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.h>
  24 #include <math_private.h>
  25 #include <math_ldbl_opt.h>
  26 #include <float.h>
  27
  28 float __nldbl_nexttowardf(float x, double y);
  29
  30 float __nldbl_nexttowardf(float x, double y)
  31 {
  32         int32_t hx,hy,ix,iy;
  33         u_int32_t ly;
  34
  35         GET_FLOAT_WORD(hx,x);
  36         EXTRACT_WORDS(hy,ly,y);
  37         ix = hx&0x7fffffff;             /* |x| */
  38         iy = hy&0x7fffffff;             /* |y| */
  39
  40         if((ix>0x7f800000) ||                              /* x is nan */
  41            ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))    /* y is nan */
  42            return x+y;
  43         if((double) x==y) return y;             /* x=y, return y */
  44         if(ix==0) {                             /* x == 0 */
  45             float u;
  46             SET_FLOAT_WORD(x,(u_int32_t)(hy&0x80000000)|1);/* return +-minsub*/
  47             u = math_opt_barrier (x);
  48             u = u * u;
  49             math_force_eval (u);                /* raise underflow flag */
  50             return x;
  51         }
  52         if(hx>=0) {                             /* x > 0 */
  53             if(hy<0||(ix>>23)>(iy>>20)-0x380
  54                || ((ix>>23)==(iy>>20)-0x380
  55                    && (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff)))     /* x > y, x -= ulp */
  56                 hx -= 1;
  57             else                                /* x < y, x += ulp */
  58                 hx += 1;
  59         } else {                                /* x < 0 */
  60             if(hy>=0||(ix>>23)>(iy>>20)-0x380
  61                || ((ix>>23)==(iy>>20)-0x380
  62                    && (ix&0x7fffff)>(((hy<<3)|(ly>>29))&0x7fffff)))     /* x < y, x -= ulp */
  63                 hx -= 1;
  64             else                                /* x > y, x += ulp */
  65                 hx += 1;
  66         }
  67         hy = hx&0x7f800000;
  68         if(hy>=0x7f800000) {
  69           x = x+x;      /* overflow  */
  70           if (FLT_EVAL_METHOD != 0)
  71             /* Force conversion to float.  */
  72             asm ("" : "+m"(x));
  73           return x;
  74         }
  75         if(hy<0x00800000) {
  76             float u = x*x;                      /* underflow */
  77             math_force_eval (u);                /* raise underflow flag */
  78         }
  79         SET_FLOAT_WORD(x,hx);
  80         return x;
  81 }
  82
  83 #if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
  84 compat_symbol (libm, __nldbl_nexttowardf, nexttowardf, GLIBC_2_1);
  85 #endif