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 float64_t softfloat_subMagsF64(uint_fast64_t uiA,uint_fast64_t uiB,bool signZ)45 softfloat_subMagsF64( uint_fast64_t uiA, uint_fast64_t uiB, bool signZ ) 46 { 47 int_fast16_t expA; 48 uint_fast64_t sigA; 49 int_fast16_t expB; 50 uint_fast64_t sigB; 51 int_fast16_t expDiff; 52 uint_fast64_t uiZ; 53 int_fast64_t sigDiff; 54 int_fast8_t shiftDist; 55 int_fast16_t expZ; 56 uint_fast64_t sigZ; 57 union ui64_f64 uZ; 58 59 /*------------------------------------------------------------------------ 60 *------------------------------------------------------------------------*/ 61 expA = expF64UI( uiA ); 62 sigA = fracF64UI( uiA ); 63 expB = expF64UI( uiB ); 64 sigB = fracF64UI( uiB ); 65 /*------------------------------------------------------------------------ 66 *------------------------------------------------------------------------*/ 67 expDiff = expA - expB; 68 if ( ! expDiff ) { 69 /*-------------------------------------------------------------------- 70 *--------------------------------------------------------------------*/ 71 if ( expA == 0x7FF ) { 72 if ( sigA | sigB ) goto propagateNaN; 73 softfloat_raiseFlags( softfloat_flag_invalid ); 74 uiZ = defaultNaNF64UI; 75 goto uiZ; 76 } 77 sigDiff = sigA - sigB; 78 if ( ! sigDiff ) { 79 uiZ = 80 packToF64UI( 81 (softfloat_roundingMode == softfloat_round_min), 0, 0 ); 82 goto uiZ; 83 } 84 if ( expA ) --expA; 85 if ( sigDiff < 0 ) { 86 signZ = ! signZ; 87 sigDiff = -sigDiff; 88 } 89 shiftDist = softfloat_countLeadingZeros64( sigDiff ) - 11; 90 expZ = expA - shiftDist; 91 if ( expZ < 0 ) { 92 shiftDist = expA; 93 expZ = 0; 94 } 95 uiZ = packToF64UI( signZ, expZ, sigDiff<<shiftDist ); 96 goto uiZ; 97 } else { 98 /*-------------------------------------------------------------------- 99 *--------------------------------------------------------------------*/ 100 sigA <<= 10; 101 sigB <<= 10; 102 if ( expDiff < 0 ) { 103 /*---------------------------------------------------------------- 104 *----------------------------------------------------------------*/ 105 signZ = ! signZ; 106 if ( expB == 0x7FF ) { 107 if ( sigB ) goto propagateNaN; 108 uiZ = packToF64UI( signZ, 0x7FF, 0 ); 109 goto uiZ; 110 } 111 sigA += expA ? UINT64_C( 0x4000000000000000 ) : sigA; 112 sigA = softfloat_shiftRightJam64( sigA, -expDiff ); 113 sigB |= UINT64_C( 0x4000000000000000 ); 114 expZ = expB; 115 sigZ = sigB - sigA; 116 } else { 117 /*---------------------------------------------------------------- 118 *----------------------------------------------------------------*/ 119 if ( expA == 0x7FF ) { 120 if ( sigA ) goto propagateNaN; 121 uiZ = uiA; 122 goto uiZ; 123 } 124 sigB += expB ? UINT64_C( 0x4000000000000000 ) : sigB; 125 sigB = softfloat_shiftRightJam64( sigB, expDiff ); 126 sigA |= UINT64_C( 0x4000000000000000 ); 127 expZ = expA; 128 sigZ = sigA - sigB; 129 } 130 return softfloat_normRoundPackToF64( signZ, expZ - 1, sigZ ); 131 } 132 /*------------------------------------------------------------------------ 133 *------------------------------------------------------------------------*/ 134 propagateNaN: 135 uiZ = softfloat_propagateNaNF64UI( uiA, uiB ); 136 uiZ: 137 uZ.ui = uiZ; 138 return uZ.f; 139 140 } 141 142