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 int ieee754dp_tint(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 ieee754si_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 > 31) { 53 /* Set invalid. We will only use overflow for floating 54 point overflow */ 55 ieee754_setcx(IEEE754_INVALID_OPERATION); 56 return ieee754si_indef(); 57 } 58 /* oh gawd */ 59 if (xe > DP_FBITS) { 60 xm <<= xe - DP_FBITS; 61 } else if (xe < DP_FBITS) { 62 if (xe < -1) { 63 residue = xm; 64 round = 0; 65 sticky = residue != 0; 66 xm = 0; 67 } else { 68 residue = xm << (64 - DP_FBITS + xe); 69 round = (residue >> 63) != 0; 70 sticky = (residue << 1) != 0; 71 xm >>= DP_FBITS - xe; 72 } 73 /* Note: At this point upper 32 bits of xm are guaranteed 74 to be zero */ 75 odd = (xm & 0x1) != 0x0; 76 switch (ieee754_csr.rm) { 77 case FPU_CSR_RN: 78 if (round && (sticky || odd)) 79 xm++; 80 break; 81 case FPU_CSR_RZ: 82 break; 83 case FPU_CSR_RU: /* toward +Infinity */ 84 if ((round || sticky) && !xs) 85 xm++; 86 break; 87 case FPU_CSR_RD: /* toward -Infinity */ 88 if ((round || sticky) && xs) 89 xm++; 90 break; 91 } 92 /* look for valid corner case 0x80000000 */ 93 if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) { 94 /* This can happen after rounding */ 95 ieee754_setcx(IEEE754_INVALID_OPERATION); 96 return ieee754si_indef(); 97 } 98 if (round || sticky) 99 ieee754_setcx(IEEE754_INEXACT); 100 } 101 if (xs) 102 return -xm; 103 else 104 return xm; 105 } 106