1 /* IEEE754 floating point arithmetic 2 * single precision 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 "ieee754sp.h" 30 31 int ieee754sp_tint(ieee754sp x) 32 { 33 COMPXSP; 34 35 CLEARCX; 36 37 EXPLODEXSP; 38 FLUSHXSP; 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(), "sp_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 /* 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 SETCX(IEEE754_INVALID_OPERATION); 59 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x); 60 } 61 /* oh gawd */ 62 if (xe > SP_MBITS) { 63 xm <<= xe - SP_MBITS; 64 } else { 65 u32 residue; 66 int round; 67 int sticky; 68 int odd; 69 70 if (xe < -1) { 71 residue = xm; 72 round = 0; 73 sticky = residue != 0; 74 xm = 0; 75 } else { 76 /* Shifting a u32 32 times does not work, 77 * so we do it in two steps. Be aware that xe 78 * may be -1 */ 79 residue = xm << (xe + 1); 80 residue <<= 31 - SP_MBITS; 81 round = (residue >> 31) != 0; 82 sticky = (residue << 1) != 0; 83 xm >>= SP_MBITS - xe; 84 } 85 odd = (xm & 0x1) != 0x0; 86 switch (ieee754_csr.rm) { 87 case IEEE754_RN: 88 if (round && (sticky || odd)) 89 xm++; 90 break; 91 case IEEE754_RZ: 92 break; 93 case IEEE754_RU: /* toward +Infinity */ 94 if ((round || sticky) && !xs) 95 xm++; 96 break; 97 case IEEE754_RD: /* toward -Infinity */ 98 if ((round || sticky) && xs) 99 xm++; 100 break; 101 } 102 if ((xm >> 31) != 0) { 103 /* This can happen after rounding */ 104 SETCX(IEEE754_INVALID_OPERATION); 105 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x); 106 } 107 if (round || sticky) 108 SETCX(IEEE754_INEXACT); 109 } 110 if (xs) 111 return -xm; 112 else 113 return xm; 114 } 115 116 117 unsigned int ieee754sp_tuns(ieee754sp x) 118 { 119 ieee754sp hb = ieee754sp_1e31(); 120 121 /* what if x < 0 ?? */ 122 if (ieee754sp_lt(x, hb)) 123 return (unsigned) ieee754sp_tint(x); 124 125 return (unsigned) ieee754sp_tint(ieee754sp_sub(x, hb)) | 126 ((unsigned) 1 << 31); 127 } 128