1 /* IEEE754 floating point arithmetic 2 * single precision 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 "ieee754sp.h" 23 24 union ieee754sp ieee754sp_div(union ieee754sp x, union ieee754sp y) 25 { 26 unsigned rm; 27 int re; 28 unsigned bm; 29 30 COMPXSP; 31 COMPYSP; 32 33 EXPLODEXSP; 34 EXPLODEYSP; 35 36 ieee754_clearcx(); 37 38 FLUSHXSP; 39 FLUSHYSP; 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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_inf(xs ^ ys); 99 100 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): 101 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): 102 return ieee754sp_zero(xs == ys ? 0 : 1); 103 104 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): 105 SPDNORMX; 106 107 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): 108 SPDNORMY; 109 break; 110 111 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): 112 SPDNORMX; 113 break; 114 115 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): 116 break; 117 } 118 assert(xm & SP_HIDDEN_BIT); 119 assert(ym & SP_HIDDEN_BIT); 120 121 /* provide rounding space */ 122 xm <<= 3; 123 ym <<= 3; 124 125 /* now the dirty work */ 126 127 rm = 0; 128 re = xe - ye; 129 130 for (bm = SP_MBIT(SP_FBITS + 2); bm; bm >>= 1) { 131 if (xm >= ym) { 132 xm -= ym; 133 rm |= bm; 134 if (xm == 0) 135 break; 136 } 137 xm <<= 1; 138 } 139 140 rm <<= 1; 141 if (xm) 142 rm |= 1; /* have remainder, set sticky */ 143 144 assert(rm); 145 146 /* normalise rm to rounding precision ? 147 */ 148 while ((rm >> (SP_FBITS + 3)) == 0) { 149 rm <<= 1; 150 re--; 151 } 152 153 return ieee754sp_format(xs == ys ? 0 : 1, re, rm); 154 } 155