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 ieee754_setcx(IEEE754_INVALID_OPERATION); 42 return ieee754di_indef(); 43 44 case IEEE754_CLASS_INF: 45 ieee754_setcx(IEEE754_INVALID_OPERATION); 46 return ieee754di_overflow(xs); 47 48 case IEEE754_CLASS_ZERO: 49 return 0; 50 51 case IEEE754_CLASS_DNORM: 52 case IEEE754_CLASS_NORM: 53 break; 54 } 55 if (xe >= 63) { 56 /* look for valid corner case */ 57 if (xe == 63 && xs && xm == DP_HIDDEN_BIT) 58 return -0x8000000000000000LL; 59 /* Set invalid. We will only use overflow for floating 60 point overflow */ 61 ieee754_setcx(IEEE754_INVALID_OPERATION); 62 return ieee754di_overflow(xs); 63 } 64 /* oh gawd */ 65 if (xe > DP_FBITS) { 66 xm <<= xe - DP_FBITS; 67 } else if (xe < DP_FBITS) { 68 if (xe < -1) { 69 residue = xm; 70 round = 0; 71 sticky = residue != 0; 72 xm = 0; 73 } else { 74 /* Shifting a u64 64 times does not work, 75 * so we do it in two steps. Be aware that xe 76 * may be -1 */ 77 residue = xm << (xe + 1); 78 residue <<= 63 - DP_FBITS; 79 round = (residue >> 63) != 0; 80 sticky = (residue << 1) != 0; 81 xm >>= DP_FBITS - xe; 82 } 83 odd = (xm & 0x1) != 0x0; 84 switch (ieee754_csr.rm) { 85 case FPU_CSR_RN: 86 if (round && (sticky || odd)) 87 xm++; 88 break; 89 case FPU_CSR_RZ: 90 break; 91 case FPU_CSR_RU: /* toward +Infinity */ 92 if ((round || sticky) && !xs) 93 xm++; 94 break; 95 case FPU_CSR_RD: /* toward -Infinity */ 96 if ((round || sticky) && xs) 97 xm++; 98 break; 99 } 100 if ((xm >> 63) != 0) { 101 /* This can happen after rounding */ 102 ieee754_setcx(IEEE754_INVALID_OPERATION); 103 return ieee754di_overflow(xs); 104 } 105 if (round || sticky) 106 ieee754_setcx(IEEE754_INEXACT); 107 } 108 if (xs) 109 return -xm; 110 else 111 return xm; 112 } 113