X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fmath%2F__rem_pio2f.c;h=e67656431a825480c779fd08ab0735f1a6a63572;hb=0a7b4323b0f2b944dbd47a813c0c6e6813e7fd67;hp=965dc46ac53a01b0a5dc05b4a2d82efda6f23ad5;hpb=b69f695acedd4ce2798ef9ea28d834ceccc789bd;p=musl

diff --git a/src/math/__rem_pio2f.c b/src/math/__rem_pio2f.c
index 965dc46a..e6765643 100644
--- a/src/math/__rem_pio2f.c
+++ b/src/math/__rem_pio2f.c
@@ -22,54 +22,62 @@
 
 #include "libm.h"
 
+#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1
+#define EPS DBL_EPSILON
+#elif FLT_EVAL_METHOD==2
+#define EPS LDBL_EPSILON
+#endif
+
 /*
  * invpio2:  53 bits of 2/pi
- * pio2_1:   first  33 bit of pi/2
+ * pio2_1:   first 25 bits of pi/2
  * pio2_1t:  pi/2 - pio2_1
  */
 static const double
+toint   = 1.5/EPS,
+pio4    = 0x1.921fb6p-1,
 invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
 pio2_1  = 1.57079631090164184570e+00, /* 0x3FF921FB, 0x50000000 */
 pio2_1t = 1.58932547735281966916e-08; /* 0x3E5110b4, 0x611A6263 */
 
 int __rem_pio2f(float x, double *y)
 {
-	double w,r,fn;
+	union {float f; uint32_t i;} u = {x};
 	double tx[1],ty[1];
-	float z;
-	int32_t e0,n,ix,hx;
+	double_t fn;
+	uint32_t ix;
+	int n, sign, e0;
 
-	GET_FLOAT_WORD(hx, x);
-	ix = hx & 0x7fffffff;
-	/* 33+53 bit pi is good enough for medium size */
+	ix = u.i & 0x7fffffff;
+	/* 25+53 bit pi is good enough for medium size */
 	if (ix < 0x4dc90fdb) {  /* |x| ~< 2^28*(pi/2), medium size */
-		/* Use a specialized rint() to get fn.  Assume round-to-nearest. */
-		STRICT_ASSIGN(double, fn, x*invpio2 + 0x1.8p52);
-		fn = fn - 0x1.8p52;
-// FIXME
-#ifdef HAVE_EFFICIENT_IRINT
-		n  = irint(fn);
-#else
+		/* Use a specialized rint() to get fn. */
+		fn = (double_t)x*invpio2 + toint - toint;
 		n  = (int32_t)fn;
-#endif
-		r  = x - fn*pio2_1;
-		w  = fn*pio2_1t;
-		*y = r - w;
+		*y = x - fn*pio2_1 - fn*pio2_1t;
+		/* Matters with directed rounding. */
+		if (predict_false(*y < -pio4)) {
+			n--;
+			fn--;
+			*y = x - fn*pio2_1 - fn*pio2_1t;
+		} else if (predict_false(*y > pio4)) {
+			n++;
+			fn++;
+			*y = x - fn*pio2_1 - fn*pio2_1t;
+		}
 		return n;
 	}
-	/*
-	 * all other (large) arguments
-	 */
 	if(ix>=0x7f800000) {  /* x is inf or NaN */
 		*y = x-x;
 		return 0;
 	}
-	/* set z = scalbn(|x|,ilogb(|x|)-23) */
-	e0 = (ix>>23) - 150;  /* e0 = ilogb(|x|)-23; */
-	SET_FLOAT_WORD(z, ix - ((int32_t)(e0<<23)));
-	tx[0] = z;
+	/* scale x into [2^23, 2^24-1] */
+	sign = u.i>>31;
+	e0 = (ix>>23) - (0x7f+23);  /* e0 = ilogb(|x|)-23, positive */
+	u.i = ix - (e0<<23);
+	tx[0] = u.f;
 	n  =  __rem_pio2_large(tx,ty,e0,1,0);
-	if (hx < 0) {
+	if (sign) {
 		*y = -ty[0];
 		return -n;
 	}