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 The Regents of the University of California. 9 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 "specialize.h" 43 #include "softfloat.h" 44 45 float64_t softfloat_subMagsF64(uint_fast64_t uiA,uint_fast64_t uiB,bool signZ)46 softfloat_subMagsF64( uint_fast64_t uiA, uint_fast64_t uiB, bool signZ ) 47 { 48 int_fast16_t expA; 49 uint_fast64_t sigA; 50 int_fast16_t expB; 51 uint_fast64_t sigB; 52 int_fast16_t expDiff; 53 uint_fast64_t uiZ; 54 int_fast16_t expZ; 55 uint_fast64_t sigZ; 56 union ui64_f64 uZ; 57 58 expA = expF64UI( uiA ); 59 sigA = fracF64UI( uiA ); 60 expB = expF64UI( uiB ); 61 sigB = fracF64UI( uiB ); 62 expDiff = expA - expB; 63 sigA <<= 10; 64 sigB <<= 10; 65 if ( 0 < expDiff ) goto expABigger; 66 if ( expDiff < 0 ) goto expBBigger; 67 if ( expA == 0x7FF ) { 68 if ( sigA | sigB ) goto propagateNaN; 69 softfloat_raiseFlags( softfloat_flag_invalid ); 70 uiZ = defaultNaNF64UI; 71 goto uiZ; 72 } 73 if ( ! expA ) { 74 expA = 1; 75 expB = 1; 76 } 77 if ( sigB < sigA ) goto aBigger; 78 if ( sigA < sigB ) goto bBigger; 79 uiZ = packToF64UI( softfloat_roundingMode == softfloat_round_min, 0, 0 ); 80 goto uiZ; 81 expBBigger: 82 if ( expB == 0x7FF ) { 83 if ( sigB ) goto propagateNaN; 84 uiZ = packToF64UI( signZ ^ 1, 0x7FF, 0 ); 85 goto uiZ; 86 } 87 sigA += expA ? UINT64_C( 0x4000000000000000 ) : sigA; 88 sigA = softfloat_shiftRightJam64( sigA, -expDiff ); 89 sigB |= UINT64_C( 0x4000000000000000 ); 90 bBigger: 91 signZ ^= 1; 92 expZ = expB; 93 sigZ = sigB - sigA; 94 goto normRoundPack; 95 expABigger: 96 if ( expA == 0x7FF ) { 97 if ( sigA ) goto propagateNaN; 98 uiZ = uiA; 99 goto uiZ; 100 } 101 sigB += expB ? UINT64_C( 0x4000000000000000 ) : sigB; 102 sigB = softfloat_shiftRightJam64( sigB, expDiff ); 103 sigA |= UINT64_C( 0x4000000000000000 ); 104 aBigger: 105 expZ = expA; 106 sigZ = sigA - sigB; 107 normRoundPack: 108 return softfloat_normRoundPackToF64( signZ, expZ - 1, sigZ ); 109 propagateNaN: 110 uiZ = softfloat_propagateNaNF64UI( uiA, uiB ); 111 uiZ: 112 uZ.ui = uiZ; 113 return uZ.f; 114 115 } 116 117