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 "ieee754dp.h"
29
30s64 ieee754dp_tlong(ieee754dp x)
31{
32	COMPXDP;
33
34	CLEARCX;
35
36	EXPLODEXDP;
37	FLUSHXDP;
38
39	switch (xc) {
40	case IEEE754_CLASS_SNAN:
41	case IEEE754_CLASS_QNAN:
42	case IEEE754_CLASS_INF:
43		SETCX(IEEE754_INVALID_OPERATION);
44		return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x);
45	case IEEE754_CLASS_ZERO:
46		return 0;
47	case IEEE754_CLASS_DNORM:
48	case IEEE754_CLASS_NORM:
49		break;
50	}
51	if (xe >= 63) {
52		/* look for valid corner case */
53		if (xe == 63 && xs && xm == DP_HIDDEN_BIT)
54			return -0x8000000000000000LL;
55		/* Set invalid. We will only use overflow for floating
56		   point overflow */
57		SETCX(IEEE754_INVALID_OPERATION);
58		return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x);
59	}
60	/* oh gawd */
61	if (xe > DP_MBITS) {
62		xm <<= xe - DP_MBITS;
63	} else if (xe < DP_MBITS) {
64		u64 residue;
65		int round;
66		int sticky;
67		int odd;
68
69		if (xe < -1) {
70			residue = xm;
71			round = 0;
72			sticky = residue != 0;
73			xm = 0;
74		}
75		else {
76			/* Shifting a u64 64 times does not work,
77			* so we do it in two steps. Be aware that xe
78			* may be -1 */
79			residue = xm << (xe + 1);
80			residue <<= 63 - DP_MBITS;
81			round = (residue >> 63) != 0;
82			sticky = (residue << 1) != 0;
83			xm >>= DP_MBITS - xe;
84		}
85		odd = (xm & 0x1) != 0x0;
86		switch (ieee754_csr.rm) {
87		case IEEE754_RN:
88			if (round && (sticky || odd))
89				xm++;
90			break;
91		case IEEE754_RZ:
92			break;
93		case IEEE754_RU:	/* toward +Infinity */
94			if ((round || sticky) && !xs)
95				xm++;
96			break;
97		case IEEE754_RD:	/* toward -Infinity */
98			if ((round || sticky) && xs)
99				xm++;
100			break;
101		}
102		if ((xm >> 63) != 0) {
103			/* This can happen after rounding */
104			SETCX(IEEE754_INVALID_OPERATION);
105			return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x);
106		}
107		if (round || sticky)
108			SETCX(IEEE754_INEXACT);
109	}
110	if (xs)
111		return -xm;
112	else
113		return xm;
114}
115
116
117u64 ieee754dp_tulong(ieee754dp x)
118{
119	ieee754dp hb = ieee754dp_1e63();
120
121	/* what if x < 0 ?? */
122	if (ieee754dp_lt(x, hb))
123		return (u64) ieee754dp_tlong(x);
124
125	return (u64) ieee754dp_tlong(ieee754dp_sub(x, hb)) |
126	    (1ULL << 63);
127}
128