| #include "libm.h" |
| |
| #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024 |
| double nexttoward(double x, long double y) |
| { |
| return nextafter(x, y); |
| } |
| #else |
| double nexttoward(double x, long double y) |
| { |
| union {double f; uint64_t i;} ux = {x}; |
| int e; |
| |
| if (isnan(x) || isnan(y)) |
| return x + y; |
| if (x == y) |
| return y; |
| if (x == 0) { |
| ux.i = 1; |
| if (signbit(y)) |
| ux.i |= 1ULL<<63; |
| } else if (x < y) { |
| if (signbit(x)) |
| ux.i--; |
| else |
| ux.i++; |
| } else { |
| if (signbit(x)) |
| ux.i++; |
| else |
| ux.i--; |
| } |
| e = ux.i>>52 & 0x7ff; |
| /* raise overflow if ux.f is infinite and x is finite */ |
| if (e == 0x7ff) |
| FORCE_EVAL(x+x); |
| /* raise underflow if ux.f is subnormal or zero */ |
| if (e == 0) |
| FORCE_EVAL(x*x + ux.f*ux.f); |
| return ux.f; |
| } |
| #endif |
