cosmopolitan/libc/math/modff.c

35 lines
552 B
C

#include "libc/math/libm.h"
float modff(float x, float *iptr)
{
union {float f; uint32_t i;} u = {x};
uint32_t mask;
int e = (int)(u.i>>23 & 0xff) - 0x7f;
/* no fractional part */
if (e >= 23) {
*iptr = x;
if (e == 0x80 && u.i<<9 != 0) { /* nan */
return x;
}
u.i &= 0x80000000;
return u.f;
}
/* no integral part */
if (e < 0) {
u.i &= 0x80000000;
*iptr = u.f;
return x;
}
mask = 0x007fffff>>e;
if ((u.i & mask) == 0) {
*iptr = x;
u.i &= 0x80000000;
return u.f;
}
u.i &= ~mask;
*iptr = u.f;
return x - u.f;
}