1/* IEEE754 floating point arithmetic
2 * double precision: common utilities
3 */
4/*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
7 * http://www.algor.co.uk
8 *
9 * ########################################################################
10 *
11 *  This program is free software; you can distribute it and/or modify it
12 *  under the terms of the GNU General Public License (Version 2) as
13 *  published by the Free Software Foundation.
14 *
15 *  This program is distributed in the hope it will be useful, but WITHOUT
16 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
17 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
18 *  for more details.
19 *
20 *  You should have received a copy of the GNU General Public License along
21 *  with this program; if not, write to the Free Software Foundation, Inc.,
22 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
23 *
24 * ########################################################################
25 */
26
27
28#include <linux/kernel.h>
29#include "ieee754dp.h"
30
31int ieee754dp_tint(ieee754dp x)
32{
33	COMPXDP;
34
35	CLEARCX;
36
37	EXPLODEXDP;
38	FLUSHXDP;
39
40	switch (xc) {
41	case IEEE754_CLASS_SNAN:
42	case IEEE754_CLASS_QNAN:
43	case IEEE754_CLASS_INF:
44		SETCX(IEEE754_INVALID_OPERATION);
45		return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
46	case IEEE754_CLASS_ZERO:
47		return 0;
48	case IEEE754_CLASS_DNORM:
49	case IEEE754_CLASS_NORM:
50		break;
51	}
52	if (xe > 31) {
53		/* Set invalid. We will only use overflow for floating
54		   point overflow */
55		SETCX(IEEE754_INVALID_OPERATION);
56		return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
57	}
58	/* oh gawd */
59	if (xe > DP_MBITS) {
60		xm <<= xe - DP_MBITS;
61	} else if (xe < DP_MBITS) {
62		u64 residue;
63		int round;
64		int sticky;
65		int odd;
66
67		if (xe < -1) {
68			residue = xm;
69			round = 0;
70			sticky = residue != 0;
71			xm = 0;
72		}
73		else {
74			residue = xm << (64 - DP_MBITS + xe);
75			round = (residue >> 63) != 0;
76			sticky = (residue << 1) != 0;
77			xm >>= DP_MBITS - xe;
78		}
79		/* Note: At this point upper 32 bits of xm are guaranteed
80		   to be zero */
81		odd = (xm & 0x1) != 0x0;
82		switch (ieee754_csr.rm) {
83		case IEEE754_RN:
84			if (round && (sticky || odd))
85				xm++;
86			break;
87		case IEEE754_RZ:
88			break;
89		case IEEE754_RU:	/* toward +Infinity */
90			if ((round || sticky) && !xs)
91				xm++;
92			break;
93		case IEEE754_RD:	/* toward -Infinity */
94			if ((round || sticky) && xs)
95				xm++;
96			break;
97		}
98		/* look for valid corner case 0x80000000 */
99		if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
100			/* This can happen after rounding */
101			SETCX(IEEE754_INVALID_OPERATION);
102			return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
103		}
104		if (round || sticky)
105			SETCX(IEEE754_INEXACT);
106	}
107	if (xs)
108		return -xm;
109	else
110		return xm;
111}
112
113
114unsigned int ieee754dp_tuns(ieee754dp x)
115{
116	ieee754dp hb = ieee754dp_1e31();
117
118	/* what if x < 0 ?? */
119	if (ieee754dp_lt(x, hb))
120		return (unsigned) ieee754dp_tint(x);
121
122	return (unsigned) ieee754dp_tint(ieee754dp_sub(x, hb)) |
123	    ((unsigned) 1 << 31);
124}
125