/*
 * ====================================================
 * 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 e_hypot.c for most comments. */

#include <float.h>

#include "fpmath.h"
#include "math.h"
#include "math_private.h"

#define GET_LDBL_MAN(h, l, v) do {      \
        union IEEEl2bits uv;            \
                                        \
        uv.e = v;                       \
        h = uv.bits.manh;               \
        l = uv.bits.manl;               \
} 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)) {return a+b;} /* x/y > 2**(MANT_DIG+7) */
        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+0.0L)-fabsl(y+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=1;
                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) {
            u_int32_t high;
            t1 = 1.0;
            GET_HIGH_WORD(high,t1);
            SET_HIGH_WORD(t1,high+DESW(k));
            return t1*w;
        } else return w;
}