1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * IEEE754 floating point arithmetic
4 * double precision: MIN{,A}.f
5 * MIN : Scalar Floating-Point Minimum
6 * MINA: Scalar Floating-Point argument with Minimum Absolute Value
7 *
8 * MIN.D : FPR[fd] = minNum(FPR[fs],FPR[ft])
9 * MINA.D: FPR[fd] = maxNumMag(FPR[fs],FPR[ft])
10 *
11 * MIPS floating point support
12 * Copyright (C) 2015 Imagination Technologies, Ltd.
13 * Author: Markos Chandras <markos.chandras@imgtec.com>
14 */
15
16#include "ieee754dp.h"
17
18union ieee754dp ieee754dp_fmin(union ieee754dp x, union ieee754dp y)
19{
20	COMPXDP;
21	COMPYDP;
22
23	EXPLODEXDP;
24	EXPLODEYDP;
25
26	FLUSHXDP;
27	FLUSHYDP;
28
29	ieee754_clearcx();
30
31	switch (CLPAIR(xc, yc)) {
32	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
33	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
34	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
35	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
36	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
37		return ieee754dp_nanxcpt(y);
38
39	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
40	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
41	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
42	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
43	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
44	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
45		return ieee754dp_nanxcpt(x);
46
47	/*
48	 * Quiet NaN handling
49	 */
50
51	/*
52	 *    The case of both inputs quiet NaNs
53	 */
54	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
55		return x;
56
57	/*
58	 *    The cases of exactly one input quiet NaN (numbers
59	 *    are here preferred as returned values to NaNs)
60	 */
61	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
62	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
63	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
64	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
65		return x;
66
67	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
68	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
69	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
70	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
71		return y;
72
73	/*
74	 * Infinity and zero handling
75	 */
76	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
77	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
78	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
79	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
80	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
81		return xs ? x : y;
82
83	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
84	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
85	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
86	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
87	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
88	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
89		return ys ? y : x;
90
91	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
92		return ieee754dp_zero(xs | ys);
93
94	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
95		DPDNORMX;
96		fallthrough;
97	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
98		DPDNORMY;
99		break;
100
101	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
102		DPDNORMX;
103	}
104
105	/* Finally get to do some computation */
106
107	assert(xm & DP_HIDDEN_BIT);
108	assert(ym & DP_HIDDEN_BIT);
109
110	/* Compare signs */
111	if (xs > ys)
112		return x;
113	else if (xs < ys)
114		return y;
115
116	/* Signs of inputs are the same, let's compare exponents */
117	if (xs == 0) {
118		/* Inputs are both positive */
119		if (xe > ye)
120			return y;
121		else if (xe < ye)
122			return x;
123	} else {
124		/* Inputs are both negative */
125		if (xe > ye)
126			return x;
127		else if (xe < ye)
128			return y;
129	}
130
131	/* Signs and exponents of inputs are equal, let's compare mantissas */
132	if (xs == 0) {
133		/* Inputs are both positive, with equal signs and exponents */
134		if (xm <= ym)
135			return x;
136		return y;
137	}
138	/* Inputs are both negative, with equal signs and exponents */
139	if (xm <= ym)
140		return y;
141	return x;
142}
143
144union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y)
145{
146	COMPXDP;
147	COMPYDP;
148
149	EXPLODEXDP;
150	EXPLODEYDP;
151
152	FLUSHXDP;
153	FLUSHYDP;
154
155	ieee754_clearcx();
156
157	switch (CLPAIR(xc, yc)) {
158	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
159	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
160	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
161	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
162	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
163		return ieee754dp_nanxcpt(y);
164
165	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
166	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
167	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
168	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
169	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
170	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
171		return ieee754dp_nanxcpt(x);
172
173	/*
174	 * Quiet NaN handling
175	 */
176
177	/*
178	 *    The case of both inputs quiet NaNs
179	 */
180	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
181		return x;
182
183	/*
184	 *    The cases of exactly one input quiet NaN (numbers
185	 *    are here preferred as returned values to NaNs)
186	 */
187	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
188	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
189	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
190	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
191		return x;
192
193	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
194	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
195	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
196	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
197		return y;
198
199	/*
200	 * Infinity and zero handling
201	 */
202	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
203		return ieee754dp_inf(xs | ys);
204
205	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
206	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
207	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
208	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
209	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
210		return y;
211
212	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
213	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
214	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
215	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
216	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
217		return x;
218
219	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
220		return ieee754dp_zero(xs | ys);
221
222	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
223		DPDNORMX;
224		fallthrough;
225	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
226		DPDNORMY;
227		break;
228
229	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
230		DPDNORMX;
231	}
232
233	/* Finally get to do some computation */
234
235	assert(xm & DP_HIDDEN_BIT);
236	assert(ym & DP_HIDDEN_BIT);
237
238	/* Compare exponent */
239	if (xe > ye)
240		return y;
241	else if (xe < ye)
242		return x;
243
244	/* Compare mantissa */
245	if (xm < ym)
246		return x;
247	else if (xm > ym)
248		return y;
249	else if (xs == 1)
250		return x;
251	return y;
252}
253