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_QNAN, IEEE754_CLASS_SNAN): 43 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): 44 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): 45 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): 46 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): 47 return ieee754dp_nanxcpt(y); 48 49 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): 50 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): 51 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): 52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): 53 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): 54 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): 55 return ieee754dp_nanxcpt(x); 56 57 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): 58 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): 59 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): 60 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): 61 return y; 62 63 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): 64 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): 65 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): 66 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): 67 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): 68 return x; 69 70 71 /* 72 * Infinity handling 73 */ 74 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): 75 ieee754_setcx(IEEE754_INVALID_OPERATION); 76 return ieee754dp_indef(); 77 78 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): 79 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): 80 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): 81 return ieee754dp_zero(xs ^ ys); 82 83 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): 84 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): 85 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): 86 return ieee754dp_inf(xs ^ ys); 87 88 /* 89 * Zero handling 90 */ 91 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): 92 ieee754_setcx(IEEE754_INVALID_OPERATION); 93 return ieee754dp_indef(); 94 95 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): 96 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): 97 ieee754_setcx(IEEE754_ZERO_DIVIDE); 98 return ieee754dp_inf(xs ^ ys); 99 100 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): 101 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): 102 return ieee754dp_zero(xs == ys ? 0 : 1); 103 104 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): 105 DPDNORMX; 106 /* fall through */ 107 108 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): 109 DPDNORMY; 110 break; 111 112 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): 113 DPDNORMX; 114 break; 115 116 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): 117 break; 118 } 119 assert(xm & DP_HIDDEN_BIT); 120 assert(ym & DP_HIDDEN_BIT); 121 122 /* provide rounding space */ 123 xm <<= 3; 124 ym <<= 3; 125 126 /* now the dirty work */ 127 128 rm = 0; 129 re = xe - ye; 130 131 for (bm = DP_MBIT(DP_FBITS + 2); bm; bm >>= 1) { 132 if (xm >= ym) { 133 xm -= ym; 134 rm |= bm; 135 if (xm == 0) 136 break; 137 } 138 xm <<= 1; 139 } 140 141 rm <<= 1; 142 if (xm) 143 rm |= 1; /* have remainder, set sticky */ 144 145 assert(rm); 146 147 /* 148 * Normalise rm to rounding precision ? 149 */ 150 while ((rm >> (DP_FBITS + 3)) == 0) { 151 rm <<= 1; 152 re--; 153 } 154 155 return ieee754dp_format(xs == ys ? 0 : 1, re, rm); 156 } 157