1 // SPDX-License-Identifier: BSD-3-Clause 2 3 /*============================================================================ 4 5 This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic 6 Package, Release 3a, by John R. Hauser. 7 8 Copyright 2011, 2012, 2013, 2014, 2015 The Regents of the University of 9 California. All rights reserved. 10 11 Redistribution and use in source and binary forms, with or without 12 modification, are permitted provided that the following conditions are met: 13 14 1. Redistributions of source code must retain the above copyright notice, 15 this list of conditions, and the following disclaimer. 16 17 2. Redistributions in binary form must reproduce the above copyright notice, 18 this list of conditions, and the following disclaimer in the documentation 19 and/or other materials provided with the distribution. 20 21 3. Neither the name of the University nor the names of its contributors may 22 be used to endorse or promote products derived from this software without 23 specific prior written permission. 24 25 THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY 26 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 27 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE 28 DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY 29 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 30 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 31 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 32 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 34 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 36 =============================================================================*/ 37 38 #include <stdbool.h> 39 #include <stdint.h> 40 #include "platform.h" 41 #include "internals.h" 42 #include "softfloat.h" 43 44 void softfloat_roundPackMToExtF80M(bool sign,int32_t exp,uint32_t * extSigPtr,uint_fast8_t roundingPrecision,struct extFloat80M * zSPtr)45 softfloat_roundPackMToExtF80M( 46 bool sign, 47 int32_t exp, 48 uint32_t *extSigPtr, 49 uint_fast8_t roundingPrecision, 50 struct extFloat80M *zSPtr 51 ) 52 { 53 uint_fast8_t roundingMode; 54 bool roundNearEven; 55 uint64_t sig, roundIncrement, roundMask, roundBits; 56 bool isTiny; 57 uint32_t sigExtra; 58 bool doIncrement; 59 60 /*------------------------------------------------------------------------ 61 *------------------------------------------------------------------------*/ 62 roundingMode = softfloat_roundingMode; 63 roundNearEven = (roundingMode == softfloat_round_near_even); 64 sig = 65 (uint64_t) extSigPtr[indexWord( 3, 2 )]<<32 66 | extSigPtr[indexWord( 3, 1 )]; 67 if ( roundingPrecision == 80 ) goto precision80; 68 if ( roundingPrecision == 64 ) { 69 roundIncrement = UINT64_C( 0x0000000000000400 ); 70 roundMask = UINT64_C( 0x00000000000007FF ); 71 } else if ( roundingPrecision == 32 ) { 72 roundIncrement = UINT64_C( 0x0000008000000000 ); 73 roundMask = UINT64_C( 0x000000FFFFFFFFFF ); 74 } else { 75 goto precision80; 76 } 77 /*------------------------------------------------------------------------ 78 *------------------------------------------------------------------------*/ 79 if ( extSigPtr[indexWordLo( 3 )] ) sig |= 1; 80 if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) { 81 roundIncrement = 82 (roundingMode 83 == (sign ? softfloat_round_min : softfloat_round_max)) 84 ? roundMask 85 : 0; 86 } 87 roundBits = sig & roundMask; 88 /*------------------------------------------------------------------------ 89 *------------------------------------------------------------------------*/ 90 if ( 0x7FFD <= (uint32_t) (exp - 1) ) { 91 if ( exp <= 0 ) { 92 isTiny = 93 (softfloat_detectTininess 94 == softfloat_tininess_beforeRounding) 95 || (exp < 0) 96 || (sig <= (uint64_t) (sig + roundIncrement)); 97 sig = softfloat_shiftRightJam64( sig, 1 - exp ); 98 roundBits = sig & roundMask; 99 if ( roundBits ) { 100 if ( isTiny ) softfloat_raiseFlags( softfloat_flag_underflow ); 101 softfloat_exceptionFlags |= softfloat_flag_inexact; 102 } 103 sig += roundIncrement; 104 exp = ((sig & UINT64_C( 0x8000000000000000 )) != 