src/math/nextafterl.c

   1 #include "libm.h"
   2
   3 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
   4 long double nextafterl(long double x, long double y)
   5 {
   6         return nextafter(x, y);
   7 }
   8 #elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
   9 long double nextafterl(long double x, long double y)
  10 {
  11         union ldshape ux, uy;
  12
  13         if (isnan(x) || isnan(y))
  14                 return x + y;
  15         if (x == y)
  16                 return y;
  17         ux.f = x;
  18         if (x == 0) {
  19                 uy.f = y;
  20                 ux.i.m = 1;
  21                 ux.i.se = uy.i.se & 0x8000;
  22         } else if ((x < y) == !(ux.i.se & 0x8000)) {
  23                 ux.i.m++;
  24                 if (ux.i.m << 1 == 0) {
  25                         ux.i.m = 1ULL << 63;
  26                         ux.i.se++;
  27                 }
  28         } else {
  29                 if (ux.i.m << 1 == 0) {
  30                         ux.i.se--;
  31                         if (ux.i.se)
  32                                 ux.i.m = 0;
  33                 }
  34                 ux.i.m--;
  35         }
  36         /* raise overflow if ux is infinite and x is finite */
  37         if ((ux.i.se & 0x7fff) == 0x7fff)
  38                 return x + x;
  39         /* raise underflow if ux is subnormal or zero */
  40         if ((ux.i.se & 0x7fff) == 0)
  41                 FORCE_EVAL(x*x + ux.f*ux.f);
  42         return ux.f;
  43 }
  44 #elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
  45 long double nextafterl(long double x, long double y)
  46 {
  47         union ldshape ux, uy;
  48
  49         if (isnan(x) || isnan(y))
  50                 return x + y;
  51         if (x == y)
  52                 return y;
  53         ux.f = x;
  54         if (x == 0) {
  55                 uy.f = y;
  56                 ux.i.lo = 1;
  57                 ux.i.se = uy.i.se & 0x8000;
  58         } else if ((x < y) == !(ux.i.se & 0x8000)) {
  59                 ux.i2.lo++;
  60                 if (ux.i2.lo == 0)
  61                         ux.i2.hi++;
  62         } else {
  63                 if (ux.i2.lo == 0)
  64                         ux.i2.hi--;
  65                 ux.i2.lo--;
  66         }
  67         /* raise overflow if ux is infinite and x is finite */
  68         if ((ux.i.se & 0x7fff) == 0x7fff)
  69                 return x + x;
  70         /* raise underflow if ux is subnormal or zero */
  71         if ((ux.i.se & 0x7fff) == 0)
  72                 FORCE_EVAL(x*x + ux.f*ux.f);
  73         return ux.f;
  74 }
  75 #endif