xref: /illumos-gate/usr/src/lib/libm/common/m9x/remquol.c (revision 04427e3bf236c18cc532680b957267ee70b1037d)
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 __remquol = remquol
31 
32 #include "libm.h"
33 #if defined(__SUNPRO_C)
34 #include <sunmath.h>			/* fabsl */
35 #endif
36 /* INDENT OFF */
37 static const int
38 	is = -0x7fffffff - 1,
39 	im = 0x0000ffff,
40 	iu = 0x00010000;
41 
42 static const long double zero = 0.0L, one = 1.0L;
43 /* INDENT ON */
44 
45 #if defined(__sparc)
46 #define	__H0(x)	((int *) &x)[0]
47 #define	__H1(x)	((int *) &x)[1]
48 #define	__H2(x)	((int *) &x)[2]
49 #define	__H3(x)	((int *) &x)[3]
50 #else
51 #error Unsupported architecture
52 #endif
53 
54 /*
55  * On entrance: *quo is initialized to 0, x finite and y non-zero & ordered
56  */
57 static long double
58 fmodquol(long double x, long double y, int *quo) {
59 	long double a, b;
60 	int n, ix, iy, k, sx, sq, m;
61 	int hx;
62 	int x0, y0, z0, carry;
63 	unsigned x1, x2, x3, y1, y2, y3, z1, z2, z3;
64 
65 	hx = __H0(x);
66 	x1 = __H1(x);
67 	x2 = __H2(x);
68 	x3 = __H3(x);
69 	y0 = __H0(y);
70 	y1 = __H1(y);
71 	y2 = __H2(y);
72 	y3 = __H3(y);
73 
74 	sx = hx & is;
75 	sq = (hx ^ y0) & is;
76 	x0 = hx ^ sx;
77 	y0 &= ~0x80000000;
78 
79 	a = fabsl(x);
80 	b = fabsl(y);
81 	if (a <= b) {
82 		if (a < b)
83 			return (x);
84 		else {
85 			*quo = 1 + (sq >> 30);
86 			return (zero * x);
87 		}
88 	}
89 	/* determine ix = ilogbl(x) */
90 	if (x0 < iu) {		/* subnormal x */
91 		ix = 0;
92 		ix = -16382;
93 		while (x0 == 0) {
94 			ix -= 16;
95 			x0 = x1 >> 16;
96 			x1 = (x1 << 16) | (x2 >> 16);
97 			x2 = (x2 << 16) | (x3 >> 16);
98 			x3 = (x3 << 16);
99 		}
100 		while (x0 < iu) {
101 			ix -= 1;
102 			x0 = (x0 << 1) | (x1 >> 31);
103 			x1 = (x1 << 1) | (x2 >> 31);
104 			x2 = (x2 << 1) | (x3 >> 31);
105 			x3 <<= 1;
106 		}
107 	} else {
108 		ix = (x0 >> 16) - 16383;
109 		x0 = iu | (x0 & im);
110 	}
111 
112 	/* determine iy = ilogbl(y) */
113 	if (y0 < iu) {		/* subnormal y */
114 		iy = -16382;
115 		while (y0 == 0) {
116 			iy -= 16;
117 			y0 = y1 >> 16;
118 			y1 = (y1 << 16) | (y2 >> 16);
119 			y2 = (y2 << 16) | (y3 >> 16);
120 			y3 = (y3 << 16);
121 		}
122 		while (y0 < iu) {
123 			iy -= 1;
124 			y0 = (y0 << 1) | (y1 >> 31);
125 			y1 = (y1 << 1) | (y2 >> 31);
126 			y2 = (y2 << 1) | (y3 >> 31);
127 			y3 <<= 1;
128 		}
129 	} else {
130 		iy = (y0 >> 16) - 16383;
131 		y0 = iu | (y0 & im);
132 	}
133 
134 
135 	/* fix point fmod */
136 	n = ix - iy;
137 	m = 0;
138 	while (n--) {
139 		while (x0 == 0 && n >= 16) {
140 			m <<= 16;
141 			n -= 16;
142 			x0 = x1 >> 16;
143 			x1 = (x1 << 16) | (x2 >> 16);
144 			x2 = (x2 << 16) | (x3 >> 16);
145 			x3 = (x3 << 16);
146 		}
147 		while (x0 < iu && n >= 1) {
148 			m += m;
149 			n -= 1;
150 			x0 = (x0 << 1) | (x1 >> 31);
151 			x1 = (x1 << 1) | (x2 >> 31);
152 			x2 = (x2 << 1) | (x3 >> 31);
153 			x3 = (x3 << 1);
154 		}
155 		carry = 0;
156 		z3 = x3 - y3;
157 		carry = z3 > x3;
158 		if (carry == 0) {
159 			z2 = x2 - y2;
160 			carry = z2 > x2;
161 		} else {
162 			z2 = x2 - y2 - 1;
163 			carry = z2 >= x2;
164 		}
165 		if (carry == 0) {
166 			z1 = x1 - y1;
167 			carry = z1 > x1;
168 		} else {
169 			z1 = x1 - y1 - 1;
170 			carry = z1 >= x1;
171 		}
172 		z0 = x0 - y0 - carry;
173 		if (z0 < 0) {	/* double x */
174 			x0 = x0 + x0 + ((x1 & is) != 0);
175 			x1 = x1 + x1 + ((x2 & is) != 0);
176 			x2 = x2 + x2 + ((x3 & is) != 0);
177 			x3 = x3 + x3;
178 			m += m;
179 		} else {
180 			m += 1;
181 			if (z0 == 0) {
182 				if ((z1 | z2 | z3) == 0) {
