1  /* s_nextafterf.c -- float version of s_nextafter.c.
       2   */
       3  
       4  /*
       5   * ====================================================
       6   * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
       7   *
       8   * Developed at SunPro, a Sun Microsystems, Inc. business.
       9   * Permission to use, copy, modify, and distribute this
      10   * software is freely granted, provided that this notice
      11   * is preserved.
      12   * ====================================================
      13   */
      14  
      15  #if defined(LIBM_SCCS) && !defined(lint)
      16  static char rcsid[] = "$NetBSD: s_nextafterf.c,v 1.4 1995/05/10 20:48:01 jtc Exp $";
      17  #endif
      18  
      19  #include <errno.h>
      20  #include <math.h>
      21  #include <math-barriers.h>
      22  #include <math_private.h>
      23  #include <libm-alias-float.h>
      24  #include <float.h>
      25  
      26  float __nextafterf(float x, float y)
      27  {
      28  	int32_t hx,hy,ix,iy;
      29  
      30  	GET_FLOAT_WORD(hx,x);
      31  	GET_FLOAT_WORD(hy,y);
      32  	ix = hx&0x7fffffff;		/* |x| */
      33  	iy = hy&0x7fffffff;		/* |y| */
      34  
      35  	if((ix>0x7f800000) ||   /* x is nan */
      36  	   (iy>0x7f800000))     /* y is nan */
      37  	   return x+y;
      38  	if(x==y) return y;		/* x=y, return y */
      39  	if(ix==0) {				/* x == 0 */
      40  	    float u;
      41  	    SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
      42  	    u = math_opt_barrier (x);
      43  	    u = u*u;
      44  	    math_force_eval (u);		/* raise underflow flag */
      45  	    return x;
      46  	}
      47  	if(hx>=0) {				/* x > 0 */
      48  	    if(hx>hy) {				/* x > y, x -= ulp */
      49  		hx -= 1;
      50  	    } else {				/* x < y, x += ulp */
      51  		hx += 1;
      52  	    }
      53  	} else {				/* x < 0 */
      54  	    if(hy>=0||hx>hy){			/* x < y, x -= ulp */
      55  		hx -= 1;
      56  	    } else {				/* x > y, x += ulp */
      57  		hx += 1;
      58  	    }
      59  	}
      60  	hy = hx&0x7f800000;
      61  	if(hy>=0x7f800000) {
      62  	  float u = x+x;	/* overflow  */
      63  	  math_force_eval (u);
      64  	  __set_errno (ERANGE);
      65  	}
      66  	if(hy<0x00800000) {
      67  	    float u = x*x;			/* underflow */
      68  	    math_force_eval (u);		/* raise underflow flag */
      69  	    __set_errno (ERANGE);
      70  	}
      71  	SET_FLOAT_WORD(x,hx);
      72  	return x;
      73  }
      74  libm_alias_float (__nextafter, nextafter)