1/*
2 * IEEE754 floating point arithmetic
3 * single precision: MAX{,A}.f
4 * MAX : Scalar Floating-Point Maximum
5 * MAXA: Scalar Floating-Point argument with Maximum Absolute Value
6 *
7 * MAX.S : FPR[fd] = maxNum(FPR[fs],FPR[ft])
8 * MAXA.S: FPR[fd] = maxNumMag(FPR[fs],FPR[ft])
9 *
10 * MIPS floating point support
11 * Copyright (C) 2015 Imagination Technologies, Ltd.
12 * Author: Markos Chandras <markos.chandras@imgtec.com>
13 *
14 *  This program is free software; you can distribute it and/or modify it
15 *  under the terms of the GNU General Public License as published by the
16 *  Free Software Foundation; version 2 of the License.
17 */
18
19#include "ieee754sp.h"
20
21union ieee754sp ieee754sp_fmax(union ieee754sp x, union ieee754sp y)
22{
23	COMPXSP;
24	COMPYSP;
25
26	EXPLODEXSP;
27	EXPLODEYSP;
28
29	FLUSHXSP;
30	FLUSHYSP;
31
32	ieee754_clearcx();
33
34	switch (CLPAIR(xc, yc)) {
35	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
36	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
37	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
38	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
39	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
40		return ieee754sp_nanxcpt(y);
41
42	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
43	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
44	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
45	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
46	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
47	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
48		return ieee754sp_nanxcpt(x);
49
50	/* numbers are preferred to NaNs */
51	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
52	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
53	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
54	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
55		return x;
56
57	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
58	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
59	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
60	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
61	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
62		return y;
63
64	/*
65	 * Infinity and zero handling
66	 */
67	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
68	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
69	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
70	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
71	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
72		return xs ? y : x;
73
74	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
75	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
76	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
77	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
78	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
79	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
80		return ys ? x : y;
81
82	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
83		if (xs == ys)
84			return x;
85		return ieee754sp_zero(1);
86
87	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
88		SPDNORMX;
89
90	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
91		SPDNORMY;
92		break;
93
94	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
95		SPDNORMX;
96	}
97
98	/* Finally get to do some computation */
99
100	assert(xm & SP_HIDDEN_BIT);
101	assert(ym & SP_HIDDEN_BIT);
102
103	/* Compare signs */
104	if (xs > ys)
105		return y;
106	else if (xs < ys)
107		return x;
108
109	/* Compare exponent */
110	if (xe > ye)
111		return x;
112	else if (xe < ye)
113		return y;
114
115	/* Compare mantissa */
116	if (xm <= ym)
117		return y;
118	return x;
119}
120
121union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
122{
123	COMPXSP;
124	COMPYSP;
125
126	EXPLODEXSP;
127	EXPLODEYSP;
128
129	FLUSHXSP;
130	FLUSHYSP;
131
132	ieee754_clearcx();
133
134	switch (CLPAIR(xc, yc)) {
135	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
136	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
137	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
138	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
139	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
140		return ieee754sp_nanxcpt(y);
141
142	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
143	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
144	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
145	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
146	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
147	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
148		return ieee754sp_nanxcpt(x);
149
150	/* numbers are preferred to NaNs */
151	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
152	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
153	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
154	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
155		return x;
156
157	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
158	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
159	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
160	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
161	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
162		return y;
163
164	/*
165	 * Infinity and zero handling
166	 */
167	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
168	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
169	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
170	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
171	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
172		return x;
173
174	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
175	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
176	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
177	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
178	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
179	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
180		return y;
181
182	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
183		if (xs == ys)
184			return x;
185		return ieee754sp_zero(1);
186
187	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
188		SPDNORMX;
189
190	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
191		SPDNORMY;
192		break;
193
194	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
195		SPDNORMX;
196	}
197
198	/* Finally get to do some computation */
199
200	assert(xm & SP_HIDDEN_BIT);
201	assert(ym & SP_HIDDEN_BIT);
202
203	/* Compare exponent */
204	if (xe > ye)
205		return x;
206	else if (xe < ye)
207		return y;
208
209	/* Compare mantissa */
210	if (xm <= ym)
211		return y;
212	return x;
213}
214