1 2 /*============================================================================ 3 4 This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic 5 Package, Release 3e, by John R. Hauser. 6 7 Copyright 2011, 2012, 2013, 2014, 2015, 2016 The Regents of the University of 8 California. All rights reserved. 9 10 Redistribution and use in source and binary forms, with or without 11 modification, are permitted provided that the following conditions are met: 12 13 1. Redistributions of source code must retain the above copyright notice, 14 this list of conditions, and the following disclaimer. 15 16 2. Redistributions in binary form must reproduce the above copyright notice, 17 this list of conditions, and the following disclaimer in the documentation 18 and/or other materials provided with the distribution. 19 20 3. Neither the name of the University nor the names of its contributors may 21 be used to endorse or promote products derived from this software without 22 specific prior written permission. 23 24 THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY 25 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 26 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE 27 DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY 28 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 29 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 30 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 31 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 33 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 35 =============================================================================*/ 36 37 #include <stdbool.h> 38 #include <stdint.h> 39 #include "platform.h" 40 #include "internals.h" 41 #include "specialize.h" 42 #include "softfloat.h" 43 44 float16_t softfloat_mulAddF16(uint_fast16_t uiA,uint_fast16_t uiB,uint_fast16_t uiC,uint_fast8_t op)45 softfloat_mulAddF16( 46 uint_fast16_t uiA, uint_fast16_t uiB, uint_fast16_t uiC, uint_fast8_t op ) 47 { 48 bool signA; 49 int_fast8_t expA; 50 uint_fast16_t sigA; 51 bool signB; 52 int_fast8_t expB; 53 uint_fast16_t sigB; 54 bool signC; 55 int_fast8_t expC; 56 uint_fast16_t sigC; 57 bool signProd; 58 uint_fast16_t magBits, uiZ; 59 struct exp8_sig16 normExpSig; 60 int_fast8_t expProd; 61 uint_fast32_t sigProd; 62 bool signZ; 63 int_fast8_t expZ; 64 uint_fast16_t sigZ; 65 int_fast8_t expDiff; 66 uint_fast32_t sig32Z, sig32C; 67 int_fast8_t shiftDist; 68 union ui16_f16 uZ; 69 70 /*------------------------------------------------------------------------ 71 *------------------------------------------------------------------------*/ 72 signA = signF16UI( uiA ); 73 expA = expF16UI( uiA ); 74 sigA = fracF16UI( uiA ); 75 signB = signF16UI( uiB ); 76 expB = expF16UI( uiB ); 77 sigB = fracF16UI( uiB ); 78 signC = signF16UI( uiC ) ^ (op == softfloat_mulAdd_subC); 79 expC = expF16UI( uiC ); 80 sigC = fracF16UI( uiC ); 81 signProd = signA ^ signB ^ (op == softfloat_mulAdd_subProd); 82 /*------------------------------------------------------------------------ 83 *------------------------------------------------------------------------*/ 84 if ( expA == 0x1F ) { 85 if ( sigA || ((expB == 0x1F) && sigB) ) goto propagateNaN_ABC; 86 magBits = expB | sigB; 87 goto infProdArg; 88 } 89 if ( expB == 0x1F ) { 90 if ( sigB ) goto propagateNaN_ABC; 91 magBits = expA | sigA; 92 goto infProdArg; 93 } 94 if ( expC == 0x1F ) { 95 if ( sigC ) { 96 uiZ = 0; 97 goto propagateNaN_ZC; 98 } 99 uiZ = uiC; 100 goto uiZ; 101 } 102 /*------------------------------------------------------------------------ 103 *------------------------------------------------------------------------*/ 104 if ( ! expA ) { 105 if ( ! sigA ) goto zeroProd; 106 normExpSig = softfloat_normSubnormalF16Sig( sigA ); 107 expA = normExpSig.exp; 108 sigA = normExpSig.sig; 