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 } 75 else { 76 /* Shifting a u64 64 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 <<= 63 - DP_MBITS; 81 round = (residue >> 63) != 0; 82 sticky = (residue << 1) != 0; 83 xm >>= DP_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 >> 63) != 0) { 103 /* This can happen after rounding */ 104 SETCX(IEEE754_INVALID_OPERATION); 105 return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", 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 u64 ieee754dp_tulong(ieee754dp x) 118 { 119 ieee754dp hb = ieee754dp_1e63(); 120 121 /* what if x < 0 ?? */ 122 if (ieee754dp_lt(x, hb)) 123 return (u64) ieee754dp_tlong(x); 124 125 return (u64) ieee754dp_tlong(ieee754dp_sub(x, hb)) | 126 (1ULL << 63); 127 } 128