| #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 |