1 /* IEEE754 floating point arithmetic 2 * single precision 3 */ 4 /* 5 * MIPS floating point support 6 * Copyright (C) 1994-2000 Algorithmics Ltd. 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 26 27 #include <linux/kernel.h> 28 #include "ieee754sp.h" 29 30 int ieee754sp_tint(ieee754sp x) 31 { 32 COMPXSP; 33 34 CLEARCX; 35 36 EXPLODEXSP; 37 FLUSHXSP; 38 39 switch (xc) { 40 case IEEE754_CLASS_SNAN: 41 case IEEE754_CLASS_QNAN: 42 case IEEE754_CLASS_INF: 43 SETCX(IEEE754_INVALID_OPERATION); 44 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x); 45 case IEEE754_CLASS_ZERO: 46 return 0; 47 case IEEE754_CLASS_DNORM: 48 case IEEE754_CLASS_NORM: 49 break; 50 } 51 if (xe >= 31) { 52 /* look for valid corner case */ 53 if (xe == 31 && xs && xm == SP_HIDDEN_BIT) 54 return -0x80000000; 55 /* Set invalid. We will only use overflow for floating 56 point overflow */ 57 SETCX(IEEE754_INVALID_OPERATION); 58 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x); 59 } 60 /* oh gawd */ 61 if (xe > SP_MBITS) { 62 xm <<= xe - SP_MBITS; 63 } else { 64 u32 residue; 65 int round; 66 int sticky; 67 int odd; 68 69 if (xe < -1) { 70 residue = xm; 71 round = 0; 72 sticky = residue != 0; 73 xm = 0; 74 } else { 75 /* Shifting a u32 32 times does not work, 76 * so we do it in two steps. Be aware that xe 77 * may be -1 */ 78 residue = xm << (xe + 1); 79 residue <<= 31 - SP_MBITS; 80 round = (residue >> 31) != 0; 81 sticky = (residue << 1) != 0; 82 xm >>= SP_MBITS - xe; 83 } 84 odd = (xm & 0x1) != 0x0; 85 switch (ieee754_csr.rm) { 86 case IEEE754_RN: 87 if (round && (sticky || odd)) 88 xm++; 89 break; 90 case IEEE754_RZ: 91 break; 92 case IEEE754_RU: /* toward +Infinity */ 93 if ((round || sticky) && !xs) 94 xm++; 95 break; 96 case IEEE754_RD: /* toward -Infinity */ 97 if ((round || sticky) && xs) 98 xm++; 99 break; 100 } 101 if ((xm >> 31) != 0) { 102 /* This can happen after rounding */ 103 SETCX(IEEE754_INVALID_OPERATION); 104 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x); 105 } 106 if (round || sticky) 107 SETCX(IEEE754_INEXACT); 108 } 109 if (xs) 110 return -xm; 111 else 112 return xm; 113 } 114 115 116 unsigned int ieee754sp_tuns(ieee754sp x) 117 { 118 ieee754sp hb = ieee754sp_1e31(); 119 120 /* what if x < 0 ?? */ 121 if (ieee754sp_lt(x, hb)) 122 return (unsigned) ieee754sp_tint(x); 123 124 return (unsigned) ieee754sp_tint(ieee754sp_sub(x, hb)) | 125 ((unsigned) 1 << 31); 126 } 127