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 union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y) 25 { 26 u64 rm; 27 int re; 28 u64 bm; 29 30 COMPXDP; 31 COMPYDP; 32 33 EXPLODEXDP; 34 EXPLODEYDP; 35 36 ieee754_clearcx(); 37 38 FLUSHXDP; 39 FLUSHYDP; 40 41 switch (CLPAIR(xc, yc)) { 42 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): 43 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): 44 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): 45 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): 46 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): 47 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): 48 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): 49 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): 50 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): 51 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): 52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): 53 ieee754_setcx(IEEE754_INVALID_OPERATION); 54 return ieee754dp_nanxcpt(ieee754dp_indef()); 55 56 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): 57 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): 58 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): 59 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): 60 return y; 61 62 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): 63 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): 64 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): 65 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): 66 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): 67 return x; 68 69 70 /* 71 * Infinity handling 72 */ 73 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): 74 ieee754_setcx(IEEE754_INVALID_OPERATION); 75 return ieee754dp_indef(); 76 77 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): 78 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): 79 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): 80 return ieee754dp_zero(xs ^ ys); 81 82 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): 83 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): 84 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): 85 return ieee754dp_inf(xs ^ ys); 86 87 /* 88 * Zero handling 89 */ 90 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): 91 ieee754_setcx(IEEE754_INVALID_OPERATION); 92 return ieee754dp_indef(); 93 94 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): 95 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): 96 ieee754_setcx(IEEE754_ZERO_DIVIDE); 97 return ieee754dp_inf(xs ^ ys); 98 99 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): 100 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): 101 return ieee754dp_zero(xs == ys ? 0 : 1); 102 103 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): 104 DPDNORMX; 105 106 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): 107 DPDNORMY; 108 break; 109 110 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): 111 DPDNORMX; 112 break; 113 114 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): 115 break; 116 } 117 assert(xm & DP_HIDDEN_BIT); 118 assert(ym & DP_HIDDEN_BIT); 119 120 /* provide rounding space */ 121 xm <<= 3; 122 ym <<= 3; 123 124 /* now the dirty work */ 125 126 rm = 0; 127 re = xe - ye; 128 129 for (bm = DP_MBIT(DP_FBITS + 2); bm; bm >>= 1) { 130 if (xm >= ym) { 131 xm -= ym; 132 rm |= bm; 133 if (xm == 0) 134 break; 135 } 136 xm <<= 1; 137 } 138 139 rm <<= 1; 140 if (xm) 141 rm |= 1; /* have remainder, set sticky */ 142 143 assert(rm); 144 145 /* 146 * Normalise rm to rounding precision ? 147 */ 148 while ((rm >> (DP_FBITS + 3)) == 0) { 149 rm <<= 1; 150 re--; 151 } 152 153 return ieee754dp_format(xs == ys ? 0 : 1, re, rm); 154 } 155