1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /* IEEE754 floating point arithmetic
3*4882a593Smuzhiyun * double precision: common utilities
4*4882a593Smuzhiyun */
5*4882a593Smuzhiyun /*
6*4882a593Smuzhiyun * MIPS floating point support
7*4882a593Smuzhiyun * Copyright (C) 1994-2000 Algorithmics Ltd.
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #include "ieee754dp.h"
11*4882a593Smuzhiyun
ieee754dp_div(union ieee754dp x,union ieee754dp y)12*4882a593Smuzhiyun union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y)
13*4882a593Smuzhiyun {
14*4882a593Smuzhiyun u64 rm;
15*4882a593Smuzhiyun int re;
16*4882a593Smuzhiyun u64 bm;
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun COMPXDP;
19*4882a593Smuzhiyun COMPYDP;
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun EXPLODEXDP;
22*4882a593Smuzhiyun EXPLODEYDP;
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun ieee754_clearcx();
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun FLUSHXDP;
27*4882a593Smuzhiyun FLUSHYDP;
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun switch (CLPAIR(xc, yc)) {
30*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
31*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
32*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
33*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
34*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
35*4882a593Smuzhiyun return ieee754dp_nanxcpt(y);
36*4882a593Smuzhiyun
37*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
38*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
39*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
40*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
41*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
42*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
43*4882a593Smuzhiyun return ieee754dp_nanxcpt(x);
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
46*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
47*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
48*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
49*4882a593Smuzhiyun return y;
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
52*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
53*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
54*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
55*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
56*4882a593Smuzhiyun return x;
57*4882a593Smuzhiyun
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun /*
60*4882a593Smuzhiyun * Infinity handling
61*4882a593Smuzhiyun */
62*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
63*4882a593Smuzhiyun ieee754_setcx(IEEE754_INVALID_OPERATION);
64*4882a593Smuzhiyun return ieee754dp_indef();
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
67*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
68*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
69*4882a593Smuzhiyun return ieee754dp_zero(xs ^ ys);
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
72*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
73*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
74*4882a593Smuzhiyun return ieee754dp_inf(xs ^ ys);
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun /*
77*4882a593Smuzhiyun * Zero handling
78*4882a593Smuzhiyun */
79*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
80*4882a593Smuzhiyun ieee754_setcx(IEEE754_INVALID_OPERATION);
81*4882a593Smuzhiyun return ieee754dp_indef();
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
84*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
85*4882a593Smuzhiyun ieee754_setcx(IEEE754_ZERO_DIVIDE);
86*4882a593Smuzhiyun return ieee754dp_inf(xs ^ ys);
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
89*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
90*4882a593Smuzhiyun return ieee754dp_zero(xs == ys ? 0 : 1);
91*4882a593Smuzhiyun
92*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
93*4882a593Smuzhiyun DPDNORMX;
94*4882a593Smuzhiyun fallthrough;
95*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
96*4882a593Smuzhiyun DPDNORMY;
97*4882a593Smuzhiyun break;
98*4882a593Smuzhiyun
99*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
100*4882a593Smuzhiyun DPDNORMX;
101*4882a593Smuzhiyun break;
102*4882a593Smuzhiyun
103*4882a593Smuzhiyun case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
104*4882a593Smuzhiyun break;
105*4882a593Smuzhiyun }
106*4882a593Smuzhiyun assert(xm & DP_HIDDEN_BIT);
107*4882a593Smuzhiyun assert(ym & DP_HIDDEN_BIT);
108*4882a593Smuzhiyun
109*4882a593Smuzhiyun /* provide rounding space */
110*4882a593Smuzhiyun xm <<= 3;
111*4882a593Smuzhiyun ym <<= 3;
112*4882a593Smuzhiyun
113*4882a593Smuzhiyun /* now the dirty work */
114*4882a593Smuzhiyun
115*4882a593Smuzhiyun rm = 0;
116*4882a593Smuzhiyun re = xe - ye;
117*4882a593Smuzhiyun
118*4882a593Smuzhiyun for (bm = DP_MBIT(DP_FBITS + 2); bm; bm >>= 1) {
119*4882a593Smuzhiyun if (xm >= ym) {
120*4882a593Smuzhiyun xm -= ym;
121*4882a593Smuzhiyun rm |= bm;
122*4882a593Smuzhiyun if (xm == 0)
123*4882a593Smuzhiyun break;
124*4882a593Smuzhiyun }
125*4882a593Smuzhiyun xm <<= 1;
126*4882a593Smuzhiyun }
127*4882a593Smuzhiyun
128*4882a593Smuzhiyun rm <<= 1;
129*4882a593Smuzhiyun if (xm)
130*4882a593Smuzhiyun rm |= 1; /* have remainder, set sticky */
131*4882a593Smuzhiyun
132*4882a593Smuzhiyun assert(rm);
133*4882a593Smuzhiyun
134*4882a593Smuzhiyun /*
135*4882a593Smuzhiyun * Normalise rm to rounding precision ?
136*4882a593Smuzhiyun */
137*4882a593Smuzhiyun while ((rm >> (DP_FBITS + 3)) == 0) {
138*4882a593Smuzhiyun rm <<= 1;
139*4882a593Smuzhiyun re--;
140*4882a593Smuzhiyun }
141*4882a593Smuzhiyun
142*4882a593Smuzhiyun return ieee754dp_format(xs == ys ? 0 : 1, re, rm);
143*4882a593Smuzhiyun }
144