1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * IEEE754 floating point arithmetic
4 * single precision: MAX{,A}.f
5 * MAX : Scalar Floating-Point Maximum
6 * MAXA: Scalar Floating-Point argument with Maximum Absolute Value
7 *
8 * MAX.S : FPR[fd] = maxNum(FPR[fs],FPR[ft])
9 * MAXA.S: 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 "ieee754sp.h"
17
18 union ieee754sp ieee754sp_fmax(union ieee754sp x, union ieee754sp y)
19 {
20 COMPXSP;
21 COMPYSP;
22
23 EXPLODEXSP;
24 EXPLODEYSP;
25
26 FLUSHXSP;
27 FLUSHYSP;
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 ieee754sp_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 ieee754sp_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 ? y : x;
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 ? x : y;
90
91 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
92 return ieee754sp_zero(xs & ys);
93
94 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
95 SPDNORMX;
96 fallthrough;
97 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
98 SPDNORMY;
99 break;
100
101 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
102 SPDNORMX;
103 }
104
105 /* Finally get to do some computation */
106
107 assert(xm & SP_HIDDEN_BIT);
108 assert(ym & SP_HIDDEN_BIT);
109
110 /* Compare signs */
111 if (xs > ys)
112 return y;
113 else if (xs < ys)
114 return x;
115
116 /* Signs of inputs are equal, let's compare exponents */
117 if (xs == 0) {
118 /* Inputs are both positive */
119 if (xe > ye)
120 return x;
121 else if (xe < ye)
122 return y;
123 } else {
124 /* Inputs are both negative */
125 if (xe > ye)
126 return y;
127 else if (xe < ye)
128 return x;
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 y;
136 return x;
137 }
138 /* Inputs are both negative, with equal signs and exponents */
139 if (xm <= ym)
140 return x;
141 return y;
142 }
143
144 union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
145 {
146 COMPXSP;
147 COMPYSP;
148
149 EXPLODEXSP;
150 EXPLODEYSP;
151
152 FLUSHXSP;
153 FLUSHYSP;
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 ieee754sp_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 ieee754sp_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 ieee754sp_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 x;
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 y;
218
219 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
220 return ieee754sp_zero(xs & ys);
221
222 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
223 SPDNORMX;
224 fallthrough;
225 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
226 SPDNORMY;
227 break;
228
229 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
230 SPDNORMX;
231 }
232
233 /* Finally get to do some computation */
234
235 assert(xm & SP_HIDDEN_BIT);
236 assert(ym & SP_HIDDEN_BIT);
237
238 /* Compare exponent */
239 if (xe > ye)
240 return x;
241 else if (xe < ye)
242 return y;
243
244 /* Compare mantissa */
245 if (xm < ym)
246 return y;
247 else if (xm > ym)
248 return x;
249 else if (xs == 0)
250 return x;
251 return y;
252 }
253
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