fmodl.c revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma weak fmodl = __fmodl
#include "libm.h"
static const int
is = -0x7fffffff - 1,
im = 0x0000ffff,
iu = 0x00010000;
static const long double
zero = 0.0L,
one = 1.0L;
#ifdef __LITTLE_ENDIAN
#define __H0(x) *(3 + (int *) &x)
#define __H1(x) *(2 + (int *) &x)
#define __H2(x) *(1 + (int *) &x)
#define __H3(x) *(0 + (int *) &x)
#else
#define __H0(x) *(0 + (int *) &x)
#define __H1(x) *(1 + (int *) &x)
#define __H2(x) *(2 + (int *) &x)
#define __H3(x) *(3 + (int *) &x)
#endif
long double
fmodl(long double x, long double y) {
long double a, b;
int n, ix, iy, k, sx;
int hx;
int x0, y0, z0, carry;
unsigned x1, x2, x3, y1, y2, y3, z1, z2, z3;
hx = __H0(x);
x1 = __H1(x);
x2 = __H2(x);
x3 = __H3(x);
y0 = __H0(y);
y1 = __H1(y);
y2 = __H2(y);
y3 = __H3(y);
sx = hx & 0x80000000;
x0 = hx ^ sx;
y0 &= 0x7fffffff;
/* purge off exception values */
if (x0 >= 0x7fff0000 || /* !finitel(x) */
(y0 > 0x7fff0000) || (y0 == 0x7fff0000 && ((y1 | y2 | y3) != 0)) ||
(y0 | y1 | y2 | y3) == 0) /* isnanl(y) || y = 0 */
return ((x * y) / (x * y));
a = fabsl(x);
b = fabsl(y);
if (a <= b) {
if (a < b)
return (x);
else
return (zero * x);
}
/* determine ix = ilogbl(x) */
if (x0 < iu) { /* subnormal x */
ix = -16382;
while (x0 == 0) {
ix -= 16;
x0 = x1 >> 16;
x1 = (x1 << 16) | (x2 >> 16);
x2 = (x2 << 16) | (x3 >> 16);
x3 = (x3 << 16);
}
while (x0 < iu) {
ix -= 1;
x0 = (x0 << 1) | (x1 >> 31);
x1 = (x1 << 1) | (x2 >> 31);
x2 = (x2 << 1) | (x3 >> 31);
x3 <<= 1;
}
} else {
ix = (x0 >> 16) - 16383;
x0 = iu | (x0 & im);
}
/* determine iy = ilogbl(y) */
if (y0 < iu) { /* subnormal y */
iy = -16382;
while (y0 == 0) {
iy -= 16;
y0 = y1 >> 16;
y1 = (y1 << 16) | (y2 >> 16);
y2 = (y2 << 16) | (y3 >> 16);
y3 = (y3 << 16);
}
while (y0 < iu) {
iy -= 1;
y0 = (y0 << 1) | (y1 >> 31);
y1 = (y1 << 1) | (y2 >> 31);
y2 = (y2 << 1) | (y3 >> 31);
y3 <<= 1;
}
} else {
iy = (y0 >> 16) - 16383;
y0 = iu | (y0 & im);
}
/* fix point fmod */
n = ix - iy;
while (n--) {
while (x0 == 0 && n >= 16) {
n -= 16;
x0 = x1 >> 16;
x1 = (x1 << 16) | (x2 >> 16);
x2 = (x2 << 16) | (x3 >> 16);
x3 = (x3 << 16);
}
while (x0 < iu && n >= 1) {
n -= 1;
x0 = (x0 << 1) | (x1 >> 31);
x1 = (x1 << 1) | (x2 >> 31);
x2 = (x2 << 1) | (x3 >> 31);
x3 = (x3 << 1);
}
carry = 0;
z3 = x3 - y3;
carry = (z3 > x3);
if (carry == 0) {
z2 = x2 - y2;
carry = (z2 > x2);
} else {
z2 = x2 - y2 - 1;
carry = (z2 >= x2);
}
if (carry == 0) {
z1 = x1 - y1;
carry = (z1 > x1);
} else {
z1 = x1 - y1 - 1;
carry = (z1 >= x1);
}
z0 = x0 - y0 - carry;
if (z0 < 0) { /* double x */
x0 = x0 + x0 + ((x1 & is) != 0);
x1 = x1 + x1 + ((x2 & is) != 0);
x2 = x2 + x2 + ((x3 & is) != 0);
x3 = x3 + x3;
} else {
if (z0 == 0) {
if ((z1 | z2 | z3) == 0) { /* 0: done */
__H0(a) = hx & is;
__H1(a) = __H2(a) = __H3(a) = 0;
return (a);
}
}
/* x = z << 1 */
z0 = z0 + z0 + ((z1 & is) != 0);
z1 = z1 + z1 + ((z2 & is) != 0);
z2 = z2 + z2 + ((z3 & is) != 0);
z3 = z3 + z3;
x0 = z0;
x1 = z1;
x2 = z2;
x3 = z3;
}
}
carry = 0;
z3 = x3 - y3;
carry = (z3 > x3);
if (carry == 0) {
z2 = x2 - y2;
carry = (z2 > x2);
} else {
z2 = x2 - y2 - 1;
carry = (z2 >= x2);
}
if (carry == 0) {
z1 = x1 - y1;
carry = (z1 > x1);
} else {
z1 = x1 - y1 - 1;
carry = (z1 >= x1);
}
z0 = x0 - y0 - carry;
if (z0 >= 0) {
x0 = z0;
x1 = z1;
x2 = z2;
x3 = z3;
}
/* convert back to floating value and restore the sign */
if ((x0 | x1 | x2 | x3) == 0) {
__H0(a) = hx & is;
__H1(a) = __H2(a) = __H3(a) = 0;
return (a);
}
while (x0 < iu) {
if (x0 == 0) {
iy -= 16;
x0 = x1 >> 16;
x1 = (x1 << 16) | (x2 >> 16);
x2 = (x2 << 16) | (x3 >> 16);
x3 = (x3 << 16);
} else {
x0 = x0 + x0 + ((x1 & is) != 0);
x1 = x1 + x1 + ((x2 & is) != 0);
x2 = x2 + x2 + ((x3 & is) != 0);
x3 = x3 + x3;
iy -= 1;
}
}
/* normalize output */
if (iy >= -16382) {
__H0(a) = sx | (x0 - iu) | ((iy + 16383) << 16);
__H1(a) = x1;
__H2(a) = x2;
__H3(a) = x3;
} else { /* subnormal output */
n = -16382 - iy;
k = n & 31;
if (k != 0) {
if (k <= 16) {
x3 = (x2 << (32 - k)) | (x3 >> k);
x2 = (x1 << (32 - k)) | (x2 >> k);
x1 = (x0 << (32 - k)) | (x1 >> k);
x0 >>= k;
} else {
x3 = (x2 << (32 - k)) | (x3 >> k);
x2 = (x1 << (32 - k)) | (x2 >> k);
x1 = (x0 << (32 - k)) | (x1 >> k);
x0 = 0;
}
}
while (n >= 32) {
n -= 32;
x3 = x2;
x2 = x1;
x1 = x0;
x0 = 0;
}
__H0(a) = x0 | sx;
__H1(a) = x1;
__H2(a) = x2;
__H3(a) = x3;
a *= one;
}
return (a);
}