github.com/afumu/libc@v0.0.6/musl/src/math/truncf.c (about)

     1  #include "libm.h"
     2  
     3  float truncf(float x)
     4  {
     5  	union {float f; uint32_t i;} u = {x};
     6  	int e = (int)(u.i >> 23 & 0xff) - 0x7f + 9;
     7  	uint32_t m;
     8  
     9  	if (e >= 23 + 9)
    10  		return x;
    11  	if (e < 9)
    12  		e = 1;
    13  	m = -1U >> e;
    14  	if ((u.i & m) == 0)
    15  		return x;
    16  	FORCE_EVAL(x + 0x1p120f);
    17  	u.i &= ~m;
    18  	return u.f;
    19  }