xref: /illumos-gate/usr/src/lib/libnsl/rpc/xdr_float.c (revision 8b80e8cb6855118d46f605e91b5ed4ce83417395)
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 2006 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
28 /* All Rights Reserved */
29 /*
30  * Portions of this source code were derived from Berkeley
31  * 4.3 BSD under license from the Regents of the University of
32  * California.
33  */
34 
35 #pragma ident	"%Z%%M%	%I%	%E% SMI"
36 
37 /*
38  * Generic XDR routines impelmentation.
39  *
40  * These are the "floating point" xdr routines used to (de)serialize
41  * most common data items.  See xdr.h for more info on the interface to
42  * xdr.
43  */
44 
45 #include "mt.h"
46 #include <sys/types.h>
47 #include <stdio.h>
48 #include <rpc/types.h>
49 #include <rpc/xdr.h>
50 
51 /*
52  * This routine works on Suns, 3b2, 68000s, 386 and Vaxen in a manner
53  * which is very efficient as bit twiddling is all that is needed.  All
54  * other machines can use this code but the code is inefficient as
55  * various mathematical operations are used to generate the ieee format.
56  * In addition rounding errors may occur due to the calculations involved.
57  * To be most efficient, new machines should have their own ifdefs.
58  * The encoding routines will fail if the machines try to encode a
59  * float/double whose value can not be represented by the ieee format,
60  * e.g. the exponent is too big/small.
61  *	ieee largest  float  = (2 ^ 128)  * 0x1.fffff
62  *	ieee smallest float  = (2 ^ -127) * 0x1.00000
63  *	ieee largest  double = (2 ^ 1024)  * 0x1.fffff
64  *	ieee smallest double = (2 ^ -1023) * 0x1.00000
65  * The decoding routines assumes that the receiving machine can handle
66  * floats/doubles as large/small as the values stated above.  If you
67  * use a machine which can not represent these values, you will need
68  * to put ifdefs in the decode sections to identify areas of failure.
69  */
70 
71 #if defined(vax)
72 
73 /*
74  * What IEEE single precision floating point looks like this on a
75  * vax.
76  */
77 
78 struct	ieee_single {
79 	unsigned int	mantissa: 23;
80 	unsigned int	exp	: 8;
81 	unsigned int	sign    : 1;
82 };
83 
84 #define	IEEE_SNG_BIAS	0x7f
85 #define	VAX_SNG_BIAS    0x81
86 
87 
88 /* Vax single precision floating point */
89 struct	vax_single {
90 	unsigned int	mantissa1 : 7;
91 	unsigned int	exp	: 8;
92 	unsigned int	sign	: 1;
93 	unsigned int	mantissa2 : 16;
94 };
95 
96 #define	VAX_SNG_BIAS	0x81
97 
98 static struct sgl_limits {
99 	struct vax_single s;
100 	struct ieee_single ieee;
101 } sgl_limits[2] = {
102 	{{ 0x7f, 0xff, 0x0, 0xffff },	/* Max Vax */
103 	{ 0x0, 0xff, 0x0 }},		/* Max IEEE */
104 	{{ 0x0, 0x0, 0x0, 0x0 },	/* Min Vax */
105 	{ 0x0, 0x0, 0x0 }}		/* Min IEEE */
106 };
107 #endif /* vax */
108 
109 bool_t
110 xdr_float(XDR *xdrs, float *fp)
111 {
112 #if defined(vax)
113 	struct ieee_single is;
114 	struct vax_single vs, *vsp;
115 	struct sgl_limits *lim;
116 	size_t i;
117 #endif
118 
119 	switch (xdrs->x_op) {
120 
121 	case XDR_ENCODE:
122 #if defined(mc68000) || defined(sparc) || defined(u3b2) || \
123 	defined(u3b15) || defined(i386) || defined(amd64)
124 		return (XDR_PUTINT32(xdrs, (int *)fp));
125 #else
126 #if defined(vax)
127 		vs = *((struct vax_single *)fp);
128 		if ((vs.exp == 1) || (vs.exp == 2)) {
129 			/* map these to subnormals */
130 			is.exp = 0;
