1 /* IEEE754 floating point arithmetic 2 * double precision: common utilities 3 */ 4 /* 5 * MIPS floating point support 6 * Copyright (C) 1994-2000 Algorithmics Ltd. 7 * http://www.algor.co.uk 8 * 9 * ######################################################################## 10 * 11 * This program is free software; you can distribute it and/or modify it 12 * under the terms of the GNU General Public License (Version 2) as 13 * published by the Free Software Foundation. 14 * 15 * This program is distributed in the hope it will be useful, but WITHOUT 16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 17 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 18 * for more details. 19 * 20 * You should have received a copy of the GNU General Public License along 21 * with this program; if not, write to the Free Software Foundation, Inc., 22 * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. 23 * 24 * ######################################################################## 25 */ 26 27 28 #include <linux/kernel.h> 29 #include "ieee754dp.h" 30 31 int ieee754dp_tint(ieee754dp x) 32 { 33 COMPXDP; 34 35 CLEARCX; 36 37 EXPLODEXDP; 38 FLUSHXDP; 39 40 switch (xc) { 41 case IEEE754_CLASS_SNAN: 42 case IEEE754_CLASS_QNAN: 43 case IEEE754_CLASS_INF: 44 SETCX(IEEE754_INVALID_OPERATION); 45 return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x); 46 case IEEE754_CLASS_ZERO: 47 return 0; 48 case IEEE754_CLASS_DNORM: 49 case IEEE754_CLASS_NORM: 50 break; 51 } 52 if (xe > 31) { 53 /* Set invalid. We will only use overflow for floating 54 point overflow */ 55 SETCX(IEEE754_INVALID_OPERATION); 56 return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x); 57 } 58 /* oh gawd */ 59 if (xe > DP_MBITS) { 60 xm <<= xe - DP_MBITS; 61 } else if (xe < DP_MBITS) { 62 u64 residue; 63 int round; 64 int sticky; 65 int odd; 66 67 if (xe < -1) { 68 residue = xm; 69 round = 0; 70 sticky = residue != 0; 71 xm = 0; 72 } else { 73 residue = xm << (64 - DP_MBITS + xe); 74 round = (residue >> 63) != 0; 75 sticky = (residue << 1) != 0; 76 xm >>= DP_MBITS - xe; 77 } 78 /* Note: At this point upper 32 bits of xm are guaranteed 79 to be zero */ 80 odd = (xm & 0x1) != 0x0; 81 switch (ieee754_csr.rm) { 82 case IEEE754_RN: 83 if (round && (sticky || odd)) 84 xm++; 85 break; 86 case IEEE754_RZ: 87 break; 88 case IEEE754_RU: /* toward +Infinity */ 89 if ((round || sticky) && !xs) 90 xm++; 91 break; 92 case IEEE754_RD: /* toward -Infinity */ 93 if ((round || sticky) && xs) 94 xm++; 95 break; 96 } 97 /* look for valid corner case 0x80000000 */ 98 if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) { 99 /* This can happen after rounding */ 100 SETCX(IEEE754_INVALID_OPERATION); 101 return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x); 102 } 103 if (round || sticky) 104 SETCX(IEEE754_INEXACT); 105 } 106 if (xs) 107 return -xm; 108 else 109 return xm; 110 } 111 112 113 unsigned int ieee754dp_tuns(ieee754dp x) 114 { 115 ieee754dp hb = ieee754dp_1e31(); 116 117 /* what if x < 0 ?? */ 118 if (ieee754dp_lt(x, hb)) 119 return (unsigned) ieee754dp_tint(x); 120 121 return (unsigned) ieee754dp_tint(ieee754dp_sub(x, hb)) | 122 ((unsigned) 1 << 31); 123 } 124