102 lines
2.4 KiB
C
102 lines
2.4 KiB
C
/*
|
|
* ====================================================
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
|
*
|
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
|
* Permission to use, copy, modify, and distribute this
|
|
* software is freely granted, provided that this notice
|
|
* is preserved.
|
|
* ====================================================
|
|
*
|
|
* From: @(#)s_floor.c 5.1 93/09/24
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
/*
|
|
* floorl(x)
|
|
* Return x rounded toward -inf to integral value
|
|
* Method:
|
|
* Bit twiddling.
|
|
* Exception:
|
|
* Inexact flag raised if x not equal to floorl(x).
|
|
*/
|
|
|
|
#include <float.h>
|
|
#include <math.h>
|
|
#include <stdint.h>
|
|
|
|
#include "fpmath.h"
|
|
|
|
#ifdef LDBL_IMPLICIT_NBIT
|
|
#define MANH_SIZE (LDBL_MANH_SIZE + 1)
|
|
#define INC_MANH(u, c) do { \
|
|
uint64_t o = u.bits.manh; \
|
|
u.bits.manh += (c); \
|
|
if (u.bits.manh < o) \
|
|
u.bits.exp++; \
|
|
} while (0)
|
|
#else
|
|
#define MANH_SIZE LDBL_MANH_SIZE
|
|
#define INC_MANH(u, c) do { \
|
|
uint64_t o = u.bits.manh; \
|
|
u.bits.manh += (c); \
|
|
if (u.bits.manh < o) { \
|
|
u.bits.exp++; \
|
|
u.bits.manh |= 1llu << (LDBL_MANH_SIZE - 1); \
|
|
} \
|
|
} while (0)
|
|
#endif
|
|
|
|
static const long double huge = 1.0e300;
|
|
|
|
long double
|
|
floorl(long double x)
|
|
{
|
|
union IEEEl2bits u = { .e = x };
|
|
int e = u.bits.exp - LDBL_MAX_EXP + 1;
|
|
|
|
if (e < MANH_SIZE - 1) {
|
|
if (e < 0) { /* raise inexact if x != 0 */
|
|
if (huge + x > 0.0)
|
|
if (u.bits.exp > 0 ||
|
|
(u.bits.manh | u.bits.manl) != 0)
|
|
u.e = u.bits.sign ? -1.0 : 0.0;
|
|
} else {
|
|
uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1);
|
|
if (((u.bits.manh & m) | u.bits.manl) == 0)
|
|
return (x); /* x is integral */
|
|
if (u.bits.sign) {
|
|
#ifdef LDBL_IMPLICIT_NBIT
|
|
if (e == 0)
|
|
u.bits.exp++;
|
|
else
|
|
#endif
|
|
INC_MANH(u, 1llu << (MANH_SIZE - e - 1));
|
|
}
|
|
if (huge + x > 0.0) { /* raise inexact flag */
|
|
u.bits.manh &= ~m;
|
|
u.bits.manl = 0;
|
|
}
|
|
}
|
|
} else if (e < LDBL_MANT_DIG - 1) {
|
|
uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1);
|
|
if ((u.bits.manl & m) == 0)
|
|
return (x); /* x is integral */
|
|
if (u.bits.sign) {
|
|
if (e == MANH_SIZE - 1)
|
|
INC_MANH(u, 1);
|
|
else {
|
|
uint64_t o = u.bits.manl;
|
|
u.bits.manl += 1llu << (LDBL_MANT_DIG - e - 1);
|
|
if (u.bits.manl < o) /* got a carry */
|
|
INC_MANH(u, 1);
|
|
}
|
|
}
|
|
if (huge + x > 0.0) /* raise inexact flag */
|
|
u.bits.manl &= ~m;
|
|
}
|
|
return (u.e);
|
|
}
|