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 30 ieee754sp ieee754sp_add(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(), "add", 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 75 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): 76 if (xs == ys) 77 return x; 78 SETCX(IEEE754_INVALID_OPERATION); 79 return ieee754sp_xcpt(ieee754sp_indef(), "add", x, y); 80 81 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): 82 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): 83 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): 84 return y; 85 86 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): 87 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): 88 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): 89 return x; 90 91 /* Zero handling 92 */ 93 94 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): 95 if (xs == ys) 96 return x; 97 else 98 return ieee754sp_zero(ieee754_csr.rm == 99 IEEE754_RD); 100 101 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): 102 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): 103 return x; 104 105 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): 106 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): 107 return y; 108 109 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): 110 SPDNORMX; 111 112 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): 113 SPDNORMY; 114 break; 115 116 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): 117 SPDNORMX; 118 break; 119 120 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): 121 break; 122 } 123 assert(xm & SP_HIDDEN_BIT); 124 assert(ym & SP_HIDDEN_BIT); 125 126 /* provide guard,round and stick bit space */ 127 xm <<= 3; 128 ym <<= 3; 129 130 if (xe > ye) { 131 /* have to shift y fraction right to align 132 */ 133 int s = xe - ye; 134 SPXSRSYn(s); 135 } else if (ye > xe) { 136 /* have to shift x fraction right to align 137 */ 138 int s = ye - xe; 139 SPXSRSXn(s); 140 } 141 assert(xe == ye); 142 assert(xe <= SP_EMAX); 143 144 if (xs == ys) { 145 /* generate 28 bit result of adding two 27 bit numbers 146 * leaving result in xm,xs,xe 147 */ 148 xm = xm + ym; 149 xe = xe; 150 xs = xs; 151 152 if (xm >> (SP_MBITS + 1 + 3)) { /* carry out */ 153 SPXSRSX1(); 154 } 155 } else { 156 if (xm >= ym) { 157 xm = xm - ym; 158 xe = xe; 159 xs = xs; 160 } else { 161 xm = ym - xm; 162 xe = xe; 163 xs = ys; 164 } 165 if (xm == 0) 166 return ieee754sp_zero(ieee754_csr.rm == 167 IEEE754_RD); 168 169 /* normalize in extended single precision */ 170 while ((xm >> (SP_MBITS + 3)) == 0) { 171 xm <<= 1; 172 xe--; 173 } 174 175 } 176 SPNORMRET2(xs, xe, xm, "add", x, y); 177 } 178