frexp: replace MUSL with Sun version for portability

diff --git a/Library/libs/frexp.c b/Library/libs/frexp.c
index 509e92f..4023ce4 100644 (file)
--- a/Library/libs/frexp.c
+++ b/Library/libs/frexp.c
@@ -1,25 +1,47 @@
-/* From MUSL */
-
 #include <math.h>
-#include <stdint.h>
+#include "libm.h"
 
-double frexp(double x, int *e)
-{
-       union { double d; uint64_t i; } y = { x };
-       int ee = y.i>>52 & 0x7ff;
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
 
-       if (!ee) {
-               if (x) {
-                       x = frexp(x*0x1p64, e);
-                       *e -= 64;
-               } else *e = 0;
-               return x;
-       } else if (ee == 0x7ff) {
-               return x;
-       }
 
-       *e = ee - 0x3fe;
-       y.i &= 0x800fffffffffffffull;
-       y.i |= 0x3fe0000000000000ull;
-       return y.d;
+/*
+ * for non-zero x
+ *     x = frexp(arg,&exp);
+ * return a double fp quantity x such that 0.5 <= |x| <1.0
+ * and the corresponding binary exponent "exp". That is
+ *     arg = x*2^exp.
+ * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
+ * with *exp=0.
+ */
+
+static const double
+two54 =  1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */
+
+double
+frexp(double x, int *eptr)
+{
+       int32_t hx, ix, lx;
+       EXTRACT_WORDS(hx,lx,x);
+       ix = 0x7fffffff&hx;
+       *eptr = 0;
+       if(ix>=0x7ff00000||((ix|lx)==0)) return x;      /* 0,inf,nan */
+       if (ix<0x00100000) {            /* subnormal */
+           x *= two54;
+           GET_HIGH_WORD(hx,x);
+           ix = hx&0x7fffffff;
+           *eptr = -54;
+       }
+       *eptr += (ix>>20)-1022;
+       hx = (hx&0x800fffff)|0x3fe00000;
+       SET_HIGH_WORD(x,hx);
+       return x;
 }