s_nexttowardf.c revision 143218
1143218Sdas/* 2143218Sdas * ==================================================== 3143218Sdas * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 4143218Sdas * 5143218Sdas * Developed at SunPro, a Sun Microsystems, Inc. business. 6143218Sdas * Permission to use, copy, modify, and distribute this 7143218Sdas * software is freely granted, provided that this notice 8143218Sdas * is preserved. 9143218Sdas * ==================================================== 10143218Sdas */ 11143218Sdas 12143218Sdas#ifndef lint 13143218Sdasstatic char rcsid[] = "$FreeBSD: head/lib/msun/src/s_nexttowardf.c 143218 2005-03-07 04:57:38Z das $"; 14143218Sdas#endif 15143218Sdas 16143218Sdas#include <float.h> 17143218Sdas 18143218Sdas#include "fpmath.h" 19143218Sdas#include "math.h" 20143218Sdas#include "math_private.h" 21143218Sdas 22143218Sdas#define LDBL_INFNAN_EXP (LDBL_MAX_EXP * 2 - 1) 23143218Sdas 24143218Sdasfloat 25143218Sdasnexttowardf(float x, long double y) 26143218Sdas{ 27143218Sdas union IEEEl2bits uy; 28143218Sdas volatile float t; 29143218Sdas int32_t hx,ix; 30143218Sdas 31143218Sdas GET_FLOAT_WORD(hx,x); 32143218Sdas ix = hx&0x7fffffff; /* |x| */ 33143218Sdas uy.e = y; 34143218Sdas 35143218Sdas if((ix>0x7f800000) || 36143218Sdas (uy.bits.exp == LDBL_INFNAN_EXP && 37143218Sdas ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0)) 38143218Sdas return x+y; /* x or y is nan */ 39143218Sdas if(x==y) return (float)y; /* x=y, return y */ 40143218Sdas if(ix==0) { /* x == 0 */ 41143218Sdas SET_FLOAT_WORD(x,(uy.bits.sign<<31)|1);/* return +-minsubnormal */ 42143218Sdas t = x*x; 43143218Sdas if(t==x) return t; else return x; /* raise underflow flag */ 44143218Sdas } 45143218Sdas if(hx>=0 ^ x < y) /* x -= ulp */ 46143218Sdas hx -= 1; 47143218Sdas else /* x += ulp */ 48143218Sdas hx += 1; 49143218Sdas ix = hx&0x7f800000; 50143218Sdas if(ix>=0x7f800000) return x+x; /* overflow */ 51143218Sdas if(ix<0x00800000) { /* underflow */ 52143218Sdas t = x*x; 53143218Sdas if(t!=x) { /* raise underflow flag */ 54143218Sdas SET_FLOAT_WORD(y,hx); 55143218Sdas return y; 56143218Sdas } 57143218Sdas } 58143218Sdas SET_FLOAT_WORD(x,hx); 59143218Sdas return x; 60143218Sdas} 61