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_mul(union ieee754sp x, union ieee754sp y) 25 { 26 int re; 27 int rs; 28 unsigned int rm; 29 unsigned short lxm; 30 unsigned short hxm; 31 unsigned short lym; 32 unsigned short hym; 33 unsigned int lrm; 34 unsigned int hrm; 35 unsigned int t; 36 unsigned int at; 37 38 COMPXSP; 39 COMPYSP; 40 41 EXPLODEXSP; 42 EXPLODEYSP; 43 44 ieee754_clearcx(); 45 46 FLUSHXSP; 47 FLUSHYSP; 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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_zero(xs ^ ys); 100 101 102 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): 103 SPDNORMX; 104 /* fall through */ 105 106 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): 107 SPDNORMY; 108 break; 109 110 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): 111 SPDNORMX; 112 break; 113 114 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): 115 break; 116 } 117 /* rm = xm * ym, re = xe+ye basically */ 118 assert(xm & SP_HIDDEN_BIT); 119 assert(ym & SP_HIDDEN_BIT); 120 121 re = xe + ye; 122 rs = xs ^ ys; 123 124 /* shunt to top of word */ 125 xm <<= 32 - (SP_FBITS + 1); 126 ym <<= 32 - (SP_FBITS + 1); 127 128 /* 129 * Multiply 32 bits xm, ym to give high 32 bits rm with stickness. 130 */ 131 lxm = xm & 0xffff; 132 hxm = xm >> 16; 133 lym = ym & 0xffff; 134 hym = ym >> 16; 135 136 lrm = lxm * lym; /* 16 * 16 => 32 */ 137 hrm = hxm * hym; /* 16 * 16 => 32 */ 138 139 t = lxm * hym; /* 16 * 16 => 32 */ 140 at = lrm + (t << 16); 141 hrm += at < lrm; 142 lrm = at; 143 hrm = hrm + (t >> 16); 144 145 t = hxm * lym; /* 16 * 16 => 32 */ 146 at = lrm + (t << 16); 147 hrm += at < lrm; 148 lrm = at; 149 hrm = hrm + (t >> 16); 150 151 rm = hrm | (lrm != 0); 152 153 /* 154 * Sticky shift down to normal rounding precision. 155 */ 156 if ((int) rm < 0) { 157 rm = (rm >> (32 - (SP_FBITS + 1 + 3))) | 158 ((rm << (SP_FBITS + 1 + 3)) != 0); 159 re++; 160 } else { 161 rm = (rm >> (32 - (SP_FBITS + 1 + 3 + 1))) | 162 ((rm << (SP_FBITS + 1 + 3 + 1)) != 0); 163 } 164 assert(rm & (SP_HIDDEN_BIT << 3)); 165 166 return ieee754sp_format(rs, re, rm); 167 } 168