1 // SPDX-License-Identifier: GPL-2.0-only 2 /* IEEE754 floating point arithmetic 3 * single precision 4 */ 5 /* 6 * MIPS floating point support 7 * Copyright (C) 1994-2000 Algorithmics Ltd. 8 */ 9 10 #include "ieee754sp.h" 11 12 union ieee754sp ieee754sp_mul(union ieee754sp x, union ieee754sp y) 13 { 14 int re; 15 int rs; 16 unsigned int rm; 17 unsigned short lxm; 18 unsigned short hxm; 19 unsigned short lym; 20 unsigned short hym; 21 unsigned int lrm; 22 unsigned int hrm; 23 unsigned int t; 24 unsigned int at; 25 26 COMPXSP; 27 COMPYSP; 28 29 EXPLODEXSP; 30 EXPLODEYSP; 31 32 ieee754_clearcx(); 33 34 FLUSHXSP; 35 FLUSHYSP; 36 37 switch (CLPAIR(xc, yc)) { 38 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): 39 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): 40 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): 41 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): 42 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): 43 return ieee754sp_nanxcpt(y); 44 45 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): 46 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): 47 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): 48 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): 49 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): 50 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): 51 return ieee754sp_nanxcpt(x); 52 53 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): 54 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): 55 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): 56 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): 57 return y; 58 59 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): 60 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): 61 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): 62 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): 63 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): 64 return x; 65 66 67 /* 68 * Infinity handling 69 */ 70 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): 71 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): 72 ieee754_setcx(IEEE754_INVALID_OPERATION); 73 return ieee754sp_indef(); 74 75 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): 76 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): 77 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): 78 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): 79 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): 80 return ieee754sp_inf(xs ^ ys); 81 82 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): 83 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): 84 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): 85 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): 86 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): 87 return ieee754sp_zero(xs ^ ys); 88 89 90 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): 91 SPDNORMX; 92 fallthrough; 93 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): 94 SPDNORMY; 95 break; 96 97 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): 98 SPDNORMX; 99 break; 100 101 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): 102 break; 103 } 104 /* rm = xm * ym, re = xe+ye basically */ 105 assert(xm & SP_HIDDEN_BIT); 106 assert(ym & SP_HIDDEN_BIT); 107 108 re = xe + ye; 109 rs = xs ^ ys; 110 111 /* shunt to top of word */ 112 xm <<= 32 - (SP_FBITS + 1); 113 ym <<= 32 - (SP_FBITS + 1); 114 115 /* 116 * Multiply 32 bits xm, ym to give high 32 bits rm with stickness. 117 */ 118 lxm = xm & 0xffff; 119 hxm = xm >> 16; 120 lym = ym & 0xffff; 121 hym = ym >> 16; 122 123 lrm = lxm * lym; /* 16 * 16 => 32 */ 124 hrm = hxm * hym; /* 16 * 16 => 32 */ 125 126 t = lxm * hym; /* 16 * 16 => 32 */ 127 at = lrm + (t << 16); 128 hrm += at < lrm; 129 lrm = at; 130 hrm = hrm + (t >> 16); 131 132 t = hxm * lym; /* 16 * 16 => 32 */ 133 at = lrm + (t << 16); 134 hrm += at < lrm; 135 lrm = at; 136 hrm = hrm + (t >> 16); 137 138 rm = hrm | (lrm != 0); 139 140 /* 141 * Sticky shift down to normal rounding precision. 142 */ 143 if ((int) rm < 0) { 144 rm = (rm >> (32 - (SP_FBITS + 1 + 3))) | 145 ((rm << (SP_FBITS + 1 + 3)) != 0); 146 re++; 147 } else { 148 rm = (rm >> (32 - (SP_FBITS + 1 + 3 + 1))) | 149 ((rm << (SP_FBITS + 1 + 3 + 1)) != 0); 150 } 151 assert(rm & (SP_HIDDEN_BIT << 3)); 152 153 return ieee754sp_format(rs, re, rm); 154 } 155