| 1 | /* s_nextafterf.c -- float version of s_nextafter.c.
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| 2 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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| 3 | */
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| 4 |
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| 5 | /*
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| 6 | * ====================================================
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| 7 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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| 8 | *
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| 9 | * Developed at SunPro, a Sun Microsystems, Inc. business.
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| 10 | * Permission to use, copy, modify, and distribute this
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| 11 | * software is freely granted, provided that this notice
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| 12 | * is preserved.
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| 13 | * ====================================================
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| 14 | */
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| 15 |
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| 16 | #ifndef lint
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| 17 | static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_nextafterf.c,v 1.10 2005/03/07 04:55:58 das Exp $";
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| 18 | #endif
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| 19 |
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| 20 | #include "math.h"
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| 21 | #include "math_private.h"
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| 22 |
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| 23 | float
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| 24 | nextafterf(float x, float y)
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| 25 | {
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| 26 | volatile float t;
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| 27 | int32_t hx,hy,ix,iy;
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| 28 |
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| 29 | GET_FLOAT_WORD(hx,x);
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| 30 | GET_FLOAT_WORD(hy,y);
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| 31 | ix = hx&0x7fffffff; /* |x| */
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| 32 | iy = hy&0x7fffffff; /* |y| */
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| 33 |
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| 34 | if((ix>0x7f800000) || /* x is nan */
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| 35 | (iy>0x7f800000)) /* y is nan */
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| 36 | return x+y;
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| 37 | if(x==y) return y; /* x=y, return y */
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| 38 | if(ix==0) { /* x == 0 */
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| 39 | SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
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| 40 | t = x*x;
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| 41 | if(t==x) return t; else return x; /* raise underflow flag */
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| 42 | }
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| 43 | if(hx>=0) { /* x > 0 */
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| 44 | if(hx>hy) { /* x > y, x -= ulp */
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| 45 | hx -= 1;
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| 46 | } else { /* x < y, x += ulp */
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| 47 | hx += 1;
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| 48 | }
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| 49 | } else { /* x < 0 */
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| 50 | if(hy>=0||hx>hy){ /* x < y, x -= ulp */
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| 51 | hx -= 1;
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| 52 | } else { /* x > y, x += ulp */
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| 53 | hx += 1;
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| 54 | }
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| 55 | }
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| 56 | hy = hx&0x7f800000;
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| 57 | if(hy>=0x7f800000) return x+x; /* overflow */
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| 58 | if(hy<0x00800000) { /* underflow */
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| 59 | t = x*x;
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| 60 | if(t!=x) { /* raise underflow flag */
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| 61 | SET_FLOAT_WORD(y,hx);
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| 62 | return y;
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| 63 | }
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| 64 | }
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| 65 | SET_FLOAT_WORD(x,hx);
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| 66 | return x;
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| 67 | }
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