cosmopolitan/libc/math/nexttowardf.c

36 lines
626 B
C

#include "libc/math/libm.h"
float nexttowardf(float x, long double y)
{
union {float f; uint32_t i;} ux = {x};
uint32_t 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 |= 0x80000000;
} else if (x < y) {
if (signbit(x))
ux.i--;
else
ux.i++;
} else {
if (signbit(x))
ux.i++;
else
ux.i--;
}
e = ux.i & 0x7f800000;
/* raise overflow if ux.f is infinite and x is finite */
if (e == 0x7f800000)
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;
}