109 } 110 if ( ! expB ) { 111 if ( ! sigB ) goto zeroProd; 112 normExpSig = softfloat_normSubnormalF16Sig( sigB ); 113 expB = normExpSig.exp; 114 sigB = normExpSig.sig; 115 } 116 /*------------------------------------------------------------------------ 117 *------------------------------------------------------------------------*/ 118 expProd = expA + expB - 0xE; 119 sigA = (sigA | 0x0400)<<4; 120 sigB = (sigB | 0x0400)<<4; 121 sigProd = (uint_fast32_t) sigA * sigB; 122 if ( sigProd < 0x20000000 ) { 123 --expProd; 124 sigProd <<= 1; 125 } 126 signZ = signProd; 127 if ( ! expC ) { 128 if ( ! sigC ) { 129 expZ = expProd - 1; 130 sigZ = sigProd>>15 | ((sigProd & 0x7FFF) != 0); 131 goto roundPack; 132 } 133 normExpSig = softfloat_normSubnormalF16Sig( sigC ); 134 expC = normExpSig.exp; 135 sigC = normExpSig.sig; 136 } 137 sigC = (sigC | 0x0400)<<3; 138 /*------------------------------------------------------------------------ 139 *------------------------------------------------------------------------*/ 140 expDiff = expProd - expC; 141 if ( signProd == signC ) { 142 /*-------------------------------------------------------------------- 143 *--------------------------------------------------------------------*/ 144 if ( expDiff <= 0 ) { 145 expZ = expC; 146 sigZ = sigC + softfloat_shiftRightJam32( sigProd, 16 - expDiff ); 147 } else { 148 expZ = expProd; 149 sig32Z = 150 sigProd 151 + softfloat_shiftRightJam32( 152 (uint_fast32_t) sigC<<16, expDiff ); 153 sigZ = sig32Z>>16 | ((sig32Z & 0xFFFF) != 0 ); 154 } 155 if ( sigZ < 0x4000 ) { 156 --expZ; 157 sigZ <<= 1; 158 } 159 } else { 160 /*-------------------------------------------------------------------- 161 *--------------------------------------------------------------------*/ 162 sig32C = (uint_fast32_t) sigC<<16; 163 if ( expDiff < 0 ) { 164 signZ = signC; 165 expZ = expC; 166 sig32Z = sig32C - softfloat_shiftRightJam32( sigProd, -expDiff ); 167 } else if ( ! expDiff ) { 168 expZ = expProd; 169 sig32Z = sigProd - sig32C; 170 if ( ! sig32Z ) goto completeCancellation; 171 if ( sig32Z & 0x80000000 ) { 172 signZ = ! signZ; 173 sig32Z = -sig32Z; 174 } 175 } else { 176 expZ = expProd; 177 sig32Z = sigProd - softfloat_shiftRightJam32( sig32C, expDiff ); 178 } 179 shiftDist = softfloat_countLeadingZeros32( sig32Z ) - 1; 180 expZ -= shiftDist; 181 shiftDist -= 16; 182 if ( shiftDist < 0 ) { 183 sigZ = 184 sig32Z>>(-shiftDist) 185 | ((uint32_t) (sig32Z<<(shiftDist & 31)) != 0); 186 } else { 187 sigZ = (uint_fast16_t) sig32Z<<shiftDist; 188 } 189 } 190 roundPack: 191 return softfloat_roundPackToF16( signZ, expZ, sigZ ); 192 /*------------------------------------------------------------------------ 193 *------------------------------------------------------------------------*/ 194 propagateNaN_ABC: 195 uiZ = softfloat_propagateNaNF16UI( uiA, uiB ); 196 goto propagateNaN_ZC; 197 /*------------------------------------------------------------------------ 198 *------------------------------------------------------------------------*/ 199 infProdArg: 200 if ( magBits ) { 201 uiZ = packToF16UI( signProd, 0x1F, 0 ); 202 if ( expC != 0x1F ) goto uiZ; 203 if ( sigC ) goto propagateNaN_ZC; 204 if ( signProd == signC ) goto uiZ; 205 } 206 softfloat_raiseFlags( softfloat_flag_invalid ); 207 uiZ = defaultNaNF16UI; 208 propagateNaN_ZC: 209 uiZ = softfloat_propagateNaNF16UI( uiZ, uiC ); 210 goto uiZ; 211 /*------------------------------------------------------------------------ 212 *------------------------------------------------------------------------*/ 213 zeroProd: 214 uiZ = uiC; 215 if ( ! (expC | sigC) && (signProd != signC) ) { 216 completeCancellation: 217 uiZ = 218 packToF16UI( 219 (softfloat_roundingMode == softfloat_round_min), 0, 0 ); 220 } 221 uiZ: 222 uZ.ui = uiZ; 223 return uZ.f; 224 225 } 226 227