125 lines
3.2 KiB
C
125 lines
3.2 KiB
C
/* From: @(#)e_hypot.c 1.3 95/01/18 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/* long double version of hypot(). See e_hypot.c for most comments. */
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#include <float.h>
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#include "fpmath.h"
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#include "math.h"
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#include "math_private.h"
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#define GET_LDBL_MAN(h, l, v) do { \
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union IEEEl2bits uv; \
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\
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uv.e = v; \
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h = uv.bits.manh; \
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l = uv.bits.manl; \
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} while (0)
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#undef GET_HIGH_WORD
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#define GET_HIGH_WORD(i, v) GET_LDBL_EXPSIGN(i, v)
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#undef SET_HIGH_WORD
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#define SET_HIGH_WORD(v, i) SET_LDBL_EXPSIGN(v, i)
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#define DESW(exp) (exp) /* delta expsign word */
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#define ESW(exp) (MAX_EXP - 1 + (exp)) /* expsign word */
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#define MANT_DIG LDBL_MANT_DIG
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#define MAX_EXP LDBL_MAX_EXP
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#if LDBL_MANL_SIZE > 32
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typedef uint64_t man_t;
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#else
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typedef uint32_t man_t;
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#endif
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long double
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hypotl(long double x, long double y)
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{
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long double a=x,b=y,t1,t2,y1,y2,w;
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int32_t j,k,ha,hb;
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GET_HIGH_WORD(ha,x);
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ha &= 0x7fff;
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GET_HIGH_WORD(hb,y);
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hb &= 0x7fff;
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if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
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a = fabsl(a);
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b = fabsl(b);
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if((ha-hb)>DESW(MANT_DIG+7)) {return a+b;} /* x/y > 2**(MANT_DIG+7) */
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k=0;
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if(ha > ESW(MAX_EXP/2-12)) { /* a>2**(MAX_EXP/2-12) */
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if(ha >= ESW(MAX_EXP)) { /* Inf or NaN */
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man_t manh, manl;
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/* Use original arg order iff result is NaN; quieten sNaNs. */
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w = fabsl(x+0.0)-fabsl(y+0.0);
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GET_LDBL_MAN(manh,manl,a);
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if (manh == LDBL_NBIT && manl == 0) w = a;
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GET_LDBL_MAN(manh,manl,b);
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if (hb >= ESW(MAX_EXP) && manh == LDBL_NBIT && manl == 0) w = b;
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return w;
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}
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/* scale a and b by 2**-(MAX_EXP/2+88) */
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ha -= DESW(MAX_EXP/2+88); hb -= DESW(MAX_EXP/2+88);
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k += MAX_EXP/2+88;
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SET_HIGH_WORD(a,ha);
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SET_HIGH_WORD(b,hb);
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}
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if(hb < ESW(-(MAX_EXP/2-12))) { /* b < 2**-(MAX_EXP/2-12) */
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if(hb <= 0) { /* subnormal b or 0 */
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man_t manh, manl;
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GET_LDBL_MAN(manh,manl,b);
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if((manh|manl)==0) return a;
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t1=0;
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SET_HIGH_WORD(t1,ESW(MAX_EXP-2)); /* t1=2^(MAX_EXP-2) */
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b *= t1;
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a *= t1;
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k -= MAX_EXP-2;
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} else { /* scale a and b by 2^(MAX_EXP/2+88) */
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ha += DESW(MAX_EXP/2+88);
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hb += DESW(MAX_EXP/2+88);
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k -= MAX_EXP/2+88;
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SET_HIGH_WORD(a,ha);
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SET_HIGH_WORD(b,hb);
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}
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}
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/* medium size a and b */
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w = a-b;
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if (w>b) {
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t1 = a;
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union IEEEl2bits uv;
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uv.e = t1; uv.bits.manl = 0; t1 = uv.e;
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t2 = a-t1;
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w = sqrtl(t1*t1-(b*(-b)-t2*(a+t1)));
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} else {
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a = a+a;
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y1 = b;
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union IEEEl2bits uv;
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uv.e = y1; uv.bits.manl = 0; y1 = uv.e;
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y2 = b - y1;
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t1 = a;
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uv.e = t1; uv.bits.manl = 0; t1 = uv.e;
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t2 = a - t1;
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w = sqrtl(t1*y1-(w*(-w)-(t1*y2+t2*b)));
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}
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if(k!=0) {
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u_int32_t high;
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t1 = 1.0;
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GET_HIGH_WORD(high,t1);
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SET_HIGH_WORD(t1,high+DESW(k));
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return t1*w;
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} else return w;
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}
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