1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
24 */
25/*
26 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
27 * Use is subject to license terms.
28 */
29
30#pragma weak __remquo = remquo
31
32/* INDENT OFF */
33/*
34 * double remquo(double x, double y, int *quo) return remainder(x,y) and an
35 * integer pointer quo such that *quo = N mod {2**31}, where N is the
36 * exact integral part of x/y rounded to nearest even.
37 *
38 * remquo call internal fmodquo
39 */
40/* INDENT ON */
41
42#include "libm.h"
43#include "libm_protos.h"
44#include <math.h>		/* fabs() */
45#include <sys/isa_defs.h>
46
47#if defined(_BIG_ENDIAN)
48#define	HIWORD	0
49#define	LOWORD	1
50#else
51#define	HIWORD	1
52#define	LOWORD	0
53#endif
54#define	__HI(x)	((int *) &x)[HIWORD]
55#define	__LO(x)	((int *) &x)[LOWORD]
56
57static const double one = 1.0, Zero[] = {0.0, -0.0};
58
59static double
60fmodquo(double x, double y, int *quo) {
61	int n, hx, hy, hz, ix, iy, sx, sq, i, m;
62	unsigned lx, ly, lz;
63
64	hx = __HI(x);		/* high word of x */
65	lx = __LO(x);		/* low  word of x */
66	hy = __HI(y);		/* high word of y */
67	ly = __LO(y);		/* low  word of y */
68	sx = hx & 0x80000000;	/* sign of x */
69	sq = (hx ^ hy) & 0x80000000;	/* sign of x/y */
70	hx ^= sx;		/* |x| */
71	hy &= 0x7fffffff;	/* |y| */
72
73	/* purge off exception values */
74	*quo = 0;
75	if ((hy | ly) == 0 || hx >= 0x7ff00000 ||	/* y=0, or x !finite */
76	    (hy | ((ly | -ly) >> 31)) > 0x7ff00000)	/* or y is NaN */
77		return ((x * y) / (x * y));
78	if (hx <= hy) {
79		if (hx < hy || lx < ly)
80			return (x);	/* |x|<|y| return x */
81		if (lx == ly) {
82			*quo = 1 + (sq >> 30);
83			/* |x|=|y| return x*0 */
84			return (Zero[(unsigned) sx >> 31]);
85		}
86	}
87
88	/* determine ix = ilogb(x) */
89	if (hx < 0x00100000) {	/* subnormal x */
90		if (hx == 0) {
91			for (ix = -1043, i = lx; i > 0; i <<= 1)
92				ix -= 1;
93		} else {
94			for (ix = -1022, i = (hx << 11); i > 0; i <<= 1)
95				ix -= 1;
96		}
97	} else
98		ix = (hx >> 20) - 1023;
99
100	/* determine iy = ilogb(y) */
101	if (hy < 0x00100000) {	/* subnormal y */
102		if (hy == 0) {
103			for (iy = -1043, i = ly; i > 0; i <<= 1)
104				iy -= 1;
105		} else {
106			for (iy = -1022, i = (hy << 11); i > 0; i <<= 1)
107				iy -= 1;
108		}
109	} else
110		iy = (hy >> 20) - 1023;
111
112	/* set up {hx,lx}, {hy,ly} and align y to x */
113	if (ix >= -1022)
114		hx = 0x00100000 | (0x000fffff & hx);
115	else {			/* subnormal x, shift x to normal */
116		n = -1022 - ix;
117		if (n <= 31) {
118			hx = (hx << n) | (lx >> (32 - n));
119			lx <<= n;
120		} else {
121			hx = lx << (n - 32);
122			lx = 0;
123		}
124	}
125	if (iy >= -1022)
126		hy = 0x00100000 | (0x000fffff & hy);
127	else {			/* subnormal y, shift y to normal */
128		n = -1022 - iy;
129		if (n <= 31) {
130			hy = (hy << n) | (ly >> (32 - n));
131			ly <<= n;
132		} else {
