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 softfloat_subMagsExtF80( 46 uint_fast16_t uiA64, 47 uint_fast64_t uiA0, 48 uint_fast16_t uiB64, 49 uint_fast64_t uiB0, 50 bool signZ 51 ) 52 { 53 int_fast32_t expA; 54 uint_fast64_t sigA; 55 int_fast32_t expB; 56 uint_fast64_t sigB; 57 int_fast32_t expDiff; 58 uint_fast16_t uiZ64; 59 uint_fast64_t uiZ0; 60 int_fast32_t expZ; 61 uint_fast64_t sigExtra; 62 struct uint128 sig128, uiZ; 63 union { struct extFloat80M s; extFloat80_t f; } uZ; 64 65 /*------------------------------------------------------------------------ 66 *------------------------------------------------------------------------*/ 67 expA = expExtF80UI64( uiA64 ); 68 sigA = uiA0; 69 expB = expExtF80UI64( uiB64 ); 70 sigB = uiB0; 71 /*------------------------------------------------------------------------ 72 *------------------------------------------------------------------------*/ 73 expDiff = expA - expB; 74 if ( 0 < expDiff ) goto expABigger; 75 if ( expDiff < 0 ) goto expBBigger; 76 if ( expA == 0x7FFF ) { 77 if ( (sigA | sigB) & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) { 78 goto propagateNaN; 79 } 80 softfloat_raiseFlags( softfloat_flag_invalid ); 81 uiZ64 = defaultNaNExtF80UI64; 82 uiZ0 = defaultNaNExtF80UI0; 83 goto uiZ; 84 } 85 /*------------------------------------------------------------------------ 86 *------------------------------------------------------------------------*/ 87 expZ = expA; 88 if ( ! expZ ) expZ = 1; 89 sigExtra = 0; 90 if ( sigB < sigA ) goto aBigger; 91 if ( sigA < sigB ) goto bBigger; 92 uiZ64 = 93 packToExtF80UI64( (softfloat_roundingMode == softfloat_round_min), 0 ); 94 uiZ0 = 0; 95 goto uiZ; 96 /*------------------------------------------------------------------------ 97 *------------------------------------------------------------------------*/ 98 expBBigger: 99 if ( expB == 0x7FFF ) { 100 if ( sigB & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) goto propagateNaN; 101 uiZ64 = packToExtF80UI64( signZ ^ 1, 0x7FFF ); 102 uiZ0 = UINT64_C( 0x8000000000000000 ); 103 goto uiZ; 104 } 105 if ( ! expA ) { 106 ++expDiff; 107 sigExtra = 0; 108 if ( ! expDiff ) goto newlyAlignedBBigger; 109 } 110 sig128 = softfloat_shiftRightJam128( sigA, 0, -expDiff ); 111 sigA = sig128.v64; 112 sigExtra = sig128.v0; 113 newlyAlignedBBigger: 114 expZ = expB; 115 bBigger: 116 signZ ^= 1; 117 sig128 = softfloat_sub128( sigB, 0, sigA, sigExtra ); 118 goto normRoundPack; 119 /*------------------------------------------------------------------------ 120 *------------------------------------------------------------------------*/ 121 expABigger: 122 if ( expA == 0x7FFF ) { 123 if ( sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) goto propagateNaN; 124 uiZ64 = uiA64; 125 uiZ0 = uiA0; 126 goto uiZ; 127 } 128 if ( ! expB ) { 129 --expDiff; 130 sigExtra = 0; 131 if ( ! expDiff ) goto newlyAlignedABigger; 132 } 133 sig128 = softfloat_shiftRightJam128( sigB, 0, expDiff ); 134 sigB = sig128.v64; 135 sigExtra = sig128.v0; 136 newlyAlignedABigger: 137 expZ = expA; 138 aBigger: 139 sig128 = softfloat_sub128( sigA, 0, sigB, sigExtra ); 140 /*------------------------------------------------------------------------ 141 *------------------------------------------------------------------------*/ 142 normRoundPack: 143 return 144 softfloat_normRoundPackToExtF80( 145 signZ, expZ, sig128.v64, sig128.v0, extF80_roundingPrecision ); 146 /*------------------------------------------------------------------------ 147 *------------------------------------------------------------------------*/ 148 propagateNaN: 149 uiZ = softfloat_propagateNaNExtF80UI( uiA64, uiA0, uiB64, uiB0 ); 150 uiZ64 = uiZ.v64; 151 uiZ0 = uiZ.v0; 152 uiZ: 153 uZ.s.signExp = uiZ64; 154 uZ.s.signif = uiZ0; 155 return uZ.f; 156 157 } 158 159