1)**non-int is NaN */
@@ -125,15 +117,13 @@ float powf(float x, float y)
 		return z;
 	}
 
-	n = ((uint32_t)hx>>31) - 1;
-
-	/* (x<0)**(non-int) is NaN */
-	if ((n|yisint) == 0)
-		return (x-x)/(x-x);
-
-	sn = one; /* s (sign of result -ve**odd) = -1 else = 1 */
-	if ((n|(yisint-1)) == 0)  /* (-ve)**(odd int) */
-		sn = -one;
+	sn = 1.0f; /* sign of result */
+	if (hx < 0) {
+		if (yisint == 0) /* (x<0)**(non-int) is NaN */
+			return (x-x)/(x-x);
+		if (yisint == 1) /* (x<0)**(odd int) */
+			sn = -1.0f;
+	}
 
 	/* |y| is huge */
 	if (iy > 0x4d000000) { /* if |y| > 2**27 */
@@ -145,7 +135,7 @@ float powf(float x, float y)
 		/* now |1-x| is tiny <= 2**-20, suffice to compute
 		   log(x) by x-x^2/2+x^3/3-x^4/4 */
 		t = ax - 1;     /* t has 20 trailing zeros */
-		w = (t*t)*((float)0.5-t*((float)0.333333333333-t*(float)0.25));
+		w = (t*t)*(0.5f - t*(0.333333333333f - t*0.25f));
 		u = ivln2_h*t;  /* ivln2_h has 16 sig. bits */
 		v = t*ivln2_l - w*ivln2;
 		t1 = u + v;
@@ -178,7 +168,7 @@ float powf(float x, float y)
 
 		/* compute s = s_h+s_l = (x-1)/(x+1) or (x-1.5)/(x+1.5) */
 		u = ax - bp[k];   /* bp[0]=1.0, bp[1]=1.5 */
-		v = one/(ax+bp[k]);
+		v = 1.0f/(ax+bp[k]);
 		s = u*v;
 		s_h = s;
 		GET_FLOAT_WORD(is, s_h);
@@ -193,10 +183,10 @@ float powf(float x, float y)
 		r = s2*s2*(L1+s2*(L2+s2*(L3+s2*(L4+s2*(L5+s2*L6)))));
 		r += s_l*(s_h+s);
 		s2 = s_h*s_h;
-		t_h = (float)3.0 + s2 + r;
+		t_h = 3.0f + s2 + r;
 		GET_FLOAT_WORD(is, t_h);
 		SET_FLOAT_WORD(t_h, is & 0xfffff000);
-		t_l = r - ((t_h - (float)3.0) - s2);
+		t_l = r - ((t_h - 3.0f) - s2);
 		/* u+v = s*(1+...) */
 		u = s_h*t_h;
 		v = s_l*t_h + t_l*s;
@@ -257,8 +247,8 @@ float powf(float x, float y)
 	w = v - (z - u);
 	t = z*z;
 	t1 = z - t*(P1+t*(P2+t*(P3+t*(P4+t*P5))));
-	r = (z*t1)/(t1-two) - (w+z*w);
-	z = one - (r - z);
+	r = (z*t1)/(t1-2.0f) - (w+z*w);
+	z = 1.0f - (r - z);
 	GET_FLOAT_WORD(j, z);
 	j += n<<23;
 	if ((j>>23) <= 0)  /* subnormal output */