Inital import

[l4.git] / l4 / pkg / uclibc / lib / contrib / uclibc / libm / e_hypot.c

diff --git a/l4/pkg/uclibc/lib/contrib/uclibc/libm/e_hypot.c b/l4/pkg/uclibc/lib/contrib/uclibc/libm/e_hypot.c
new file mode 100644 (file)
index 0000000..2649825
--- /dev/null
+++ b/l4/pkg/uclibc/lib/contrib/uclibc/libm/e_hypot.c
@@ -0,0 +1,136 @@
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+/* __ieee754_hypot(x,y)
+ *
+ * Method :
+ *     If (assume round-to-nearest) z=x*x+y*y
+ *     has error less than sqrt(2)/2 ulp, than
+ *     sqrt(z) has error less than 1 ulp (exercise).
+ *
+ *     So, compute sqrt(x*x+y*y) with some care as
+ *     follows to get the error below 1 ulp:
+ *
+ *     Assume x>y>0;
+ *     (if possible, set rounding to round-to-nearest)
+ *     1. if x > 2y  use
+ *             x1*x1+(y*y+(x2*(x+x1))) for x*x+y*y
+ *     where x1 = x with lower 32 bits cleared, x2 = x-x1; else
+ *     2. if x <= 2y use
+ *             t1*y1+((x-y)*(x-y)+(t1*y2+t2*y))
+ *     where t1 = 2x with lower 32 bits cleared, t2 = 2x-t1,
+ *     y1= y with lower 32 bits chopped, y2 = y-y1.
+ *
+ *     NOTE: scaling may be necessary if some argument is too
+ *           large or too tiny
+ *
+ * Special cases:
+ *     hypot(x,y) is INF if x or y is +INF or -INF; else
+ *     hypot(x,y) is NAN if x or y is NAN.
+ *
+ * Accuracy:
+ *     hypot(x,y) returns sqrt(x^2+y^2) with error less
+ *     than 1 ulps (units in the last place)
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+double attribute_hidden __ieee754_hypot(double x, double y)
+{
+       double a=x,b=y,t1,t2,y1,y2,w;
+       int32_t j,k,ha,hb;
+
+       GET_HIGH_WORD(ha,x);
+       ha &= 0x7fffffff;
+       GET_HIGH_WORD(hb,y);
+       hb &= 0x7fffffff;
+       if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
+       SET_HIGH_WORD(a,ha);    /* a <- |a| */
+       SET_HIGH_WORD(b,hb);    /* b <- |b| */
+       if((ha-hb)>0x3c00000) {return a+b;} /* x/y > 2**60 */
+       k=0;
+       if(ha > 0x5f300000) {   /* a>2**500 */
+          if(ha >= 0x7ff00000) {       /* Inf or NaN */
+              u_int32_t low;
+              w = a+b;                 /* for sNaN */
+              GET_LOW_WORD(low,a);
+              if(((ha&0xfffff)|low)==0) w = a;
+              GET_LOW_WORD(low,b);
+              if(((hb^0x7ff00000)|low)==0) w = b;
+              return w;
+          }
+          /* scale a and b by 2**-600 */
+          ha -= 0x25800000; hb -= 0x25800000;  k += 600;
+          SET_HIGH_WORD(a,ha);
+          SET_HIGH_WORD(b,hb);
+       }
+       if(hb < 0x20b00000) {   /* b < 2**-500 */
+           if(hb <= 0x000fffff) {      /* subnormal b or 0 */
+               u_int32_t low;
+               GET_LOW_WORD(low,b);
+               if((hb|low)==0) return a;
+               t1=0;
+               SET_HIGH_WORD(t1,0x7fd00000);   /* t1=2^1022 */
+               b *= t1;
+               a *= t1;
+               k -= 1022;
+           } else {            /* scale a and b by 2^600 */
+               ha += 0x25800000;       /* a *= 2^600 */
+               hb += 0x25800000;       /* b *= 2^600 */
+               k -= 600;
+               SET_HIGH_WORD(a,ha);
+               SET_HIGH_WORD(b,hb);
+           }
+       }
+    /* medium size a and b */
+       w = a-b;
+       if (w>b) {
+           t1 = 0;
+           SET_HIGH_WORD(t1,ha);
+           t2 = a-t1;
+           w  = __ieee754_sqrt(t1*t1-(b*(-b)-t2*(a+t1)));
+       } else {
+           a  = a+a;
+           y1 = 0;
+           SET_HIGH_WORD(y1,hb);
+           y2 = b - y1;
+           t1 = 0;
+           SET_HIGH_WORD(t1,ha+0x00100000);
+           t2 = a - t1;
+           w  = __ieee754_sqrt(t1*y1-(w*(-w)-(t1*y2+t2*b)));
+       }
+       if(k!=0) {
+           u_int32_t high;
+           t1 = 1.0;
+           GET_HIGH_WORD(high,t1);
+           SET_HIGH_WORD(t1,high+(k<<20));
+           return t1*w;
+       } else return w;
+}
+
+/*
+ * wrapper hypot(x,y)
+ */
+#ifndef _IEEE_LIBM
+double hypot(double x, double y)
+{
+       double z = __ieee754_hypot(x, y);
+       if (_LIB_VERSION == _IEEE_)
+               return z;
+       if ((!isfinite(z)) && isfinite(x) && isfinite(y))
+               return __kernel_standard(x, y, 4); /* hypot overflow */
+       return z;
+}
+#else
+strong_alias(__ieee754_hypot, hypot)
+#endif
+libm_hidden_def(hypot)