sysdeps/ieee754/ldbl-opt/s_nexttowardfd.c

   1 /* Single precision version of nexttoward.c.
   2    Conversion to IEEE single float by Jakub Jelinek, jj@ultra.linux.cz. */
   3 /*
   4  * ====================================================
   5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   6  *
   7  * Developed at SunPro, a Sun Microsystems, Inc. business.
   8  * Permission to use, copy, modify, and distribute this
   9  * software is freely granted, provided that this notice
  10  * is preserved.
  11  * ====================================================
  12  */
  13
  14 /* IEEE functions
  15  *      __nexttowardfd(x,y)
  16  *      return the next machine floating-point number of x in the
  17  *      direction toward y.
  18  * This is for machines which use different binary type for double and
  19  * long double conditionally, y is long double equal to double.
  20  *   Special cases:
  21  */
  22
  23 #include <math_ldbl_opt.h>
  24
  25 float __nldbl_nexttowardf(float x, double y);
  26
  27 float __nldbl_nexttowardf(float x, double y)
  28 {
  29         int32_t hx,hy,ix,iy;
  30         u_int32_t ly;
  31
  32         GET_FLOAT_WORD(hx,x);
  33         EXTRACT_WORDS(hy,ly,y);
  34         ix = hx&0x7fffffff;             /* |x| */
  35         iy = hy&0x7fffffff;             /* |y| */
  36
  37         if((ix>0x7f800000) ||                              /* x is nan */
  38            ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))    /* y is nan */
  39            return x+y;
  40         if((double) x==y) return y;             /* x=y, return y */
  41         if(ix==0) {                             /* x == 0 */
  42             float x2;
  43             SET_FLOAT_WORD(x,(u_int32_t)(hy&0x80000000)|1);/* return +-minsub*/
  44             x2 = x*x;
  45             if(x2==x) return x2; else return x; /* raise underflow flag */
  46         }
  47         if(hx>=0) {                             /* x > 0 */
  48             if(hy<0||(ix>>23)>(iy>>20)-0x380
  49                || ((ix>>23)==(iy>>20)-0x380
  50                    && (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff)))     /* x > y, x -= ulp */
  51                 hx -= 1;
  52             else                                /* x < y, x += ulp */
  53                 hx += 1;
  54         } else {                                /* x < 0 */
  55             if(hy>=0||(ix>>23)>(iy>>20)-0x380
  56                || ((ix>>23)==(iy>>20)-0x380
  57                    && (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff)))     /* x < y, x -= ulp */
  58                 hx -= 1;
  59             else                                /* x > y, x += ulp */
  60                 hx += 1;
  61         }
  62         hy = hx&0x7f800000;
  63         if(hy>=0x7f800000) return x+x;  /* overflow  */
  64         if(hy<0x00800000) {             /* underflow */
  65             float x2 = x*x;
  66             if(x2!=x) {         /* raise underflow flag */
  67                 SET_FLOAT_WORD(x2,hx);
  68                 return x2;
  69             }
  70         }
  71         SET_FLOAT_WORD(x,hx);
  72         return x;
  73 }
  74
  75 #if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
  76 compat_symbol (libm, __nldbl_nexttowardf, nexttowardf, GLIBC_2_1);
  77 #endif