1 // SPDX-License-Identifier: GPL-2.0-only
2 /* IEEE754 floating point arithmetic
6 * MIPS floating point support
7 * Copyright (C) 1994-2000 Algorithmics Ltd.
10 #include "ieee754sp.h"
12 union ieee754sp ieee754sp_mul(union ieee754sp x, union ieee754sp y)
37 switch (CLPAIR(xc, yc)) {
38 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
39 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
40 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
41 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
42 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
43 return ieee754sp_nanxcpt(y);
45 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
46 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
47 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
48 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
49 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
50 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
51 return ieee754sp_nanxcpt(x);
53 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
54 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
55 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
56 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
59 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
60 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
61 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
62 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
63 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
70 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
71 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
72 ieee754_setcx(IEEE754_INVALID_OPERATION);
73 return ieee754sp_indef();
75 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
76 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
77 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
78 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
79 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
80 return ieee754sp_inf(xs ^ ys);
82 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
83 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
84 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
85 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
86 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
87 return ieee754sp_zero(xs ^ ys);
90 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
94 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
98 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
102 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
105 /* rm = xm * ym, re = xe+ye basically */
106 assert(xm & SP_HIDDEN_BIT);
107 assert(ym & SP_HIDDEN_BIT);
112 /* shunt to top of word */
113 xm <<= 32 - (SP_FBITS + 1);
114 ym <<= 32 - (SP_FBITS + 1);
117 * Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
124 lrm = lxm * lym; /* 16 * 16 => 32 */
125 hrm = hxm * hym; /* 16 * 16 => 32 */
127 t = lxm * hym; /* 16 * 16 => 32 */
128 at = lrm + (t << 16);
131 hrm = hrm + (t >> 16);
133 t = hxm * lym; /* 16 * 16 => 32 */
134 at = lrm + (t << 16);
137 hrm = hrm + (t >> 16);
139 rm = hrm | (lrm != 0);
142 * Sticky shift down to normal rounding precision.
145 rm = (rm >> (32 - (SP_FBITS + 1 + 3))) |
146 ((rm << (SP_FBITS + 1 + 3)) != 0);
149 rm = (rm >> (32 - (SP_FBITS + 1 + 3 + 1))) |
150 ((rm << (SP_FBITS + 1 + 3 + 1)) != 0);
152 assert(rm & (SP_HIDDEN_BIT << 3));
154 return ieee754sp_format(rs, re, rm);