1 /* IEEE754 floating point arithmetic 2 * single precision 3 */ 4 /* 5 * MIPS floating point support 6 * Copyright (C) 1994-2000 Algorithmics Ltd. 7 * 8 * ######################################################################## 9 * 10 * This program is free software; you can distribute it and/or modify it 11 * under the terms of the GNU General Public License (Version 2) as 12 * published by the Free Software Foundation. 13 * 14 * This program is distributed in the hope it will be useful, but WITHOUT 15 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 16 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 17 * for more details. 18 * 19 * You should have received a copy of the GNU General Public License along 20 * with this program; if not, write to the Free Software Foundation, Inc., 21 * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. 22 * 23 * ######################################################################## 24 */ 25 26 27 #include "ieee754sp.h" 28 29 ieee754sp ieee754sp_mul(ieee754sp x, ieee754sp y) 30 { 31 COMPXSP; 32 COMPYSP; 33 34 EXPLODEXSP; 35 EXPLODEYSP; 36 37 CLEARCX; 38 39 FLUSHXSP; 40 FLUSHYSP; 41 42 switch (CLPAIR(xc, yc)) { 43 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): 44 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): 45 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): 46 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): 47 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): 48 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): 49 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): 50 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): 51 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): 52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): 53 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): 54 SETCX(IEEE754_INVALID_OPERATION); 55 return ieee754sp_nanxcpt(ieee754sp_indef(), "mul", x, y); 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 /* Infinity handling */ 72 73 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): 74 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): 75 SETCX(IEEE754_INVALID_OPERATION); 76 return ieee754sp_xcpt(ieee754sp_indef(), "mul", x, y); 77 78 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): 79 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): 80 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): 81 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): 82 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): 83 return ieee754sp_inf(xs ^ ys); 84 85 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): 86 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): 87 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): 88 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): 89 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): 90 return ieee754sp_zero(xs ^ ys); 91 92 93 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): 94 SPDNORMX; 95 96 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): 97 SPDNORMY; 98 break; 99 100 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): 101 SPDNORMX; 102 break; 103 104 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): 105 break; 106 } 107 /* rm = xm * ym, re = xe+ye basically */ 108 assert(xm & SP_HIDDEN_BIT); 109 assert(ym & SP_HIDDEN_BIT); 110 111 { 112 int re = xe + ye; 113 int rs = xs ^ ys; 114 unsigned rm; 115 116 /* shunt to top of word */ 117 xm <<= 32 - (SP_MBITS + 1); 118 ym <<= 32 - (SP_MBITS + 1); 119 120 /* multiply 32bits xm,ym to give high 32bits rm with stickness 121 */ 122 { 123 unsigned short lxm = xm & 0xffff; 124 unsigned short hxm = xm >> 16; 125 unsigned short lym = ym & 0xffff; 126 unsigned short hym = ym >> 16; 127 unsigned lrm; 128 unsigned hrm; 129 130 lrm = lxm * lym; /* 16 * 16 => 32 */ 131 hrm = hxm * hym; /* 16 * 16 => 32 */ 132 133 { 134 unsigned t = lxm * hym; /* 16 * 16 => 32 */ 135 { 136 unsigned at = lrm + (t << 16); 137 hrm += at < lrm; 138 lrm = at; 139 } 140 hrm = hrm + (t >> 16); 141 } 142 143 { 144 unsigned t = hxm * lym; /* 16 * 16 => 32 */ 145 { 146 unsigned at = lrm + (t << 16); 147 hrm += at < lrm; 148 lrm = at; 149 } 150 hrm = hrm + (t >> 16); 151 } 152 rm = hrm | (lrm != 0); 153 } 154 155 /* 156 * sticky shift down to normal rounding precision 157 */ 158 if ((int) rm < 0) { 159 rm = (rm >> (32 - (SP_MBITS + 1 + 3))) | 160 ((rm << (SP_MBITS + 1 + 3)) != 0); 161 re++; 162 } else { 163 rm = (rm >> (32 - (SP_MBITS + 1 + 3 + 1))) | 164 ((rm << (SP_MBITS + 1 + 3 + 1)) != 0); 165 } 166 assert(rm & (SP_HIDDEN_BIT << 3)); 167 168 SPNORMRET2(rs, re, rm, "mul", x, y); 169 } 170 } 171