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145 lines
4.0 KiB
C
145 lines
4.0 KiB
C
/*
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* IBM Accurate Mathematical Library
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* Written by International Business Machines Corp.
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* Copyright (C) 2001-2020 Free Software Foundation, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses/>.
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*/
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/*******************************************************************/
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/* */
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/* MODULE_NAME: branred.c */
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/* */
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/* FUNCTIONS: branred */
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/* */
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/* FILES NEEDED: branred.h mydefs.h endian.h mpa.h */
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/* mha.c */
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/* */
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/* Routine branred() performs range reduction of a double number */
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/* x into Double length number a+aa,such that */
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/* x=n*pi/2+(a+aa), abs(a+aa)<pi/4, n=0,+-1,+-2,.... */
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/* Routine returns the integer (n mod 4) of the above description */
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/* of x. */
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/*******************************************************************/
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#include "endian.h"
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#include "mydefs.h"
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#include "branred.h"
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#include <math.h>
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#include <math_private.h>
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#ifndef SECTION
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# define SECTION
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#endif
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/*******************************************************************/
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/* Routine branred() performs range reduction of a double number */
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/* x into Double length number a+aa,such that */
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/* x=n*pi/2+(a+aa), abs(a+aa)<pi/4, n=0,+-1,+-2,.... */
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/* Routine return integer (n mod 4) */
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/*******************************************************************/
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int
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SECTION
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__branred(double x, double *a, double *aa)
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{
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int i,k;
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mynumber u,gor;
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double r[6],s,t,sum,b,bb,sum1,sum2,b1,bb1,b2,bb2,x1,x2,t1,t2;
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x*=tm600.x;
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t=x*split; /* split x to two numbers */
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x1=t-(t-x);
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x2=x-x1;
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sum=0;
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u.x = x1;
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k = (u.i[HIGH_HALF]>>20)&2047;
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k = (k-450)/24;
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if (k<0)
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k=0;
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gor.x = t576.x;
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gor.i[HIGH_HALF] -= ((k*24)<<20);
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for (i=0;i<6;i++)
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{ r[i] = x1*toverp[k+i]*gor.x; gor.x *= tm24.x; }
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for (i=0;i<3;i++) {
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s=(r[i]+big.x)-big.x;
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sum+=s;
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r[i]-=s;
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}
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t=0;
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for (i=0;i<6;i++)
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t+=r[5-i];
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bb=(((((r[0]-t)+r[1])+r[2])+r[3])+r[4])+r[5];
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s=(t+big.x)-big.x;
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sum+=s;
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t-=s;
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b=t+bb;
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bb=(t-b)+bb;
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s=(sum+big1.x)-big1.x;
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sum-=s;
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b1=b;
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bb1=bb;
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sum1=sum;
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sum=0;
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u.x = x2;
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k = (u.i[HIGH_HALF]>>20)&2047;
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k = (k-450)/24;
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if (k<0)
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k=0;
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gor.x = t576.x;
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gor.i[HIGH_HALF] -= ((k*24)<<20);
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for (i=0;i<6;i++)
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{ r[i] = x2*toverp[k+i]*gor.x; gor.x *= tm24.x; }
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for (i=0;i<3;i++) {
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s=(r[i]+big.x)-big.x;
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sum+=s;
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r[i]-=s;
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}
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t=0;
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for (i=0;i<6;i++)
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t+=r[5-i];
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bb=(((((r[0]-t)+r[1])+r[2])+r[3])+r[4])+r[5];
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s=(t+big.x)-big.x;
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sum+=s;
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t-=s;
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b=t+bb;
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bb=(t-b)+bb;
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s=(sum+big1.x)-big1.x;
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sum-=s;
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b2=b;
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bb2=bb;
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sum2=sum;
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sum=sum1+sum2;
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b=b1+b2;
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bb = (fabs(b1)>fabs(b2))? (b1-b)+b2 : (b2-b)+b1;
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if (b > 0.5)
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{b-=1.0; sum+=1.0;}
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else if (b < -0.5)
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{b+=1.0; sum-=1.0;}
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s=b+(bb+bb1+bb2);
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t=((b-s)+bb)+(bb1+bb2);
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b=s*split;
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t1=b-(b-s);
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t2=s-t1;
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b=s*hp0.x;
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bb=(((t1*mp1.x-b)+t1*mp2.x)+t2*mp1.x)+(t2*mp2.x+s*hp1.x+t*hp0.x);
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s=b+bb;
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t=(b-s)+bb;
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*a=s;
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*aa=t;
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return ((int) sum)&3; /* return quater of unit circle */
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}
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