131 			is.mantissa = (vs.mantissa1 << 16) | vs.mantissa2;
132 			/* lose some precision */
133 			is.mantissa >>= 3 - vs.exp;
134 			is.mantissa += (1 << (20 + vs.exp));
135 			goto shipit;
136 		}
137 		for (i = 0, lim = sgl_limits;
138 			i < (int)(sizeof (sgl_limits) /
139 					sizeof (struct sgl_limits));
140 			i++, lim++) {
141 			if ((vs.mantissa2 == lim->s.mantissa2) &&
142 				(vs.exp == lim->s.exp) &&
143 				(vs.mantissa1 == lim->s.mantissa1)) {
144 				is = lim->ieee;
145 				goto shipit;
146 			}
147 		}
148 		is.exp = vs.exp - VAX_SNG_BIAS + IEEE_SNG_BIAS;
149 		is.mantissa = (vs.mantissa1 << 16) | vs.mantissa2;
150 	shipit:
151 		is.sign = vs.sign;
152 		return (XDR_PUTINT32(xdrs, (int32_t *)&is));
153 #else
154 		{
155 		/*
156 		 * Every machine can do this, its just not very efficient.
157 		 * In addtion, some rounding errors may occur do to the
158 		 * calculations involved.
159 		 */
160 		float f;
161 		int neg = 0;
162 		int exp = 0;
163 		int32_t val;
164 
165 		f = *fp;
166 		if (f == 0) {
167 			val = 0;
168 			return (XDR_PUTINT32(xdrs, &val));
169 		}
170 		if (f < 0) {
171 			f = 0 - f;
172 			neg = 1;
173 		}
174 		while (f < 1) {
175 			f = f * 2;
176 			--exp;
177 		}
178 		while (f >= 2) {
179 			f = f/2;
180 			++exp;
181 		}
182 		if ((exp > 128) || (exp < -127)) {
183 			/* over or under flowing ieee exponent */
184 			return (FALSE);
185 		}
186 		val = neg;
187 		val = val << 8;		/* for the exponent */
188 		val += 127 + exp;	/* 127 is the bias */
189 		val = val << 23;	/* for the mantissa */
190 		val += (int32_t)((f - 1) * 8388608);	/* 2 ^ 23 */
191 		return (XDR_PUTINT32(xdrs, &val));
192 		}
193 #endif
194 #endif
195 
196 	case XDR_DECODE:
197 #if defined(mc68000) || defined(sparc) || defined(u3b2) || \
198 	defined(u3b15) || defined(i386) || defined(amd64)
199 		return (XDR_GETINT32(xdrs, (int *)fp));
200 #else
201 #if defined(vax)
202 		vsp = (struct vax_single *)fp;
203 		if (!XDR_GETINT32(xdrs, (int32_t *)&is))
204 			return (FALSE);
205 
206 		for (i = 0, lim = sgl_limits;
207 			i < (int)(sizeof (sgl_limits) /
208 					sizeof (struct sgl_limits));
209 			i++, lim++) {
210 			if ((is.exp == lim->ieee.exp) &&
211 				(is.mantissa == lim->ieee.mantissa)) {
212 				*vsp = lim->s;
213 				goto doneit;
214 			} else if ((is.exp == 0) && (lim->ieee.exp == 0)) {
215 			    /* Special Case */
216 			    unsigned tmp = is.mantissa >> 20;
217 			    if (tmp >= 4) {
218 			    vsp->exp = 2;
219 			    } else if (tmp >= 2) {
220 			    vsp->exp = 1;
221 			    } else {
222 				*vsp = min.s;
223 				break;
224 			    }	/* else */
225 			    tmp = is.mantissa - (1 << (20 + vsp->exp));
226 			    tmp <<= 3 - vsp->exp;
227 			    vsp->mantissa2 = tmp;
228 			    vsp->mantissa1 = (tmp >> 16);
229 			    goto doneit;
230 		    }
231 		vsp->exp = is.exp - IEEE_SNG_BIAS + VAX_SNG_BIAS;
232 		vsp->mantissa2 = is.mantissa;
233 		vsp->mantissa1 = (is.mantissa >> 16);
234 	doneit:
235 		vsp->sign = is.sign;
236 		return (TRUE);
237 #else
238 		{
239 		/*
240 		 * Every machine can do this, its just not very
241 		 * efficient.  It assumes that the decoding machine's
242 		 * float can represent any value in the range of
243 		 *	ieee largest  float  = (2 ^ 128)  * 0x1.fffff
244 		 *	to
245 		 *	ieee smallest float  = (2 ^ -127) * 0x1.00000
246 		 * In addtion, some rounding errors may occur do to the
247 		 * calculations involved.