133			hy = ly << (n - 32);
134			ly = 0;
135		}
136	}
137
138	/* fix point fmod */
139	n = ix - iy;
140	m = 0;
141	while (n--) {
142		hz = hx - hy;
143		lz = lx - ly;
144		if (lx < ly)
145			hz -= 1;
146		if (hz < 0) {
147			hx = hx + hx + (lx >> 31);
148			lx = lx + lx;
149		} else {
150			m += 1;
151			if ((hz | lz) == 0) {	/* return sign(x)*0 */
152				if (n < 31)
153					m <<= 1 + n;
154				else
155					m = 0;
156				m &= 0x7fffffff;
157				*quo = sq >= 0 ? m : -m;
158				return (Zero[(unsigned) sx >> 31]);
159			}
160			hx = hz + hz + (lz >> 31);
161			lx = lz + lz;
162		}
163		m += m;
164	}
165	hz = hx - hy;
166	lz = lx - ly;
167	if (lx < ly)
168		hz -= 1;
169	if (hz >= 0) {
170		hx = hz;
171		lx = lz;
172		m += 1;
173	}
174	m &= 0x7fffffff;
175	*quo = sq >= 0 ? m : -m;
176
177	/* convert back to floating value and restore the sign */
178	if ((hx | lx) == 0) {	/* return sign(x)*0 */
179		return (Zero[(unsigned) sx >> 31]);
180	}
181	while (hx < 0x00100000) {	/* normalize x */
182		hx = hx + hx + (lx >> 31);
183		lx = lx + lx;
184		iy -= 1;
185	}
186	if (iy >= -1022) {	/* normalize output */
187		hx = (hx - 0x00100000) | ((iy + 1023) << 20);
188		__HI(x) = hx | sx;
189		__LO(x) = lx;
190	} else {			/* subnormal output */
191		n = -1022 - iy;
192		if (n <= 20) {
193			lx = (lx >> n) | ((unsigned) hx << (32 - n));
194			hx >>= n;
195		} else if (n <= 31) {
196			lx = (hx << (32 - n)) | (lx >> n);
197			hx = sx;
198		} else {
199			lx = hx >> (n - 32);
200			hx = sx;
201		}
202		__HI(x) = hx | sx;
203		__LO(x) = lx;
204		x *= one;	/* create necessary signal */
205	}
206	return (x);		/* exact output */
207}
208
209#define	zero	Zero[0]
210
211double
212remquo(double x, double y, int *quo) {
213	int hx, hy, sx, sq;
214	double v;
215	unsigned ly;
216
217	hx = __HI(x);		/* high word of x */
218	hy = __HI(y);		/* high word of y */
219	ly = __LO(y);		/* low  word of y */
220	sx = hx & 0x80000000;	/* sign of x */
221	sq = (hx ^ hy) & 0x80000000;	/* sign of x/y */
222	hx ^= sx;		/* |x| */
223	hy &= 0x7fffffff;	/* |y| */
224
225	/* purge off exception values */
226	*quo = 0;
227	if ((hy | ly) == 0 || hx >= 0x7ff00000 ||	/* y=0, or x !finite */
228	    (hy | ((ly | -ly) >> 31)) > 0x7ff00000)	/* or y is NaN */
229		return ((x * y) / (x * y));
230
231	y = fabs(y);
232	x = fabs(x);
233	if (hy <= 0x7fdfffff) {
234		x = fmodquo(x, y + y, quo);
235		*quo = ((*quo) & 0x3fffffff) << 1;
236	}
237	if (hy < 0x00200000) {
238		if (x + x > y) {
239			*quo += 1;
240			if (x == y)
241				x = zero;
242			else
243				x -= y;
244			if (x + x >= y) {
245				x -= y;
246				*quo += 1;
247			}
248		}
249	} else {
250		v = 0.5 * y;
251		if (x > v) {
252			*quo += 1;
253			if (x == y)
254				x = zero;
255			else
256				x -= y;
257			if (x >= v) {
258				x -= y;
259				*quo += 1;
260			}
261		}
262	}
263	if (sq != 0)
264		*quo = -(*quo);
265	return (sx == 0 ? x : -x);
266}
267