5980be9b3c
This work is based in part on code from NetBSD libm, libc and kernel. The library is partly public domain and partly BSD-style licensed.
69 lines
1.6 KiB
C
69 lines
1.6 KiB
C
/* s_rintf.c -- float version of s_rint.c.
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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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 SunPro, 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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#if defined(LIBM_SCCS) && !defined(lint)
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__RCSID("$NetBSD: s_rintf.c,v 1.9 2008/04/25 22:21:53 christos Exp $");
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#endif
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#include "math.h"
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#include "math_private.h"
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static const float
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TWO23[2]={
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8.3886080000e+06, /* 0x4b000000 */
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-8.3886080000e+06, /* 0xcb000000 */
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};
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float
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rintf(float x)
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{
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int32_t i0,jj0,sx;
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uint32_t i,i1;
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#ifdef __i386__ /* XXX gcc4 will omit the rounding otherwise */
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volatile
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#endif
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float w;
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float t;
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GET_FLOAT_WORD(i0,x);
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sx = (i0>>31)&1;
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jj0 = ((i0>>23)&0xff)-0x7f;
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if(jj0<23) {
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if(jj0<0) {
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if((i0&0x7fffffff)==0) return x;
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i1 = (i0&0x07fffff);
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i0 &= 0xfff00000;
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i0 |= ((i1|-i1)>>9)&0x400000;
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SET_FLOAT_WORD(x,i0);
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w = TWO23[sx]+x;
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t = w-TWO23[sx];
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GET_FLOAT_WORD(i0,t);
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SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
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return t;
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} else {
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i = (0x007fffff)>>jj0;
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if((i0&i)==0) return x; /* x is integral */
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i>>=1;
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if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>jj0);
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}
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} else {
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if(jj0==0x80) return x+x; /* inf or NaN */
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else return x; /* x is integral */
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}
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SET_FLOAT_WORD(x,i0);
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w = TWO23[sx]+x;
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return w-TWO23[sx];
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}
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