| Kyle Swenson | 8d8f654 | 2021-03-15 11:02:55 -0600 | [diff] [blame^] | 1 | /* IEEE754 floating point arithmetic |
| 2 | * single precision |
| 3 | */ |
| 4 | /* |
| 5 | * MIPS floating point support |
| 6 | * Copyright (C) 1994-2000 Algorithmics Ltd. |
| 7 | * |
| 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., |
| 19 | * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | */ |
| 21 | |
| 22 | #include "ieee754sp.h" |
| 23 | |
| 24 | int ieee754sp_tint(union ieee754sp x) |
| 25 | { |
| 26 | u32 residue; |
| 27 | int round; |
| 28 | int sticky; |
| 29 | int odd; |
| 30 | |
| 31 | COMPXSP; |
| 32 | |
| 33 | ieee754_clearcx(); |
| 34 | |
| 35 | EXPLODEXSP; |
| 36 | FLUSHXSP; |
| 37 | |
| 38 | switch (xc) { |
| 39 | case IEEE754_CLASS_SNAN: |
| 40 | case IEEE754_CLASS_QNAN: |
| 41 | case IEEE754_CLASS_INF: |
| 42 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
| 43 | return ieee754si_indef(); |
| 44 | |
| 45 | case IEEE754_CLASS_ZERO: |
| 46 | return 0; |
| 47 | |
| 48 | case IEEE754_CLASS_DNORM: |
| 49 | case IEEE754_CLASS_NORM: |
| 50 | break; |
| 51 | } |
| 52 | if (xe >= 31) { |
| 53 | /* look for valid corner case */ |
| 54 | if (xe == 31 && xs && xm == SP_HIDDEN_BIT) |
| 55 | return -0x80000000; |
| 56 | /* Set invalid. We will only use overflow for floating |
| 57 | point overflow */ |
| 58 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
| 59 | return ieee754si_indef(); |
| 60 | } |
| 61 | /* oh gawd */ |
| 62 | if (xe > SP_FBITS) { |
| 63 | xm <<= xe - SP_FBITS; |
| 64 | } else { |
| 65 | if (xe < -1) { |
| 66 | residue = xm; |
| 67 | round = 0; |
| 68 | sticky = residue != 0; |
| 69 | xm = 0; |
| 70 | } else { |
| 71 | /* Shifting a u32 32 times does not work, |
| 72 | * so we do it in two steps. Be aware that xe |
| 73 | * may be -1 */ |
| 74 | residue = xm << (xe + 1); |
| 75 | residue <<= 31 - SP_FBITS; |
| 76 | round = (residue >> 31) != 0; |
| 77 | sticky = (residue << 1) != 0; |
| 78 | xm >>= SP_FBITS - xe; |
| 79 | } |
| 80 | odd = (xm & 0x1) != 0x0; |
| 81 | switch (ieee754_csr.rm) { |
| 82 | case FPU_CSR_RN: |
| 83 | if (round && (sticky || odd)) |
| 84 | xm++; |
| 85 | break; |
| 86 | case FPU_CSR_RZ: |
| 87 | break; |
| 88 | case FPU_CSR_RU: /* toward +Infinity */ |
| 89 | if ((round || sticky) && !xs) |
| 90 | xm++; |
| 91 | break; |
| 92 | case FPU_CSR_RD: /* toward -Infinity */ |
| 93 | if ((round || sticky) && xs) |
| 94 | xm++; |
| 95 | break; |
| 96 | } |
| 97 | if ((xm >> 31) != 0) { |
| 98 | /* This can happen after rounding */ |
| 99 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
| 100 | return ieee754si_indef(); |
| 101 | } |
| 102 | if (round || sticky) |
| 103 | ieee754_setcx(IEEE754_INEXACT); |
| 104 | } |
| 105 | if (xs) |
| 106 | return -xm; |
| 107 | else |
| 108 | return xm; |
| 109 | } |