Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* IEEE754 floating point arithmetic |
| 2 | * single precision |
| 3 | */ |
| 4 | /* |
| 5 | * MIPS floating point support |
| 6 | * Copyright (C) 1994-2000 Algorithmics Ltd. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | * |
| 8 | * ######################################################################## |
| 9 | * |
| 10 | * This program is free software; you can distribute it and/or modify it |
| 11 | * under the terms of the GNU General Public License (Version 2) as |
| 12 | * published by the Free Software Foundation. |
| 13 | * |
| 14 | * This program is distributed in the hope it will be useful, but WITHOUT |
| 15 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 16 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 17 | * for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU General Public License along |
| 20 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 21 | * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. |
| 22 | * |
| 23 | * ######################################################################## |
| 24 | */ |
| 25 | |
Ralf Baechle | cae5506 | 2014-04-16 00:47:59 +0200 | [diff] [blame] | 26 | #include <linux/compiler.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | |
| 28 | #include "ieee754sp.h" |
| 29 | |
Ralf Baechle | 2209bcb | 2014-04-16 01:31:11 +0200 | [diff] [blame] | 30 | int ieee754sp_class(union ieee754sp x) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | { |
| 32 | COMPXSP; |
| 33 | EXPLODEXSP; |
| 34 | return xc; |
| 35 | } |
| 36 | |
Ralf Baechle | 2209bcb | 2014-04-16 01:31:11 +0200 | [diff] [blame] | 37 | int ieee754sp_isnan(union ieee754sp x) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | { |
| 39 | return ieee754sp_class(x) >= IEEE754_CLASS_SNAN; |
| 40 | } |
| 41 | |
Ralf Baechle | f71baa1 | 2014-04-25 00:40:42 +0200 | [diff] [blame] | 42 | static inline int ieee754sp_issnan(union ieee754sp x) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | { |
| 44 | assert(ieee754sp_isnan(x)); |
Ralf Baechle | ad8fb55 | 2014-04-22 15:51:55 +0200 | [diff] [blame] | 45 | return (SPMANT(x) & SP_MBIT(SP_FBITS-1)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | } |
| 47 | |
| 48 | |
Ralf Baechle | 90efba3 | 2014-04-25 03:19:57 +0200 | [diff] [blame^] | 49 | union ieee754sp __cold ieee754sp_nanxcpt(union ieee754sp r) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 50 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 51 | assert(ieee754sp_isnan(r)); |
| 52 | |
| 53 | if (!ieee754sp_issnan(r)) /* QNAN does not cause invalid op !! */ |
| 54 | return r; |
| 55 | |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 56 | if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | /* not enabled convert to a quiet NaN */ |
Ralf Baechle | ad8fb55 | 2014-04-22 15:51:55 +0200 | [diff] [blame] | 58 | SPMANT(r) &= (~SP_MBIT(SP_FBITS-1)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 59 | if (ieee754sp_isnan(r)) |
| 60 | return r; |
| 61 | else |
| 62 | return ieee754sp_indef(); |
| 63 | } |
| 64 | |
Ralf Baechle | 90efba3 | 2014-04-25 03:19:57 +0200 | [diff] [blame^] | 65 | return r; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 66 | } |
| 67 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | static unsigned get_rounding(int sn, unsigned xm) |
| 69 | { |
| 70 | /* inexact must round of 3 bits |
| 71 | */ |
| 72 | if (xm & (SP_MBIT(3) - 1)) { |
| 73 | switch (ieee754_csr.rm) { |
| 74 | case IEEE754_RZ: |
| 75 | break; |
| 76 | case IEEE754_RN: |
| 77 | xm += 0x3 + ((xm >> 3) & 1); |
| 78 | /* xm += (xm&0x8)?0x4:0x3 */ |
| 79 | break; |
| 80 | case IEEE754_RU: /* toward +Infinity */ |
| 81 | if (!sn) /* ?? */ |
| 82 | xm += 0x8; |
| 83 | break; |
| 84 | case IEEE754_RD: /* toward -Infinity */ |
Ralf Baechle | 7034228 | 2013-01-22 12:59:30 +0100 | [diff] [blame] | 85 | if (sn) /* ?? */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | */ |
Ralf Baechle | 2209bcb | 2014-04-16 01:31:11 +0200 | [diff] [blame] | 99 | union ieee754sp ieee754sp_format(int sn, int xe, unsigned xm) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 100 | { |
| 101 | assert(xm); /* we don't gen exact zeros (probably should) */ |
| 102 | |
Ralf Baechle | ad8fb55 | 2014-04-22 15:51:55 +0200 | [diff] [blame] | 103 | assert((xm >> (SP_FBITS + 1 + 3)) == 0); /* no execess */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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) { |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 111 | ieee754_setcx(IEEE754_UNDERFLOW); |
