X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fmath%2Flgammaf_r.c;h=c5b43db558c2a8ae1fca30847c882157d2e076e9;hb=b72cd07f176b876aa51864d93aa8101477b1d732;hp=c6280f5be41d509202f34a8d9a19243ed55e6f89;hpb=93a50a26cd0f9efc59cc83daae7b2d916b327ab1;p=musl

diff --git a/src/math/lgammaf_r.c b/src/math/lgammaf_r.c
index c6280f5b..c5b43db5 100644
--- a/src/math/lgammaf_r.c
+++ b/src/math/lgammaf_r.c
@@ -14,11 +14,9 @@
  */
 
 #include "libm.h"
+#include "libc.h"
 
 static const float
-two23= 8.3886080000e+06, /* 0x4b000000 */
-half=  5.0000000000e-01, /* 0x3f000000 */
-one =  1.0000000000e+00, /* 0x3f800000 */
 pi  =  3.1415927410e+00, /* 0x40490fdb */
 a0  =  7.7215664089e-02, /* 0x3d9e233f */
 a1  =  3.2246702909e-01, /* 0x3ea51a66 */
@@ -83,89 +81,58 @@ w4  = -5.9518753551e-04, /* 0xba1c065c */
 w5  =  8.3633989561e-04, /* 0x3a5b3dd2 */
 w6  = -1.6309292987e-03; /* 0xbad5c4e8 */
 
-static const float zero = 0.0000000000e+00;
-
-static float sin_pif(float x)
+/* sin(pi*x) assuming x > 2^-100, if sin(pi*x)==0 the sign is arbitrary */
+static float sin_pi(float x)
 {
-	float y,z;
-	int n,ix;
-
-	GET_FLOAT_WORD(ix, x);
-	ix &= 0x7fffffff;
-
-	if(ix < 0x3e800000)
-		return __sindf(pi*x);
+	double_t y;
+	int n;
 
-	y = -x;  /* negative x is assumed */
+	/* spurious inexact if odd int */
+	x = 2*(x*0.5f - floorf(x*0.5f));  /* x mod 2.0 */
 
-	/*
-	 * argument reduction, make sure inexact flag not raised if input
-	 * is an integer
-	 */
-	z = floorf(y);
-	if (z != y) {   /* inexact anyway */
-		y *= 0.5f;
-		y  = 2.0f*(y - floorf(y));   /* y = |x| mod 2.0 */
-		n  = (int)(y*4.0f);
-	} else {
-		if (ix >= 0x4b800000) {
-			y = zero;  /* y must be even */
-			n = 0;
-		} else {
-			if (ix < 0x4b000000)
-				z = y + two23;  /* exact */
-			GET_FLOAT_WORD(n, z);
-			n &= 1;
-			y = n;
-			n <<= 2;
-		}
-	}
+	n = (int)(x*4);
+	n = (n+1)/2;
+	y = x - n*0.5f;
+	y *= 3.14159265358979323846;
 	switch (n) {
-	case 0:  y =  __sindf(pi*y); break;
-	case 1:
-	case 2:  y =  __cosdf(pi*(0.5f - y)); break;
-	case 3:
-	case 4:  y =  __sindf(pi*(one - y)); break;
-	case 5:
-	case 6:  y = -__cosdf(pi*(y - 1.5f)); break;
-	default: y =  __sindf(pi*(y - 2.0f)); break;
+	default: /* case 4: */
+	case 0: return __sindf(y);
+	case 1: return __cosdf(y);
+	case 2: return __sindf(-y);
+	case 3: return -__cosdf(y);
 	}
-	return -y;
 }
 
-
-float lgammaf_r(float x, int *signgamp)
+float __lgammaf_r(float x, int *signgamp)
 {
+	union {float f; uint32_t i;} u = {x};
 	float t,y,z,nadj,p,p1,p2,p3,q,r,w;
-	int32_t hx;
-	int i,ix;
-
-	GET_FLOAT_WORD(hx, x);
+	uint32_t ix;
+	int i,sign;
 
