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 float32_t f32_sqrt( float32_t a ) 46 { 47 union ui32_f32 uA; 48 uint_fast32_t uiA; 49 bool signA; 50 int_fast16_t expA; 51 uint_fast32_t sigA, uiZ; 52 struct exp16_sig32 normExpSig; 53 int_fast16_t expZ; 54 uint_fast32_t sigZ, shiftedSigZ; 55 uint32_t negRem; 56 union ui32_f32 uZ; 57 58 /*------------------------------------------------------------------------ 59 *------------------------------------------------------------------------*/ 60 uA.f = a; 61 uiA = uA.ui; 62 signA = signF32UI( uiA ); 63 expA = expF32UI( uiA ); 64 sigA = fracF32UI( uiA ); 65 /*------------------------------------------------------------------------ 66 *------------------------------------------------------------------------*/ 67 if ( expA == 0xFF ) { 68 if ( sigA ) { 69 uiZ = softfloat_propagateNaNF32UI( uiA, 0 ); 70 goto uiZ; 71 } 72 if ( ! signA ) return a; 73 goto invalid; 74 } 75 /*------------------------------------------------------------------------ 76 *------------------------------------------------------------------------*/ 77 if ( signA ) { 78 if ( ! (expA | sigA) ) return a; 79 goto invalid; 80 } 81 /*------------------------------------------------------------------------ 82 *------------------------------------------------------------------------*/ 83 if ( ! expA ) { 84 if ( ! sigA ) return a; 85 normExpSig = softfloat_normSubnormalF32Sig( sigA ); 86 expA = normExpSig.exp; 87 sigA = normExpSig.sig; 88 } 89 /*------------------------------------------------------------------------ 90 *------------------------------------------------------------------------*/ 91 expZ = ((expA - 0x7F)>>1) + 0x7E; 92 expA &= 1; 93 sigA = (sigA | 0x00800000)<<8; 94 sigZ = 95 ((uint_fast64_t) sigA * softfloat_approxRecipSqrt32_1( expA, sigA )) 96 >>32; 97 if ( expA ) sigZ >>= 1; 98 sigZ += 2; 99 /*------------------------------------------------------------------------ 100 *------------------------------------------------------------------------*/ 101 if ( (sigZ & 0x3F) < 2 ) { 102 shiftedSigZ = sigZ>>2; 103 negRem = shiftedSigZ * shiftedSigZ; 104 sigZ = shiftedSigZ<<2; 105 if ( negRem & 0x80000000 ) { 106 sigZ |= 1; 107 } else { 108 if ( negRem ) --sigZ; 109 } 110 } 111 return softfloat_roundPackToF32( 0, expZ, sigZ ); 112 /*------------------------------------------------------------------------ 113 *------------------------------------------------------------------------*/ 114 invalid: 115 softfloat_raiseFlags( softfloat_flag_invalid ); 116 uiZ = defaultNaNF32UI; 117 uiZ: 118 uZ.ui = uiZ; 119 return uZ.f; 120 121 } 122 123