1/* IEEE754 floating point arithmetic 2 * single precision 3 */ 4/* 5 * MIPS floating point support 6 * Copyright (C) 1994-2000 Algorithmics Ltd. 7 * http://www.algor.co.uk 8 * 9 * ######################################################################## 10 * 11 * This program is free software; you can distribute it and/or modify it 12 * under the terms of the GNU General Public License (Version 2) as 13 * published by the Free Software Foundation. 14 * 15 * This program is distributed in the hope it will be useful, but WITHOUT 16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 17 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 18 * for more details. 19 * 20 * You should have received a copy of the GNU General Public License along 21 * with this program; if not, write to the Free Software Foundation, Inc., 22 * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. 23 * 24 * ######################################################################## 25 */ 26 27 28#include "ieee754sp.h" 29 30ieee754sp ieee754sp_mul(ieee754sp x, ieee754sp y) 31{ 32 COMPXSP; 33 COMPYSP; 34 35 EXPLODEXSP; 36 EXPLODEYSP; 37 38 CLEARCX; 39 40 FLUSHXSP; 41 FLUSHYSP; 42 43 switch (CLPAIR(xc, yc)) { 44 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): 45 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): 46 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): 47 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): 48 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): 49 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): 50 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): 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 SETCX(IEEE754_INVALID_OPERATION); 56 return ieee754sp_nanxcpt(ieee754sp_indef(), "mul", x, y); 57 58 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): 59 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): 60 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): 61 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): 62 return y; 63 64 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): 65 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): 66 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): 67 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): 68 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): 69 return x; 70 71 72 /* Infinity handling */ 73 74 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): 75 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): 76 SETCX(IEEE754_INVALID_OPERATION); 77 return ieee754sp_xcpt(ieee754sp_indef(), "mul", x, y); 78 79 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): 80 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): 81 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): 82 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): 83 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): 84 return ieee754sp_inf(xs ^ ys); 85 86 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): 87 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): 88 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): 89 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): 90 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): 91 return ieee754sp_zero(xs ^ ys); 92 93 94 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): 95 SPDNORMX; 96 97 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): 98 SPDNORMY; 99 break; 100 101 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): 102 SPDNORMX; 103 break; 104 105 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): 106 break; 107 } 108 /* rm = xm * ym, re = xe+ye basicly */ 109 assert(xm & SP_HIDDEN_BIT); 110 assert(ym & SP_HIDDEN_BIT); 111 112 { 113 int re = xe + ye; 114 int rs = xs ^ ys; 115 unsigned rm; 116 117 /* shunt to top of word */ 118 xm <<= 32 - (SP_MBITS + 1); 119 ym <<= 32 - (SP_MBITS + 1); 120 121 /* multiply 32bits xm,ym to give high 32bits rm with stickness 122 */ 123 { 124 unsigned short lxm = xm & 0xffff; 125 unsigned short hxm = xm >> 16; 126 unsigned short lym = ym & 0xffff; 127 unsigned short hym = ym >> 16; 128 unsigned lrm; 129 unsigned hrm; 130 131 lrm = lxm * lym; /* 16 * 16 => 32 */ 132 hrm = hxm * hym; /* 16 * 16 => 32 */ 133 134 { 135 unsigned t = lxm * hym; /* 16 * 16 => 32 */ 136 { 137 unsigned at = lrm + (t << 16); 138 hrm += at < lrm; 139 lrm = at; 140 } 141 hrm = hrm + (t >> 16); 142 } 143 144 { 145 unsigned t = hxm * lym; /* 16 * 16 => 32 */ 146 { 147 unsigned at = lrm + (t << 16); 148 hrm += at < lrm; 149 lrm = at; 150 } 151 hrm = hrm + (t >> 16); 152 } 153 rm = hrm | (lrm != 0); 154 } 155 156 /* 157 * sticky shift down to normal rounding precision 158 */ 159 if ((int) rm < 0) { 160 rm = (rm >> (32 - (SP_MBITS + 1 + 3))) | 161 ((rm << (SP_MBITS + 1 + 3)) != 0); 162 re++; 163 } else { 164 rm = (rm >> (32 - (SP_MBITS + 1 + 3 + 1))) | 165 ((rm << (SP_MBITS + 1 + 3 + 1)) != 0); 166 } 167 assert(rm & (SP_HIDDEN_BIT << 3)); 168 169 SPNORMRET2(rs, re, rm, "mul", x, y); 170 } 171} 172