 	/* purge off +-inf, NaN, +-0, tiny and negative arguments */
 	*signgamp = 1;
-	ix = hx & 0x7fffffff;
+	sign = u.i>>31;
+	ix = u.i & 0x7fffffff;
 	if (ix >= 0x7f800000)
 		return x*x;
-	if (ix == 0)
-		return one/zero;
 	if (ix < 0x35000000) {  /* |x| < 2**-21, return -log(|x|) */
-		if (hx < 0) {
+		if (sign) {
 			*signgamp = -1;
-			return -logf(-x);
+			x = -x;
 		}
 		return -logf(x);
 	}
-	if (hx < 0) {
-		if (ix >= 0x4b000000)  /* |x| >= 2**23, must be -integer */
-			return one/zero;
-		t = sin_pif(x);
-		if (t == zero) /* -integer */
-			return one/zero;
-		nadj = logf(pi/fabsf(t*x));
-		if (t < zero)
-			*signgamp = -1;
+	if (sign) {
 		x = -x;
+		t = sin_pi(x);
+		if (t == 0.0f) /* -integer */
+			return 1.0f/(x-x);
+		if (t > 0.0f)
+			*signgamp = -1;
+		else
+			t = -t;
+		nadj = logf(pi/(t*x));
 	}
 
 	/* purge off 1 and 2 */
@@ -176,17 +143,17 @@ float lgammaf_r(float x, int *signgamp)
 		if (ix <= 0x3f666666) {  /* lgamma(x) = lgamma(x+1)-log(x) */
 			r = -logf(x);
 			if (ix >= 0x3f3b4a20) {
-				y = one - x;
+				y = 1.0f - x;
 				i = 0;
 			} else if (ix >= 0x3e6d3308) {
-				y = x - (tc-one);
+				y = x - (tc-1.0f);
 				i = 1;
 			} else {
 				y = x;
 				i = 2;
 			}
 		} else {
-			r = zero;
+			r = 0.0f;
 			if (ix >= 0x3fdda618) {  /* [1.7316,2] */
 				y = 2.0f - x;
 				i = 0;
@@ -194,7 +161,7 @@ float lgammaf_r(float x, int *signgamp)
 				y = x - tc;
 				i = 1;
 			} else {
-				y = x - one;
+				y = x - 1.0f;
 				i = 2;
 			}
 		}
@@ -217,16 +184,16 @@ float lgammaf_r(float x, int *signgamp)
 			break;
 		case 2:
 			p1 = y*(u0+y*(u1+y*(u2+y*(u3+y*(u4+y*u5)))));
-			p2 = one+y*(v1+y*(v2+y*(v3+y*(v4+y*v5))));
+			p2 = 1.0f+y*(v1+y*(v2+y*(v3+y*(v4+y*v5))));
 			r += -0.5f*y + p1/p2;
 		}
 	} else if (ix < 0x41000000) {  /* x < 8.0 */
 		i = (int)x;
 		y = x - (float)i;
 		p = y*(s0+y*(s1+y*(s2+y*(s3+y*(s4+y*(s5+y*s6))))));
-		q = one+y*(r1+y*(r2+y*(r3+y*(r4+y*(r5+y*r6)))));
-		r = half*y+p/q;
-		z = one;    /* lgamma(1+s) = log(s) + lgamma(s) */
+		q = 1.0f+y*(r1+y*(r2+y*(r3+y*(r4+y*(r5+y*r6)))));
+		r = 0.5f*y+p/q;
+		z = 1.0f;    /* lgamma(1+s) = log(s) + lgamma(s) */
 		switch (i) {
 		case 7: z *= y + 6.0f;  /* FALLTHRU */
 		case 6: z *= y + 5.0f;  /* FALLTHRU */
@@ -238,13 +205,15 @@ float lgammaf_r(float x, int *signgamp)
 		}
 	} else if (ix < 0x5c800000) {  /* 8.0 <= x < 2**58 */
 		t = logf(x);
-		z = one/x;
+		z = 1.0f/x;
 		y = z*z;
 		w = w0+z*(w1+y*(w2+y*(w3+y*(w4+y*(w5+y*w6)))));
-		r = (x-half)*(t-one)+w;
+		r = (x-0.5f)*(t-1.0f)+w;
 	} else                         /* 2**58 <= x <= inf */
-		r =  x*(logf(x)-one);
-	if (hx < 0)
+		r =  x*(logf(x)-1.0f);
+	if (sign)
 		r = nadj - r;
 	return r;
 }
+
+weak_alias(__lgammaf_r, lgammaf_r);