| 112 | ieee754_setcx(IEEE754_INEXACT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 113 | |
| 114 | switch(ieee754_csr.rm) { |
| 115 | case IEEE754_RN: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 116 | case IEEE754_RZ: |
| 117 | return ieee754sp_zero(sn); |
| 118 | case IEEE754_RU: /* toward +Infinity */ |
Ralf Baechle | 47fa0c0 | 2014-04-16 11:00:12 +0200 | [diff] [blame] | 119 | if (sn == 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 120 | return ieee754sp_min(0); |
| 121 | else |
| 122 | return ieee754sp_zero(1); |
| 123 | case IEEE754_RD: /* toward -Infinity */ |
Ralf Baechle | 47fa0c0 | 2014-04-16 11:00:12 +0200 | [diff] [blame] | 124 | if (sn == 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | return ieee754sp_zero(0); |
| 126 | else |
| 127 | return ieee754sp_min(1); |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | if (xe == SP_EMIN - 1 |
Ralf Baechle | ad8fb55 | 2014-04-22 15:51:55 +0200 | [diff] [blame] | 132 | && get_rounding(sn, xm) >> (SP_FBITS + 1 + 3)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | { |
| 134 | /* Not tiny after rounding */ |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 135 | ieee754_setcx(IEEE754_INEXACT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 136 | xm = get_rounding(sn, xm); |
| 137 | xm >>= 1; |
| 138 | /* Clear grs bits */ |
| 139 | xm &= ~(SP_MBIT(3) - 1); |
| 140 | xe++; |
Ralf Baechle | 47fa0c0 | 2014-04-16 11:00:12 +0200 | [diff] [blame] | 141 | } else { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 142 | /* sticky right shift es bits |
| 143 | */ |
| 144 | SPXSRSXn(es); |
| 145 | assert((xm & (SP_HIDDEN_BIT << 3)) == 0); |
| 146 | assert(xe == SP_EMIN); |
| 147 | } |
| 148 | } |
| 149 | if (xm & (SP_MBIT(3) - 1)) { |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 150 | ieee754_setcx(IEEE754_INEXACT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 151 | if ((xm & (SP_HIDDEN_BIT << 3)) == 0) { |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 152 | ieee754_setcx(IEEE754_UNDERFLOW); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 153 | } |
| 154 | |
| 155 | /* inexact must round of 3 bits |
| 156 | */ |
| 157 | xm = get_rounding(sn, xm); |
| 158 | /* adjust exponent for rounding add overflowing |
| 159 | */ |
Ralf Baechle | ad8fb55 | 2014-04-22 15:51:55 +0200 | [diff] [blame] | 160 | if (xm >> (SP_FBITS + 1 + 3)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 161 | /* add causes mantissa overflow */ |
| 162 | xm >>= 1; |
| 163 | xe++; |
| 164 | } |
| 165 | } |
| 166 | /* strip grs bits */ |
| 167 | xm >>= 3; |
| 168 | |
Ralf Baechle | ad8fb55 | 2014-04-22 15:51:55 +0200 | [diff] [blame] | 169 | assert((xm >> (SP_FBITS + 1)) == 0); /* no execess */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 170 | assert(xe >= SP_EMIN); |
| 171 | |
| 172 | if (xe > SP_EMAX) { |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 173 | ieee754_setcx(IEEE754_OVERFLOW); |
| 174 | ieee754_setcx(IEEE754_INEXACT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 175 | /* -O can be table indexed by (rm,sn) */ |
| 176 | switch (ieee754_csr.rm) { |
| 177 | case IEEE754_RN: |
| 178 | return ieee754sp_inf(sn); |
| 179 | case IEEE754_RZ: |
| 180 | return ieee754sp_max(sn); |
| 181 | case IEEE754_RU: /* toward +Infinity */ |
| 182 | if (sn == 0) |
| 183 | return ieee754sp_inf(0); |
| 184 | else |
| 185 | return ieee754sp_max(1); |
| 186 | case IEEE754_RD: /* toward -Infinity */ |
| 187 | if (sn == 0) |
| 188 | return ieee754sp_max(0); |
| 189 | else |
| 190 | return ieee754sp_inf(1); |
| 191 | } |
| 192 | } |
| 193 | /* gen norm/denorm/zero */ |
| 194 | |
| 195 | if ((xm & SP_HIDDEN_BIT) == 0) { |
| 196 | /* we underflow (tiny/zero) */ |
| 197 | assert(xe == SP_EMIN); |
| 198 | if (ieee754_csr.mx & IEEE754_UNDERFLOW) |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 199 | ieee754_setcx(IEEE754_UNDERFLOW); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 200 | return buildsp(sn, SP_EMIN - 1 + SP_EBIAS, xm); |
| 201 | } else { |
Ralf Baechle | ad8fb55 | 2014-04-22 15:51:55 +0200 | [diff] [blame] | 202 | assert((xm >> (SP_FBITS + 1)) == 0); /* no execess */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 203 | assert(xm & SP_HIDDEN_BIT); |
| 204 | |
| 205 | return buildsp(sn, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT); |
| 206 | } |
| 207 | } |