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 float32_t 45 softfloat_subMagsF32( uint_fast32_t uiA, uint_fast32_t uiB, bool signZ ) 46 { 47 int_fast16_t expA; 48 uint_fast32_t sigA; 49 int_fast16_t expB; 50 uint_fast32_t sigB; 51 int_fast16_t expDiff; 52 uint_fast32_t uiZ; 53 int_fast16_t expZ; 54 uint_fast32_t sigZ; 55 union ui32_f32 uZ; 56 57 expA = expF32UI( uiA ); 58 sigA = fracF32UI( uiA ); 59 expB = expF32UI( uiB ); 60 sigB = fracF32UI( uiB ); 61 expDiff = expA - expB; 62 sigA <<= 7; 63 sigB <<= 7; 64 if ( 0 < expDiff ) goto expABigger; 65 if ( expDiff < 0 ) goto expBBigger; 66 if ( expA == 0xFF ) { 67 if ( sigA | sigB ) goto propagateNaN; 68 softfloat_raiseFlags( softfloat_flag_invalid ); 69 uiZ = defaultNaNF32UI; 70 goto uiZ; 71 } 72 if ( ! expA ) { 73 expA = 1; 74 expB = 1; 75 } 76 if ( sigB < sigA ) goto aBigger; 77 if ( sigA < sigB ) goto bBigger; 78 uiZ = packToF32UI( softfloat_roundingMode == softfloat_round_min, 0, 0 ); 79 goto uiZ; 80 expBBigger: 81 if ( expB == 0xFF ) { 82 if ( sigB ) goto propagateNaN; 83 uiZ = packToF32UI( signZ ^ 1, 0xFF, 0 ); 84 goto uiZ; 85 } 86 sigA += expA ? 0x40000000 : sigA; 87 sigA = softfloat_shiftRightJam32( sigA, -expDiff ); 88 sigB |= 0x40000000; 89 bBigger: 90 signZ ^= 1; 91 expZ = expB; 92 sigZ = sigB - sigA; 93 goto normRoundPack; 94 expABigger: 95 if ( expA == 0xFF ) { 96 if ( sigA ) goto propagateNaN; 97 uiZ = uiA; 98 goto uiZ; 99 } 100 sigB += expB ? 0x40000000 : sigB; 101 sigB = softfloat_shiftRightJam32( sigB, expDiff ); 102 sigA |= 0x40000000; 103 aBigger: 104 expZ = expA; 105 sigZ = sigA - sigB; 106 normRoundPack: 107 return softfloat_normRoundPackToF32( signZ, expZ - 1, sigZ ); 108 propagateNaN: 109 uiZ = softfloat_propagateNaNF32UI( uiA, uiB ); 110 uiZ: 111 uZ.ui = uiZ; 112 return uZ.f; 113 114 } 115 116