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 "ieee754dp.h" 29 30 s64 ieee754dp_tlong(ieee754dp x) 31 { 32 COMPXDP; 33 34 CLEARCX; 35 36 EXPLODEXDP; 37 FLUSHXDP; 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 ieee754di_xcpt(ieee754di_indef(), "dp_tlong", 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 >= 63) { 52 /* look for valid corner case */ 53 if (xe == 63 && xs && xm == DP_HIDDEN_BIT) 54 return -0x8000000000000000LL; 55 /* Set invalid. We will only use overflow for floating 56 point overflow */ 57 SETCX(IEEE754_INVALID_OPERATION); 58 return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x); 59 } 60 /* oh gawd */ 61 if (xe > DP_MBITS) { 62 xm <<= xe - DP_MBITS; 63 } else if (xe < DP_MBITS) { 64 u64 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 u64 64 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 <<= 63 - DP_MBITS; 80 round = (residue >> 63) != 0; 81 sticky = (residue << 1) != 0; 82 xm >>= DP_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 >> 63) != 0) { 102 /* This can happen after rounding */ 103 SETCX(IEEE754_INVALID_OPERATION); 104 return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", 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 u64 ieee754dp_tulong(ieee754dp x) 117 { 118 ieee754dp hb = ieee754dp_1e63(); 119 120 /* what if x < 0 ?? */ 121 if (ieee754dp_lt(x, hb)) 122 return (u64) ieee754dp_tlong(x); 123 124 return (u64) ieee754dp_tlong(ieee754dp_sub(x, hb)) | 125 (1ULL << 63); 126 } 127