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_mul(union ieee754dp x, union ieee754dp y) 25 { 26 int re; 27 int rs; 28 u64 rm; 29 unsigned int lxm; 30 unsigned int hxm; 31 unsigned int lym; 32 unsigned int hym; 33 u64 lrm; 34 u64 hrm; 35 u64 t; 36 u64 at; 37 38 COMPXDP; 39 COMPYDP; 40 41 EXPLODEXDP; 42 EXPLODEYDP; 43 44 ieee754_clearcx(); 45 46 FLUSHXDP; 47 FLUSHYDP; 48 49 switch (CLPAIR(xc, yc)) { 50 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): 51 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): 52 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): 53 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): 54 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): 55 return ieee754dp_nanxcpt(y); 56 57 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): 58 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): 59 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): 60 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): 61 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): 62 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): 63 return ieee754dp_nanxcpt(x); 64 65 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): 66 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): 67 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): 68 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): 69 return y; 70 71 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): 72 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): 73 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): 74 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): 75 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): 76 return x; 77 78 79 /* 80 * Infinity handling 81 */ 82 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): 83 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): 84 ieee754_setcx(IEEE754_INVALID_OPERATION); 85 return ieee754dp_indef(); 86 87 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): 88 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): 89 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): 90 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): 91 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): 92 return ieee754dp_inf(xs ^ ys); 93 94 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): 95 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): 96 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): 97 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): 98 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): 99 return ieee754dp_zero(xs ^ ys); 100 101 102 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): 103 DPDNORMX; 104 105 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): 106 DPDNORMY; 107 break; 108 109 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): 110 DPDNORMX; 111 break; 112 113 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): 114 break; 115 } 116 /* rm = xm * ym, re = xe+ye basically */ 117 assert(xm & DP_HIDDEN_BIT); 118 assert(ym & DP_HIDDEN_BIT); 119 120 re = xe + ye; 121 rs = xs ^ ys; 122 123 /* shunt to top of word */ 124 xm <<= 64 - (DP_FBITS + 1); 125 ym <<= 64 - (DP_FBITS + 1); 126 127 /* 128 * Multiply 64 bits xm, ym to give high 64 bits rm with stickness. 129 */ 130 131 lxm = xm; 132 hxm = xm >> 32; 133 lym = ym; 134 hym = ym >> 32; 135 136 lrm = DPXMULT(lxm, lym); 137 hrm = DPXMULT(hxm, hym); 138 139 t = DPXMULT(lxm, hym); 140 141 at = lrm + (t << 32); 142 hrm += at < lrm; 143 lrm = at; 144 145 hrm = hrm + (t >> 32); 146 147 t = DPXMULT(hxm, lym); 148 149 at = lrm + (t << 32); 150 hrm += at < lrm; 151 lrm = at; 152 153 hrm = hrm + (t >> 32); 154 155 rm = hrm | (lrm != 0); 156 157 /* 158 * Sticky shift down to normal rounding precision. 159 */ 160 if ((s64) rm < 0) { 161 rm = (rm >> (64 - (DP_FBITS + 1 + 3))) | 162 ((rm << (DP_FBITS + 1 + 3)) != 0); 163 re++; 164 } else { 165 rm = (rm >> (64 - (DP_FBITS + 1 + 3 + 1))) | 166 ((rm << (DP_FBITS + 1 + 3 + 1)) != 0); 167 } 168 assert(rm & (DP_HIDDEN_BIT << 3)); 169 170 return ieee754dp_format(rs, re, rm); 171 } 172