248 		 */
249 		float f;
250 		int neg = 0;
251 		int exp = 0;
252 		int32_t val;
253 
254 		if (!XDR_GETINT32(xdrs, (int32_t *)&val))
255 			return (FALSE);
256 		neg = val & 0x80000000;
257 		exp = (val & 0x7f800000) >> 23;
258 		exp -= 127;		/* subtract exponent base */
259 		f = (val & 0x007fffff) * 0.00000011920928955078125;
260 		/* 2 ^ -23 */
261 		f++;
262 		while (exp != 0) {
263 			if (exp < 0) {
264 				f = f/2.0;
265 				++exp;
266 			} else {
267 				f = f * 2.0;
268 				--exp;
269 			}
270 		}
271 		if (neg)
272 			f = 0 - f;
273 		*fp = f;
274 		}
275 		return (TRUE);
276 #endif
277 #endif
278 
279 	case XDR_FREE:
280 		return (TRUE);
281 	}
282 	return (FALSE);
283 }
284 
285 /*
286  * This routine works on Suns (Sky / 68000's) and Vaxen.
287  */
288 
289 #if defined(vax)
290 /* What IEEE double precision floating point looks like on a Vax */
291 struct	ieee_double {
292 	unsigned int	mantissa1 : 20;
293 	unsigned int	exp	  : 11;
294 	unsigned int	sign	  : 1;
295 	unsigned int	mantissa2 : 32;
296 };
297 
298 /* Vax double precision floating point */
299 struct  vax_double {
300 	unsigned int	mantissa1 : 7;
301 	unsigned int	exp	  : 8;
302 	unsigned int	sign	  : 1;
303 	unsigned int	mantissa2 : 16;
304 	unsigned int	mantissa3 : 16;
305 	unsigned int	mantissa4 : 16;
306 };
307 
308 #define	VAX_DBL_BIAS	0x81
309 #define	IEEE_DBL_BIAS	0x3ff
310 #define	MASK(nbits)	((1 << nbits) - 1)
311 
312 static struct dbl_limits {
313 	struct	vax_double d;
314 	struct	ieee_double ieee;
315 } dbl_limits[2] = {
316 	{{ 0x7f, 0xff, 0x0, 0xffff, 0xffff, 0xffff },	/* Max Vax */
317 	{ 0x0, 0x7ff, 0x0, 0x0 }},			/* Max IEEE */
318 	{{ 0x0, 0x0, 0x0, 0x0, 0x0, 0x0},		/* Min Vax */
319 	{ 0x0, 0x0, 0x0, 0x0 }}				/* Min IEEE */
320 };
321 
322 #endif /* vax */
323 
324 
325 bool_t
326 xdr_double(XDR *xdrs, double *dp)
327 {
328 	int *lp;
329 #if defined(vax)
330 	struct	ieee_double id;
331 	struct	vax_double vd;
332 	struct dbl_limits *lim;
333 	size_t i;
334 #endif
335 
336 	switch (xdrs->x_op) {
337 
338 	case XDR_ENCODE:
339 #if defined(mc68000) || defined(u3b2) || defined(u3b15) || \
340 	defined(_LONG_LONG_HTOL)
341 		lp = (int *)dp;
342 		return (XDR_PUTINT32(xdrs, lp++) && XDR_PUTINT32(xdrs, lp));
343 #else
344 #if defined(_LONG_LONG_LTOH)
345 		lp = (int *)dp;
346 		lp++;
347 		return (XDR_PUTINT32(xdrs, lp--) && XDR_PUTINT32(xdrs, lp));
348 #else
349 #if defined(vax)
350 		vd = *((struct vax_double *)dp);
