lib/libm/truncf.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

#include "libm.h" // for FORCE_EVAL

#include <math.h>   // for truncf
#include <stdint.h> // for uint32_t

float truncf(float x)
{
	union {
		float f;
		uint32_t i;
	} u = { x };
	int e = (int)(u.i >> 23 & 0xff) - 0x7f + 9;
	uint32_t m;

	if (e >= 23 + 9)
		return x;
	if (e < 9)
		e = 1;
	m = -1U >> e;
	if ((u.i & m) == 0)
		return x;
	FORCE_EVAL(x + 0x1p120f);
	u.i &= ~m;
	return u.f;
}