1 2 /*============================================================================ 3 4 This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic 5 Package, Release 3a, by John R. Hauser. 6 7 Copyright 2011, 2012, 2013, 2014 The Regents of the University of California. 8 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 extFloat80_t 45 extF80_roundToInt( extFloat80_t a, uint_fast8_t roundingMode, bool exact ) 46 { 47 union { struct extFloat80M s; extFloat80_t f; } uA; 48 uint_fast16_t uiA64, signUI64; 49 int_fast32_t exp; 50 uint_fast64_t sigA; 51 uint_fast16_t uiZ64; 52 uint_fast64_t sigZ; 53 struct exp32_sig64 normExpSig; 54 struct uint128 uiZ; 55 uint_fast64_t lastBitMask, roundBitsMask; 56 union { struct extFloat80M s; extFloat80_t f; } uZ; 57 58 /*------------------------------------------------------------------------ 59 *------------------------------------------------------------------------*/ 60 uA.f = a; 61 uiA64 = uA.s.signExp; 62 signUI64 = uiA64 & packToExtF80UI64( 1, 0 ); 63 exp = expExtF80UI64( uiA64 ); 64 sigA = uA.s.signif; 65 /*------------------------------------------------------------------------ 66 *------------------------------------------------------------------------*/ 67 if ( ! (sigA & UINT64_C( 0x8000000000000000 )) && (exp != 0x7FFF) ) { 68 if ( ! sigA ) { 69 uiZ64 = signUI64; 70 sigZ = 0; 71 goto uiZ; 72 } 73 normExpSig = softfloat_normSubnormalExtF80Sig( sigA ); 74 exp += normExpSig.exp; 75 sigA = normExpSig.sig; 76 } 77 /*------------------------------------------------------------------------ 78 *------------------------------------------------------------------------*/ 79 if ( 0x403E <= exp ) { 80 if ( exp == 0x7FFF ) { 81 if ( sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) { 82 uiZ = softfloat_propagateNaNExtF80UI( uiA64, sigA, 0, 0 ); 83 uiZ64 = uiZ.v64; 84 sigZ = uiZ.v0; 85 goto uiZ; 86 } 87 sigZ = UINT64_C( 0x8000000000000000 ); 88 } else { 89 sigZ = sigA; 90 } 91 uiZ64 = signUI64 | exp; 92 goto uiZ; 93 } 94 if ( exp <= 0x3FFE ) { 95 if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact; 96 switch ( roundingMode ) { 97 case softfloat_round_near_even: 98 if ( ! (sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF )) ) break; 99 case softfloat_round_near_maxMag: 100 if ( exp == 0x3FFE ) goto mag1; 101 break; 102 case softfloat_round_min: 103 if ( signUI64 ) goto mag1; 104 break; 105 case softfloat_round_max: 106 if ( ! signUI64 ) goto mag1; 107 break; 108 } 109 uiZ64 = signUI64; 110 sigZ = 0; 111 goto uiZ; 112 mag1: 113 uiZ64 = signUI64 | 0x3FFF; 114 sigZ = UINT64_C( 0x8000000000000000 ); 115 goto uiZ; 116 } 117 /*------------------------------------------------------------------------ 118 *------------------------------------------------------------------------*/ 119 uiZ64 = signUI64 | exp; 120 lastBitMask = (uint_fast64_t) 1<<(0x403E - exp); 121 roundBitsMask = lastBitMask - 1; 122 sigZ = sigA; 123 if ( roundingMode == softfloat_round_near_maxMag ) { 124 sigZ += lastBitMask>>1; 125 } else if ( roundingMode == softfloat_round_near_even ) { 126 sigZ += lastBitMask>>1; 127 if ( ! (sigZ & roundBitsMask) ) sigZ &= ~lastBitMask; 128 } else if ( roundingMode != softfloat_round_minMag ) { 129 if ( (signUI64 != 0) ^ (roundingMode == softfloat_round_max) ) { 130 sigZ += roundBitsMask; 131 } 132 } 133 sigZ &= ~roundBitsMask; 134 if ( ! sigZ ) { 135 ++uiZ64; 136 sigZ = UINT64_C( 0x8000000000000000 ); 137 } 138 if ( exact && (sigZ != sigA) ) { 139 softfloat_exceptionFlags |= softfloat_flag_inexact; 140 } 141 uiZ: 142 uZ.s.signExp = uiZ64; 143 uZ.s.signif = sigZ; 144 return uZ.f; 145 146 } 147 148