351 		for (i = 0, lim = dbl_limits;
352 			i < (int)(sizeof (dbl_limits) /
353 					sizeof (struct dbl_limits));
354 			i++, lim++) {
355 			if ((vd.mantissa4 == lim->d.mantissa4) &&
356 				(vd.mantissa3 == lim->d.mantissa3) &&
357 				(vd.mantissa2 == lim->d.mantissa2) &&
358 				(vd.mantissa1 == lim->d.mantissa1) &&
359 				(vd.exp == lim->d.exp)) {
360 				id = lim->ieee;
361 				goto shipit;
362 			}
363 		}
364 		id.exp = vd.exp - VAX_DBL_BIAS + IEEE_DBL_BIAS;
365 		id.mantissa1 = (vd.mantissa1 << 13) | (vd.mantissa2 >> 3);
366 		id.mantissa2 = ((vd.mantissa2 & MASK(3)) << 29) |
367 				(vd.mantissa3 << 13) |
368 				((vd.mantissa4 >> 3) & MASK(13));
369 	shipit:
370 		id.sign = vd.sign;
371 		lp = (int32_t *)&id;
372 #else
373 		{
374 		/*
375 		 * Every machine can do this, its just not very efficient.
376 		 * In addtion, some rounding errors may occur do to the
377 		 * calculations involved.
378 		 */
379 		double d;
380 		int neg = 0;
381 		int exp = 0;
382 		int32_t val[2];
383 
384 		d = *dp;
385 		if (d == 0) {
386 			val[0] = 0;
387 			val[1] = 0;
388 			lp = val;
389 			return (XDR_PUTINT32(xdrs, lp++) &&
390 				XDR_PUTINT32(xdrs, lp));
391 		}
392 		if (d < 0) {
393 			d = 0 - d;
394 			neg = 1;
395 		}
396 		while (d < 1) {
397 			d = d * 2;
398 			--exp;
399 		}
400 		while (d >= 2) {
401 			d = d/2;
402 			++exp;
403 		}
404 		if ((exp > 1024) || (exp < -1023)) {
405 			/* over or under flowing ieee exponent */
406 			return (FALSE);
407 		}
408 		val[0] = neg;
409 		val[0] = val[0] << 11;	/* for the exponent */
410 		val[0] += 1023 + exp;	/* 1023 is the bias */
411 		val[0] = val[0] << 20;	/* for the mantissa */
412 		val[0] += (int32_t)((d - 1) * 1048576);	/* 2 ^ 20 */
413 		val[1] += (int32_t)((((d - 1) * 1048576) - val[0])
414 							* 4294967296);
415 		/* 2 ^ 32 */
416 		lp = val;
417 		}
418 #endif
419 		return (XDR_PUTINT32(xdrs, lp++) && XDR_PUTINT32(xdrs, lp));
420 #endif
421 #endif
422 
423 	case XDR_DECODE:
424 #if defined(mc68000) || defined(u3b2) || defined(u3b15) || \
425 	defined(_LONG_LONG_HTOL)
426 		lp = (int *)dp;
427 		return (XDR_GETINT32(xdrs, lp++) && XDR_GETINT32(xdrs, lp));
428 #else
429 #if defined(_LONG_LONG_LTOH)
430 		lp = (int *)dp;
431 		lp++;
432 		return (XDR_GETINT32(xdrs, lp--) && XDR_GETINT32(xdrs, lp));
433 #else
434 #if defined(vax)
435 		lp = (int32_t *)&id;
436 		if (!XDR_GETINT32(xdrs, lp++) || !XDR_GETINT32(xdrs, lp))
