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 * 8 * This program is free software; you can distribute it and/or modify it 9 * under the terms of the GNU General Public License (Version 2) as 10 * published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * for more details. 16 * 17 * You should have received a copy of the GNU General Public License along 18 * with this program; if not, write to the Free Software Foundation, Inc., 19 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 */ 21 22 #include "ieee754dp.h" 23 24 s64 ieee754dp_tlong(union ieee754dp x) 25 { 26 u64 residue; 27 int round; 28 int sticky; 29 int odd; 30 31 COMPXDP; 32 33 ieee754_clearcx(); 34 35 EXPLODEXDP; 36 FLUSHXDP; 37 38 switch (xc) { 39 case IEEE754_CLASS_SNAN: 40 case IEEE754_CLASS_QNAN: 41 case IEEE754_CLASS_INF: 42 ieee754_setcx(IEEE754_INVALID_OPERATION); 43 return ieee754di_indef(); 44 45 case IEEE754_CLASS_ZERO: 46 return 0; 47 48 case IEEE754_CLASS_DNORM: 49 case IEEE754_CLASS_NORM: 50 break; 51 } 52 if (xe >= 63) { 53 /* look for valid corner case */ 54 if (xe == 63 && xs && xm == DP_HIDDEN_BIT) 55 return -0x8000000000000000LL; 56 /* Set invalid. We will only use overflow for floating 57 point overflow */ 58 ieee754_setcx(IEEE754_INVALID_OPERATION); 59 return ieee754di_indef(); 60 } 61 /* oh gawd */ 62 if (xe > DP_FBITS) { 63 xm <<= xe - DP_FBITS; 64 } else if (xe < DP_FBITS) { 65 if (xe < -1) { 66 residue = xm; 67 round = 0; 68 sticky = residue != 0; 69 xm = 0; 70 } else { 71 /* Shifting a u64 64 times does not work, 72 * so we do it in two steps. Be aware that xe 73 * may be -1 */ 74 residue = xm << (xe + 1); 75 residue <<= 63 - DP_FBITS; 76 round = (residue >> 63) != 0; 77 sticky = (residue << 1) != 0; 78 xm >>= DP_FBITS - xe; 79 } 80 odd = (xm & 0x1) != 0x0; 81 switch (ieee754_csr.rm) { 82 case FPU_CSR_RN: 83 if (round && (sticky || odd)) 84 xm++; 85 break; 86 case FPU_CSR_RZ: 87 break; 88 case FPU_CSR_RU: /* toward +Infinity */ 89 if ((round || sticky) && !xs) 90 xm++; 91 break; 92 case FPU_CSR_RD: /* toward -Infinity */ 93 if ((round || sticky) && xs) 94 xm++; 95 break; 96 } 97 if ((xm >> 63) != 0) { 98 /* This can happen after rounding */ 99 ieee754_setcx(IEEE754_INVALID_OPERATION); 100 return ieee754di_indef(); 101 } 102 if (round || sticky) 103 ieee754_setcx(IEEE754_INEXACT); 104 } 105 if (xs) 106 return -xm; 107 else 108 return xm; 109 } 110