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Commit | Line | Data |
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1da177e4 LT |
1 | /* IEEE754 floating point arithmetic |
2 | * single precision | |
3 | */ | |
4 | /* | |
5 | * MIPS floating point support | |
6 | * Copyright (C) 1994-2000 Algorithmics Ltd. | |
1da177e4 | 7 | * |
1da177e4 LT |
8 | * This program is free software; you can distribute it and/or modify it |
9 | * under the terms of the GNU General Public License (Version 2) as | |
10 | * published by the Free Software Foundation. | |
11 | * | |
12 | * This program is distributed in the hope it will be useful, but WITHOUT | |
13 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | * for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License along | |
18 | * with this program; if not, write to the Free Software Foundation, Inc., | |
3f7cac41 | 19 | * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
1da177e4 LT |
20 | */ |
21 | ||
cae55066 | 22 | #include <linux/compiler.h> |
1da177e4 LT |
23 | |
24 | #include "ieee754sp.h" | |
25 | ||
2209bcb1 | 26 | int ieee754sp_class(union ieee754sp x) |
1da177e4 LT |
27 | { |
28 | COMPXSP; | |
29 | EXPLODEXSP; | |
30 | return xc; | |
31 | } | |
32 | ||
e06b530b | 33 | static inline int ieee754sp_isnan(union ieee754sp x) |
1da177e4 | 34 | { |
c9a10845 | 35 | return ieee754_class_nan(ieee754sp_class(x)); |
1da177e4 LT |
36 | } |
37 | ||
f71baa11 | 38 | static inline int ieee754sp_issnan(union ieee754sp x) |
1da177e4 | 39 | { |
90d53a91 MR |
40 | int qbit; |
41 | ||
1da177e4 | 42 | assert(ieee754sp_isnan(x)); |
90d53a91 MR |
43 | qbit = (SPMANT(x) & SP_MBIT(SP_FBITS - 1)) == SP_MBIT(SP_FBITS - 1); |
44 | return ieee754_csr.nan2008 ^ qbit; | |
1da177e4 LT |
45 | } |
46 | ||
47 | ||
d5afa7e9 MR |
48 | /* |
49 | * Raise the Invalid Operation IEEE 754 exception | |
50 | * and convert the signaling NaN supplied to a quiet NaN. | |
51 | */ | |
90efba36 | 52 | union ieee754sp __cold ieee754sp_nanxcpt(union ieee754sp r) |
1da177e4 | 53 | { |
d5afa7e9 | 54 | assert(ieee754sp_issnan(r)); |
1da177e4 | 55 | |
d5afa7e9 | 56 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
acd9e20c | 57 | if (ieee754_csr.nan2008) { |
90d53a91 | 58 | SPMANT(r) |= SP_MBIT(SP_FBITS - 1); |
acd9e20c MR |
59 | } else { |
60 | SPMANT(r) &= ~SP_MBIT(SP_FBITS - 1); | |
61 | if (!ieee754sp_isnan(r)) | |
62 | SPMANT(r) |= SP_MBIT(SP_FBITS - 2); | |
63 | } | |
90d53a91 MR |
64 | |
65 | return r; | |
1da177e4 LT |
66 | } |
67 | ||
de2fc342 | 68 | static unsigned ieee754sp_get_rounding(int sn, unsigned xm) |
1da177e4 LT |
69 | { |
70 | /* inexact must round of 3 bits | |
71 | */ | |
72 | if (xm & (SP_MBIT(3) - 1)) { | |
73 | switch (ieee754_csr.rm) { | |
56a64733 | 74 | case FPU_CSR_RZ: |
1da177e4 | 75 | break; |
56a64733 | 76 | case FPU_CSR_RN: |
1da177e4 LT |
77 | xm += 0x3 + ((xm >> 3) & 1); |
78 | /* xm += (xm&0x8)?0x4:0x3 */ | |
79 | break; | |
56a64733 | 80 | case FPU_CSR_RU: /* toward +Infinity */ |
1da177e4 LT |
81 | if (!sn) /* ?? */ |
82 | xm += 0x8; | |
83 | break; | |
56a64733 | 84 | case FPU_CSR_RD: /* toward -Infinity */ |
70342287 | 85 | if (sn) /* ?? */ |
1da177e4 LT |
86 | xm += 0x8; |
87 | break; | |
88 | } | |
89 | } | |
90 | return xm; | |
91 | } | |
92 | ||
93 | ||
94 | /* generate a normal/denormal number with over,under handling | |
95 | * sn is sign | |
96 | * xe is an unbiased exponent | |
97 | * xm is 3bit extended precision value. | |
98 | */ | |
2209bcb1 | 99 | union ieee754sp ieee754sp_format(int sn, int xe, unsigned xm) |
1da177e4 LT |
100 | { |
101 | assert(xm); /* we don't gen exact zeros (probably should) */ | |
102 | ||
92a76f6d | 103 | assert((xm >> (SP_FBITS + 1 + 3)) == 0); /* no excess */ |
