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 __remquof = remquof
31
32/* INDENT OFF */
33/*
34 * float remquof(float x, float y, int *quo) return remainderf(x,y) and an
35 * integer pointer quo such that *quo = N mod (2**31),  where N is the
36 * exact integeral part of x/y rounded to nearest even.
37 *
38 * remquof call internal fmodquof
39 */
40
41#include "libm.h"
42#include "libm_protos.h"
43#include <math.h>
44extern float fabsf(float);
45
46static const int
47	is = (int) 0x80000000,
48	im = 0x007fffff,
49	ii = 0x7f800000,
50	iu = 0x00800000;
51
52static const float zero = 0.0F, half = 0.5F;
53/* INDENT ON */
54
55static float
56fmodquof(float x, float y, int *quo) {
57	float w;
58	int hx, ix, iy, iz, k, ny, nd, m, sq;
59
60	hx = *(int *) &x;
61	ix = hx & 0x7fffffff;
62	iy = *(int *) &y;
63	sq = (iy ^ hx) & is;	/* sign of x/y */
64	iy &= 0x7fffffff;
65
66	/* purge off exception values */
67	*quo = 0;
68	if (ix >= ii || iy > ii || iy == 0) {
69		w = x * y;
70		w = w / w;
71	} else if (ix <= iy) {
72		if (ix < iy)
73			w = x;	/* return x if |x|<|y| */
74		else {
75			*quo = 1 + (sq >> 30);
76			w = zero * x;	/* return sign(x)*0.0  */
77		}
78	} else {
79		/* INDENT OFF */
80		/*
81		 * scale x,y to "normal" with
82		 *	ny = exponent of y
83		 *	nd = exponent of x minus exponent of y
84		 */
85		/* INDENT ON */
86		ny = iy >> 23;
87		k = ix >> 23;
88
89		/* special case for subnormal y or x */
90		if (ny == 0) {
91			ny = 1;
92			while (iy < iu) {
93				ny -= 1;
94				iy += iy;
95			}
96			nd = k - ny;
97			if (k == 0) {
98				nd += 1;
99				while (ix < iu) {
100					nd -= 1;
101					ix += ix;
102				}
103			} else
104				ix = iu | (ix & im);
105		} else {
106			nd = k - ny;
107			ix = iu | (ix & im);
108			iy = iu | (iy & im);
109		}
110		/* INDENT OFF */
111		/* fix point fmod for normalized ix and iy */
112		/*
113		 * while (nd--) {
114		 *	iz = ix - iy;
115		 *	if (iz < 0)
116		 *		ix = ix + ix;
117		 *	else if (iz == 0) {
118		 *		*(int *) &w = is & hx;
119		 *		return w;
120		 *	} else
121		 *		ix = iz + iz;
122		 * }
123		 */
124		/* INDENT ON */
125		/* unroll the above loop 4 times to gain performance */
126		m = 0;
127		k = nd >> 2;
128		nd -= (k << 2);
129		while (k--) {
130			iz = ix - iy;
131			if (iz >= 0) {
132				m += 1;
133				ix = iz + iz;
134			} else
135				ix += ix;
136			m += m;
137			iz = ix - iy;
138			if (iz >= 0) {
139				m += 1;
140				ix = iz + iz;
141			} else
142				ix += ix;
143			m += m;
144			iz = ix - iy;
145			if (iz >= 0) {
146				m += 1;
147				ix = iz + iz;
148			} else
149				ix += ix;
150			m += m;
151			iz = ix - iy;
152			if (iz >= 0) {
153				m += 1;
154				ix = iz + iz;
155			} else
156				ix += ix;
157			m += m;
158			if (iz == 0) {
159				iz = (k << 2) + nd;
160				if (iz < 32)
161					m <<= iz;
162				else
163					m = 0;
164				m &= 0x7fffffff;
165				*quo = sq >= 0 ? m : -m;
166				*(int *) &w = is & hx;
167				return (w);
168			}
169		}
170		while (nd--) {
171			iz = ix - iy;
172			if (iz >= 0) {
173				m += 1;
174				ix = iz + iz;
175			} else
176				ix += ix;
177			m += m;
178		}
179		/* end of unrolling */
180
181		iz = ix - iy;
182		if (iz >= 0) {
183			m += 1;
184			ix = iz;
185		}
186		m &= 0x7fffffff;
187		*quo = sq >= 0 ? m : -m;
188
189		/* convert back to floating value and restore the sign */
190		if (ix == 0) {
191			*(int *) &w = is & hx;
192			return (w);
193		}
194		while (ix < iu) {
195			ix += ix;
196			ny -= 1;
197		}
198		while (ix > (iu + iu)) {
199			ny += 1;
200			ix >>= 1;
201		}
202		if (ny > 0)
203			*(int *) &w = (is & hx) | (ix & im) | (ny << 23);
204		else {		/* subnormal output */
205			k = -ny + 1;
206			ix >>= k;
207			*(int *) &w = (is & hx) | ix;
208		}
209	}
210	return (w);
211}
212
213float
214remquof(float x, float y, int *quo) {
215	int hx, hy, sx, sq;
216	float v;
217
218	hx = *(int *) &x;	/* high word of x */
219	hy = *(int *) &y;	/* high word of y */
220	sx = hx & is;		/* sign of x */
221	sq = (hx ^ hy) & is;	/* sign of x/y */
222	hx ^= sx;		/* |x| */
223	hy &= 0x7fffffff;	/* |y| */
224
225	/* purge off exception values: y is 0 or NaN, x is Inf or NaN */
226	*quo = 0;
227	if (hx >= ii || hy > ii || hy == 0) {
228		v = x * y;
229		return (v / v);
230	}
231
232	y = fabsf(y);
233	x = fabsf(x);
234	if (hy <= 0x7f7fffff) {
235		x = fmodquof(x, y + y, quo);
236		*quo = ((*quo) & 0x3fffffff) << 1;
237	}
238	if (hy < 0x01000000) {
239		if (x + x > y) {
240			*quo += 1;
241			if (x == y)
242				x = zero;
243			else
244				x -= y;
245			if (x + x >= y) {
246				x -= y;
247				*quo += 1;
248			}
249		}
250	} else {
251		v = half * y;
252		if (x > v) {
253			*quo += 1;
254			if (x == y)
255				x = zero;
256			else
257				x -= y;
258			if (x >= v) {
259				x -= y;
260				*quo += 1;
261			}
262		}
263	}
264	if (sq != 0)
265		*quo = -(*quo);
266	return (sx == 0 ? x : -x);
267}
268