0); 105 roundIncrement = roundMask + 1; 106 if ( roundNearEven && (roundBits<<1 == roundIncrement) ) { 107 roundMask |= roundIncrement; 108 } 109 sig &= ~roundMask; 110 goto packReturn; 111 } 112 if ( 113 (0x7FFE < exp) 114 || ((exp == 0x7FFE) && ((uint64_t) (sig + roundIncrement) < sig)) 115 ) { 116 goto overflow; 117 } 118 } 119 /*------------------------------------------------------------------------ 120 *------------------------------------------------------------------------*/ 121 if ( roundBits ) softfloat_exceptionFlags |= softfloat_flag_inexact; 122 sig += roundIncrement; 123 if ( sig < roundIncrement ) { 124 ++exp; 125 sig = UINT64_C( 0x8000000000000000 ); 126 } 127 roundIncrement = roundMask + 1; 128 if ( roundNearEven && (roundBits<<1 == roundIncrement) ) { 129 roundMask |= roundIncrement; 130 } 131 sig &= ~roundMask; 132 goto packReturn; 133 /*------------------------------------------------------------------------ 134 *------------------------------------------------------------------------*/ 135 precision80: 136 sigExtra = extSigPtr[indexWordLo( 3 )]; 137 doIncrement = (0x80000000 <= sigExtra); 138 if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) { 139 doIncrement = 140 (roundingMode 141 == (sign ? softfloat_round_min : softfloat_round_max)) 142 && sigExtra; 143 } 144 /*------------------------------------------------------------------------ 145 *------------------------------------------------------------------------*/ 146 if ( 0x7FFD <= (uint32_t) (exp - 1) ) { 147 /*-------------------------------------------------------------------- 148 *--------------------------------------------------------------------*/ 149 if ( exp <= 0 ) { 150 isTiny = 151 (softfloat_detectTininess 152 == softfloat_tininess_beforeRounding) 153 || (exp < 0) 154 || ! doIncrement 155 || (sig < UINT64_C( 0xFFFFFFFFFFFFFFFF )); 156 softfloat_shiftRightJam96M( extSigPtr, 1 - exp, extSigPtr ); 157 sigExtra = extSigPtr[indexWordLo( 3 )]; 158 if ( sigExtra ) { 159 if ( isTiny ) softfloat_raiseFlags( softfloat_flag_underflow ); 160 softfloat_exceptionFlags |= softfloat_flag_inexact; 161 } 162 doIncrement = (0x80000000 <= sigExtra); 163 if ( 164 ! roundNearEven 165 && (roundingMode != softfloat_round_near_maxMag) 166 ) { 167 doIncrement = 168 (roundingMode 169 == (sign ? softfloat_round_min : softfloat_round_max)) 170 && sigExtra; 171 } 172 exp = 0; 173 sig = 174 (uint64_t) extSigPtr[indexWord( 3, 2 )]<<32 175 | extSigPtr[indexWord( 3, 1 )]; 176 if ( doIncrement ) { 177 ++sig; 178 sig &= ~(uint64_t) (! (sigExtra & 0x7FFFFFFF) & roundNearEven); 179 exp = ((sig & UINT64_C( 0x8000000000000000 )) != 0); 180 } 181 goto packReturn; 182 } 183 /*-------------------------------------------------------------------- 184 *--------------------------------------------------------------------*/ 185 if ( 186 (0x7FFE < exp) 187 || ((exp == 0x7FFE) && (sig == UINT64_C( 0xFFFFFFFFFFFFFFFF )) 188 && doIncrement) 189 ) { 190 roundMask = 0; 191 overflow: 192 softfloat_raiseFlags( 193 softfloat_flag_overflow | softfloat_flag_inexact ); 194 if ( 195 roundNearEven 196 || (roundingMode == softfloat_round_near_maxMag) 197 || (roundingMode 198 == (sign ? softfloat_round_min : softfloat_round_max)) 199 ) { 200 exp = 0x7FFF; 201 sig = UINT64_C( 0x8000000000000000 ); 202 } else { 203 exp = 0x7FFE; 204 sig = ~roundMask; 205 } 206 goto packReturn; 207 } 208 } 209 /*------------------------------------------------------------------------ 210 *------------------------------------------------------------------------*/ 211 if ( sigExtra ) softfloat_exceptionFlags |= softfloat_flag_inexact; 212 if ( doIncrement ) { 213 ++sig; 214 if ( ! sig ) { 215 ++exp; 216 sig = UINT64_C( 0x8000000000000000 ); 217 } else { 218 sig &= ~(uint64_t) (! (sigExtra & 0x7FFFFFFF) & roundNearEven); 219 } 220 } 221 /*------------------------------------------------------------------------ 222 *------------------------------------------------------------------------*/ 223 packReturn: 224 zSPtr->signExp = packToExtF80UI64( sign, exp ); 225 zSPtr->signif = sig; 226 227 } 228 229