1da177e4 LT |
104 | assert(xm & (SP_HIDDEN_BIT << 3)); |
105 | ||
106 | if (xe < SP_EMIN) { | |
107 | /* strip lower bits */ | |
108 | int es = SP_EMIN - xe; | |
109 | ||
110 | if (ieee754_csr.nod) { | |
9e8bad1f RB |
111 | ieee754_setcx(IEEE754_UNDERFLOW); |
112 | ieee754_setcx(IEEE754_INEXACT); | |
1da177e4 LT |
113 | |
114 | switch(ieee754_csr.rm) { | |
56a64733 RB |
115 | case FPU_CSR_RN: |
116 | case FPU_CSR_RZ: | |
1da177e4 | 117 | return ieee754sp_zero(sn); |
56a64733 | 118 | case FPU_CSR_RU: /* toward +Infinity */ |
47fa0c02 | 119 | if (sn == 0) |
1da177e4 LT |
120 | return ieee754sp_min(0); |
121 | else | |
122 | return ieee754sp_zero(1); | |
56a64733 | 123 | case FPU_CSR_RD: /* toward -Infinity */ |
47fa0c02 | 124 | if (sn == 0) |
1da177e4 LT |
125 | return ieee754sp_zero(0); |
126 | else | |
127 | return ieee754sp_min(1); | |
128 | } | |
129 | } | |
130 | ||
de2fc342 RB |
131 | if (xe == SP_EMIN - 1 && |
132 | ieee754sp_get_rounding(sn, xm) >> (SP_FBITS + 1 + 3)) | |
1da177e4 LT |
133 | { |
134 | /* Not tiny after rounding */ | |
9e8bad1f | 135 | ieee754_setcx(IEEE754_INEXACT); |
de2fc342 | 136 | xm = ieee754sp_get_rounding(sn, xm); |
1da177e4 LT |
137 | xm >>= 1; |
138 | /* Clear grs bits */ | |
139 | xm &= ~(SP_MBIT(3) - 1); | |
140 | xe++; | |
47fa0c02 | 141 | } else { |
1da177e4 LT |
142 | /* sticky right shift es bits |
143 | */ | |
db57f29d PB |
144 | xm = XSPSRS(xm, es); |
145 | xe += es; | |
1da177e4 LT |
146 | assert((xm & (SP_HIDDEN_BIT << 3)) == 0); |
147 | assert(xe == SP_EMIN); | |
148 | } | |
149 | } | |
150 | if (xm & (SP_MBIT(3) - 1)) { | |
9e8bad1f | 151 | ieee754_setcx(IEEE754_INEXACT); |
1da177e4 | 152 | if ((xm & (SP_HIDDEN_BIT << 3)) == 0) { |
9e8bad1f | 153 | ieee754_setcx(IEEE754_UNDERFLOW); |
1da177e4 LT |
154 | } |
155 | ||
156 | /* inexact must round of 3 bits | |
157 | */ | |
de2fc342 | 158 | xm = ieee754sp_get_rounding(sn, xm); |
1da177e4 LT |
159 | /* adjust exponent for rounding add overflowing |
160 | */ | |
ad8fb553 | 161 | if (xm >> (SP_FBITS + 1 + 3)) { |
1da177e4 LT |
162 | /* add causes mantissa overflow */ |
163 | xm >>= 1; | |
164 | xe++; | |
165 | } | |
166 | } | |
167 | /* strip grs bits */ | |
168 | xm >>= 3; | |
169 | ||
92a76f6d | 170 | assert((xm >> (SP_FBITS + 1)) == 0); /* no excess */ |
1da177e4 LT |
171 | assert(xe >= SP_EMIN); |
172 | ||
173 | if (xe > SP_EMAX) { | |
9e8bad1f RB |
174 | ieee754_setcx(IEEE754_OVERFLOW); |
175 | ieee754_setcx(IEEE754_INEXACT); | |
1da177e4 LT |
176 | /* -O can be table indexed by (rm,sn) */ |
177 | switch (ieee754_csr.rm) { | |
56a64733 | 178 | case FPU_CSR_RN: |
1da177e4 | 179 | return ieee754sp_inf(sn); |
56a64733 | 180 | case FPU_CSR_RZ: |
1da177e4 | 181 | return ieee754sp_max(sn); |
56a64733 | 182 | case FPU_CSR_RU: /* toward +Infinity */ |
1da177e4 LT |
183 | if (sn == 0) |
184 | return ieee754sp_inf(0); | |
185 | else | |
186 | return ieee754sp_max(1); | |
56a64733 | 187 | case FPU_CSR_RD: /* toward -Infinity */ |
1da177e4 LT |
188 | if (sn == 0) |
189 | return ieee754sp_max(0); | |
190 | else | |
191 | return ieee754sp_inf(1); | |
192 | } | |
193 | } | |
194 | /* gen norm/denorm/zero */ | |
195 | ||
196 | if ((xm & SP_HIDDEN_BIT) == 0) { | |
197 | /* we underflow (tiny/zero) */ | |
198 | assert(xe == SP_EMIN); | |
199 | if (ieee754_csr.mx & IEEE754_UNDERFLOW) | |
9e8bad1f | 200 | ieee754_setcx(IEEE754_UNDERFLOW); |
1da177e4 LT |
201 | return buildsp(sn, SP_EMIN - 1 + SP_EBIAS, xm); |
202 | } else { | |
92a76f6d | 203 | assert((xm >> (SP_FBITS + 1)) == 0); /* no excess */ |
1da177e4 LT |
204 | assert(xm & SP_HIDDEN_BIT); |
205 | ||
206 | return buildsp(sn, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT); | |
207 | } | |
208 | } |