183 					/* 0: we are done */
184 					if (n < 31)
185 						m <<= (1 + n);
186 					else
187 						m = 0;
188 					m &= ~0x80000000;
189 					*quo = sq >= 0 ? m : -m;
190 					__H0(a) = hx & is;
191 					__H1(a) = __H2(a) = __H3(a) = 0;
192 					return (a);
193 				}
194 			}
195 			/* x = z << 1 */
196 			z0 = z0 + z0 + ((z1 & is) != 0);
197 			z1 = z1 + z1 + ((z2 & is) != 0);
198 			z2 = z2 + z2 + ((z3 & is) != 0);
199 			z3 = z3 + z3;
200 			x0 = z0;
201 			x1 = z1;
202 			x2 = z2;
203 			x3 = z3;
204 			m += m;
205 		}
206 	}
207 	carry = 0;
208 	z3 = x3 - y3;
209 	carry = z3 > x3;
210 	if (carry == 0) {
211 		z2 = x2 - y2;
212 		carry = z2 > x2;
213 	} else {
214 		z2 = x2 - y2 - 1;
215 		carry = z2 >= x2;
216 	}
217 	if (carry == 0) {
218 		z1 = x1 - y1;
219 		carry = z1 > x1;
220 	} else {
221 		z1 = x1 - y1 - 1;
222 		carry = z1 >= x1;
223 	}
224 	z0 = x0 - y0 - carry;
225 	if (z0 >= 0) {
226 		x0 = z0;
227 		x1 = z1;
228 		x2 = z2;
229 		x3 = z3;
230 		m += 1;
231 	}
232 	m &= ~0x80000000;
233 	*quo = sq >= 0 ? m : -m;
234 
235 	/* convert back to floating value and restore the sign */
236 	if ((x0 | x1 | x2 | x3) == 0) {
237 		__H0(a) = hx & is;
238 		__H1(a) = __H2(a) = __H3(a) = 0;
239 		return (a);
240 	}
241 	while (x0 < iu) {
242 		if (x0 == 0) {
243 			iy -= 16;
244 			x0 = x1 >> 16;
245 			x1 = (x1 << 16) | (x2 >> 16);
246 			x2 = (x2 << 16) | (x3 >> 16);
247 			x3 = (x3 << 16);
248 		} else {
249 			x0 = x0 + x0 + ((x1 & is) != 0);
250 			x1 = x1 + x1 + ((x2 & is) != 0);
251 			x2 = x2 + x2 + ((x3 & is) != 0);
252 			x3 = x3 + x3;
253 			iy -= 1;
254 		}
255 	}
256 
257 	/* normalize output */
258 	if (iy >= -16382) {
259 		__H0(a) = sx | (x0 - iu) | ((iy + 16383) << 16);
260 		__H1(a) = x1;
261 		__H2(a) = x2;
262 		__H3(a) = x3;
263 	} else {		/* subnormal output */
264 		n = -16382 - iy;
265 		k = n & 31;
266 		if (k <= 16) {
267 			x3 = (x2 << (32 - k)) | (x3 >> k);
268 			x2 = (x1 << (32 - k)) | (x2 >> k);
269 			x1 = (x0 << (32 - k)) | (x1 >> k);
270 			x0 >>= k;
271 		} else {
272 			x3 = (x2 << (32 - k)) | (x3 >> k);
273 			x2 = (x1 << (32 - k)) | (x2 >> k);
274 			x1 = (x0 << (32 - k)) | (x1 >> k);
275 			x0 = 0;
276 		}
277 		while (n >= 32) {
278 			n -= 32;
279 			x3 = x2;
280 			x2 = x1;
281 			x1 = x0;
282 			x0 = 0;
283 		}
284 		__H0(a) = x0 | sx;
285 		__H1(a) = x1;
286 		__H2(a) = x2;
287 		__H3(a) = x3;
288 		a *= one;
289 	}
290 	return (a);
291 }
292 
293 long double
294 remquol(long double x, long double y, int *quo) {
295 	int hx, hy, sx, sq;
296 	long double v;
297 
298 	hx = __H0(x);		/* high word of x */
299 	hy = __H0(y);		/* high word of y */
300 	sx = hx & is;		/* sign of x */
301 	sq = (hx ^ hy) & is;	/* sign of x/y */
302 	hx ^= sx;		/* |x| */
303 	hy &= ~0x80000000;
304 
305 	/* purge off exception values */
306 	*quo = 0;
307 	/* y=0, y is NaN, x is NaN or inf */
308 	if (y == 0.0L || y != y || hx >= 0x7fff0000)
309 		return ((x * y) / (x * y));
310 
311 	y = fabsl(y);
312 	x = fabsl(x);
313 	if (hy <= 0x7ffdffff) {
314 		x = fmodquol(x, y + y, quo);
315 		*quo = ((*quo) & 0x3fffffff) << 1;
316 	}
317 	if (hy < 0x00020000) {
318 		if (x + x > y) {
319 			*quo += 1;
320 			if (x == y)
321 				x = zero;
322 			else
323 				x -= y;
324 			if (x + x >= y) {
325 				x -= y;
326 				*quo += 1;
327 			}
328 		}
329 	} else {
330 		v = 0.5L * y;
331 		if (x > v) {
332 			*quo += 1;
333 			if (x == y)
334 				x = zero;
335 			else
336 				x -= y;
337 			if (x >= v) {
338 				x -= y;
339 				*quo += 1;
340 			}
341 		}
342 	}
343 	if (sq != 0)
344 		*quo = -(*quo);
345 	return (sx == 0 ? x : -x);
346 }
347