first commit of the new libm!

[musl] / src / math / hypotl.c

diff --git a/src/math/hypotl.c b/src/math/hypotl.c
new file mode 100644 (file)
index 0000000..f4a64f7
--- /dev/null
+++ b/src/math/hypotl.c
@@ -0,0 +1,148 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/e_hypotl.c */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+/* long double version of hypot().  See comments in hypot.c. */
+
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double hypotl(long double x, long double y)
+{
+       return hypot(x, y);
+}
+#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+
+#define GET_LDBL_EXPSIGN(i, v) do {     \
+       union IEEEl2bits uv;            \
+                                       \
+       uv.e = v;                       \
+       i = uv.xbits.expsign;           \
+} while (0)
+
+#define GET_LDBL_MAN(h, l, v) do {      \
+       union IEEEl2bits uv;            \
+                                       \
+       uv.e = v;                       \
+       h = uv.bits.manh;               \
+       l = uv.bits.manl;               \
+} while (0)
+
+#define SET_LDBL_EXPSIGN(v, i) do {     \
+       union IEEEl2bits uv;            \
+                                       \
+       uv.e = v;                       \
+       uv.xbits.expsign = i;           \
+       v = uv.e;                       \
+} while (0)
+
+#undef GET_HIGH_WORD
+#define GET_HIGH_WORD(i, v)     GET_LDBL_EXPSIGN(i, v)
+#undef SET_HIGH_WORD
+#define SET_HIGH_WORD(v, i)     SET_LDBL_EXPSIGN(v, i)
+
+#define DESW(exp)       (exp)           /* delta expsign word */
+#define ESW(exp)        (MAX_EXP - 1 + (exp))   /* expsign word */
+#define MANT_DIG        LDBL_MANT_DIG
+#define MAX_EXP         LDBL_MAX_EXP
+
+#if LDBL_MANL_SIZE > 32
+typedef uint64_t man_t;
+#else
+typedef uint32_t man_t;
+#endif
+
+long double hypotl(long double x, long double y)
+{
+       long double a=x,b=y,t1,t2,y1,y2,w;
+       int32_t j,k,ha,hb;
+
+       GET_HIGH_WORD(ha, x);
+       ha &= 0x7fff;
+       GET_HIGH_WORD(hb, y);
+       hb &= 0x7fff;
+       if (hb > ha) {
+               a = y;
+               b = x;
+               j=ha; ha=hb; hb=j;
+       } else {
+               a = x;
+               b = y;
+       }
+       a = fabsl(a);
+       b = fabsl(b);
+       if (ha - hb > DESW(MANT_DIG+7))  /* x/y > 2**(MANT_DIG+7) */
+               return a+b;
+       k = 0;
+       if (ha > ESW(MAX_EXP/2-12)) {    /* a>2**(MAX_EXP/2-12) */
+               if (ha >= ESW(MAX_EXP)) {  /* Inf or NaN */
+                       man_t manh, manl;
+                       /* Use original arg order iff result is NaN; quieten sNaNs. */
+                       w = fabsl(x+0.0)-fabsl(y+0.0);
+                       GET_LDBL_MAN(manh,manl,a);
+                       if (manh == LDBL_NBIT && manl == 0) w = a;
+                       GET_LDBL_MAN(manh,manl,b);
+                       if (hb >= ESW(MAX_EXP) && manh == LDBL_NBIT && manl == 0) w = b;
+                       return w;
+               }
+               /* scale a and b by 2**-(MAX_EXP/2+88) */
+               ha -= DESW(MAX_EXP/2+88); hb -= DESW(MAX_EXP/2+88);
+               k += MAX_EXP/2+88;
+               SET_HIGH_WORD(a, ha);
+               SET_HIGH_WORD(b, hb);
+       }
+       if (hb < ESW(-(MAX_EXP/2-12))) {  /* b < 2**-(MAX_EXP/2-12) */
+               if (hb <= 0) {  /* subnormal b or 0 */
+                       man_t manh, manl;
+                       GET_LDBL_MAN(manh,manl,b);
+                       if ((manh|manl) == 0)
+                               return a;
+                       t1 = 0;
+                       SET_HIGH_WORD(t1, ESW(MAX_EXP-2));  /* t1 = 2^(MAX_EXP-2) */
+                       b *= t1;
+                       a *= t1;
+                       k -= MAX_EXP-2;
+               } else {            /* scale a and b by 2^(MAX_EXP/2+88) */
+                       ha += DESW(MAX_EXP/2+88);
+                       hb += DESW(MAX_EXP/2+88);
+                       k -= MAX_EXP/2+88;
+                       SET_HIGH_WORD(a, ha);
+                       SET_HIGH_WORD(b, hb);
+               }
+       }
+       /* medium size a and b */
+       w = a - b;
+       if (w > b) {
+               t1 = a;
+               union IEEEl2bits uv;
+               uv.e = t1; uv.bits.manl = 0; t1 = uv.e;
+               t2 = a-t1;
+               w  = sqrtl(t1*t1-(b*(-b)-t2*(a+t1)));
+       } else {
+               a  = a+a;
+               y1 = b;
+               union IEEEl2bits uv;
+               uv.e = y1; uv.bits.manl = 0; y1 = uv.e;
+               y2 = b - y1;
+               t1 = a;
+               uv.e = t1; uv.bits.manl = 0; t1 = uv.e;
+               t2 = a - t1;
+               w  = sqrtl(t1*y1-(w*(-w)-(t1*y2+t2*b)));
+       }
+       if(k!=0) {
+               uint32_t high;
+               t1 = 1.0;
+               GET_HIGH_WORD(high, t1);
+               SET_HIGH_WORD(t1, high+DESW(k));
+               return t1*w;
+       }
+       return w;
+}
+#endif