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/* @(#)s_nextafter.c 5.1 93/09/24 */ |
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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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/* IEEE functions |
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* nexttowardf(x,y) |
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* return the next machine floating-point number of x in the |
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* direction toward y. |
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* This is for machines which use the same binary type for double and |
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* long double. |
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* Special cases: |
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*/ |
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#include <math.h> |
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#include <float.h> |
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#include "math_private.h" |
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float |
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nexttowardf(float x, long double y) |
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{ |
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int32_t hx,hy,ix,iy; |
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u_int32_t ly; |
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GET_FLOAT_WORD(hx,x); |
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EXTRACT_WORDS(hy,ly,y); |
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ix = hx&0x7fffffff; /* |x| */ |
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iy = hy&0x7fffffff; /* |y| */ |
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if((ix>0x7f800000) || /* x is nan */ |
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((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */ |
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return x+y; |
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if((long double) x==y) return y; /* x=y, return y */ |
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if(ix==0) { /* x == 0 */ |
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volatile float u; |
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SET_FLOAT_WORD(x,(u_int32_t)(hy&0x80000000)|1);/* return +-minsub*/ |
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u = x; |
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u = u * u; /* raise underflow flag */ |
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return x; |
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} |
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if(hx>=0) { /* x > 0 */ |
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if(hy<0||(ix>>23)>(iy>>20)-0x380 |
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|| ((ix>>23)==(iy>>20)-0x380 |
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&& (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff))) /* x > y, x -= ulp */ |
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hx -= 1; |
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else /* x < y, x += ulp */ |
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hx += 1; |
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} else { /* x < 0 */ |
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if(hy>=0||(ix>>23)>(iy>>20)-0x380 |
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|| ((ix>>23)==(iy>>20)-0x380 |
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&& (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff))) /* x < y, x -= ulp */ |
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hx -= 1; |
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else /* x > y, x += ulp */ |
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hx += 1; |
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} |
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hy = hx&0x7f800000; |
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if(hy>=0x7f800000) { |
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x = x+x; /* overflow */ |
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return x; |
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} |
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if(hy<0x00800000) { |
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volatile float u = x*x; /* underflow */ |
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if(u==x) { |
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SET_FLOAT_WORD(x,hx); |
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return x; |
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} |
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} |
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SET_FLOAT_WORD(x,hx); |
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return x; |
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} |