437 			return (FALSE);
438 		for (i = 0, lim = dbl_limits;
439 			i < sizeof (dbl_limits)/sizeof (struct dbl_limits);
440 			i++, lim++) {
441 			if ((id.mantissa2 == lim->ieee.mantissa2) &&
442 				(id.mantissa1 == lim->ieee.mantissa1) &&
443 				(id.exp == lim->ieee.exp)) {
444 				vd = lim->d;
445 				goto doneit;
446 			}
447 		}
448 		vd.exp = id.exp - IEEE_DBL_BIAS + VAX_DBL_BIAS;
449 		vd.mantissa1 = (id.mantissa1 >> 13);
450 		vd.mantissa2 = ((id.mantissa1 & MASK(13)) << 3) |
451 				(id.mantissa2 >> 29);
452 		vd.mantissa3 = (id.mantissa2 >> 13);
453 		vd.mantissa4 = (id.mantissa2 << 3);
454 	doneit:
455 		vd.sign = id.sign;
456 		*dp = *((double *)&vd);
457 		return (TRUE);
458 #else
459 		{
460 		/*
461 		 * Every machine can do this, its just not very
462 		 * efficient.  It assumes that the decoding machine's
463 		 * double can represent any value in the range of
464 		 *	ieee largest  double  = (2 ^ 1024)  * 0x1.fffffffffffff
465 		 *	to
466 		 *	ieee smallest double  = (2 ^ -1023) * 0x1.0000000000000
467 		 * In addtion, some rounding errors may occur do to the
468 		 * calculations involved.
469 		 */
470 		double d;
471 		int neg = 0;
472 		int exp = 0;
473 		int32_t val[2];
474 
475 		lp = val;
476 		if (!XDR_GETINT32(xdrs, lp++) || !XDR_GETINT32(xdrs, lp))
477 			return (FALSE);
478 		neg = val[0] & 0x80000000;
479 		exp = (val[0] & 0x7ff00000) >> 20;
480 		exp -= 1023;		/* subtract exponent base */
481 		d = (val[0] & 0x000fffff) * 0.00000095367431640625;
482 		/* 2 ^ -20 */
483 		d += (val[1] * 0.0000000000000002220446049250313);
484 		/* 2 ^ -52 */
485 		d++;
486 		while (exp != 0) {
487 			if (exp < 0) {
488 				d = d/2.0;
489 				++exp;
490 			} else {
491 				d = d * 2.0;
492 				--exp;
493 			}
494 		}
495 		if (neg)
496 			d = 0 - d;
497 		*dp = d;
498 		}
499 #endif
500 #endif
501 #endif
502 
503 	case XDR_FREE:
504 		return (TRUE);
505 	}
506 	return (FALSE);
507 }
508 
509 /* ARGSUSED */
510 bool_t
511 xdr_quadruple(XDR *xdrs, long double *fp)
512 {
513 /*
514  * The Sparc uses IEEE FP encoding, so just do a byte copy
515  */
516 
517 #if !defined(sparc)
518 	return (FALSE);
519 #else
520 	switch (xdrs->x_op) {
521 	case XDR_ENCODE:
522 		return (XDR_PUTBYTES(xdrs, (char *)fp, sizeof (long double)));
523 	case XDR_DECODE:
524 		return (XDR_GETBYTES(xdrs, (char *)fp, sizeof (long double)));
525 	case XDR_FREE:
526 		return (TRUE);
527 	}
528 	return (FALSE);
529 #endif
530 }
531