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 f32_rem( float32_t a, float32_t b ) 45 { 46 union ui32_f32 uA; 47 uint_fast32_t uiA; 48 bool signA; 49 int_fast16_t expA; 50 uint_fast32_t sigA; 51 union ui32_f32 uB; 52 uint_fast32_t uiB; 53 int_fast16_t expB; 54 uint_fast32_t sigB; 55 struct exp16_sig32 normExpSig; 56 uint32_t rem; 57 int_fast16_t expDiff; 58 uint32_t q, recip32, altRem, meanRem; 59 bool signRem; 60 uint_fast32_t uiZ; 61 union ui32_f32 uZ; 62 63 /*------------------------------------------------------------------------ 64 *------------------------------------------------------------------------*/ 65 uA.f = a; 66 uiA = uA.ui; 67 signA = signF32UI( uiA ); 68 expA = expF32UI( uiA ); 69 sigA = fracF32UI( uiA ); 70 uB.f = b; 71 uiB = uB.ui; 72 expB = expF32UI( uiB ); 73 sigB = fracF32UI( uiB ); 74 /*------------------------------------------------------------------------ 75 *------------------------------------------------------------------------*/ 76 if ( expA == 0xFF ) { 77 if ( sigA || ((expB == 0xFF) && sigB) ) goto propagateNaN; 78 goto invalid; 79 } 80 if ( expB == 0xFF ) { 81 if ( sigB ) goto propagateNaN; 82 return a; 83 } 84 /*------------------------------------------------------------------------ 85 *------------------------------------------------------------------------*/ 86 if ( ! expB ) { 87 if ( ! sigB ) goto invalid; 88 normExpSig = softfloat_normSubnormalF32Sig( sigB ); 89 expB = normExpSig.exp; 90 sigB = normExpSig.sig; 91 } 92 if ( ! expA ) { 93 if ( ! sigA ) return a; 94 normExpSig = softfloat_normSubnormalF32Sig( sigA ); 95 expA = normExpSig.exp; 96 sigA = normExpSig.sig; 97 } 98 /*------------------------------------------------------------------------ 99 *------------------------------------------------------------------------*/ 100 rem = sigA | 0x00800000; 101 sigB |= 0x00800000; 102 expDiff = expA - expB; 103 if ( expDiff < 1 ) { 104 if ( expDiff < -1 ) return a; 105 sigB <<= 6; 106 if ( expDiff ) { 107 rem <<= 5; 108 q = 0; 109 } else { 110 rem <<= 6; 111 q = (sigB <= rem); 112 if ( q ) rem -= sigB; 113 } 114 } else { 115 recip32 = softfloat_approxRecip32_1( sigB<<8 ); 116 /*-------------------------------------------------------------------- 117 | Changing the shift of `rem' here requires also changing the initial 118 | subtraction from `expDiff'. 119 *--------------------------------------------------------------------*/ 120 rem <<= 7; 121 expDiff -= 31; 122 /*-------------------------------------------------------------------- 123 | The scale of `sigB' affects how many bits are obtained during each 124 | cycle of the loop. Currently this is 29 bits per loop iteration, 125 | which is believed to be the maximum possible. 126 *--------------------------------------------------------------------*/ 127 sigB <<= 6; 128 for (;;) { 129 q = (rem * (uint_fast64_t) recip32)>>32; 130 if ( expDiff < 0 ) break; 131 rem = -(q * (uint32_t) sigB); 132 expDiff -= 29; 133 } 134 /*-------------------------------------------------------------------- 135 | (`expDiff' cannot be less than -30 here.) 136 *--------------------------------------------------------------------*/ 137 q >>= ~expDiff & 31; 138 rem = (rem<<(expDiff + 30)) - q * (uint32_t) sigB; 139 } 140 /*------------------------------------------------------------------------ 141 *------------------------------------------------------------------------*/ 142 do { 143 altRem = rem; 144 ++q; 145 rem -= sigB; 146 } while ( ! (rem & 0x80000000) ); 147 meanRem = rem + altRem; 148 if ( (meanRem & 0x80000000) || (! meanRem && (q & 1)) ) rem = altRem; 149 signRem = signA; 150 if ( 0x80000000 <= rem ) { 151 signRem = ! signRem; 152 rem = -rem; 153 } 154 return softfloat_normRoundPackToF32( signRem, expB, rem ); 155 /*------------------------------------------------------------------------ 156 *------------------------------------------------------------------------*/ 157 propagateNaN: 158 uiZ = softfloat_propagateNaNF32UI( uiA, uiB ); 159 goto uiZ; 160 invalid: 161 softfloat_raiseFlags( softfloat_flag_invalid ); 162 uiZ = defaultNaNF32UI; 163 uiZ: 164 uZ.ui = uiZ; 165 return uZ.f; 166 167 } 168 169