190 lines
6.9 KiB
C
190 lines
6.9 KiB
C
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/*============================================================================
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This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
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Package, Release 3e, by John R. Hauser.
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Copyright 2011, 2012, 2013, 2014 The Regents of the University of California.
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright notice,
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this list of conditions, and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions, and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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3. Neither the name of the University nor the names of its contributors may
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be used to endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
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EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
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DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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=============================================================================*/
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#include <stdbool.h>
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#include <stdint.h>
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#include "platform.h"
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#include "internals.h"
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#include "specialize.h"
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#include "softfloat.h"
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float64_t f64_rem( float64_t a, float64_t b )
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{
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union ui64_f64 uA;
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uint_fast64_t uiA;
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bool signA;
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int_fast16_t expA;
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uint_fast64_t sigA;
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union ui64_f64 uB;
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uint_fast64_t uiB;
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int_fast16_t expB;
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uint_fast64_t sigB;
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struct exp16_sig64 normExpSig;
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uint64_t rem;
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int_fast16_t expDiff;
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uint32_t q, recip32;
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uint_fast64_t q64;
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uint64_t altRem, meanRem;
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bool signRem;
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uint_fast64_t uiZ;
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union ui64_f64 uZ;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uA.f = a;
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uiA = uA.ui;
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signA = signF64UI( uiA );
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expA = expF64UI( uiA );
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sigA = fracF64UI( uiA );
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uB.f = b;
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uiB = uB.ui;
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expB = expF64UI( uiB );
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sigB = fracF64UI( uiB );
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( expA == 0x7FF ) {
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if ( sigA || ((expB == 0x7FF) && sigB) ) goto propagateNaN;
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goto invalid;
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}
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if ( expB == 0x7FF ) {
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if ( sigB ) goto propagateNaN;
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return a;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( expA < expB - 1 ) return a;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ( ! expB ) {
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if ( ! sigB ) goto invalid;
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normExpSig = softfloat_normSubnormalF64Sig( sigB );
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expB = normExpSig.exp;
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sigB = normExpSig.sig;
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}
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if ( ! expA ) {
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if ( ! sigA ) return a;
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normExpSig = softfloat_normSubnormalF64Sig( sigA );
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expA = normExpSig.exp;
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sigA = normExpSig.sig;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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rem = sigA | UINT64_C( 0x0010000000000000 );
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sigB |= UINT64_C( 0x0010000000000000 );
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expDiff = expA - expB;
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if ( expDiff < 1 ) {
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if ( expDiff < -1 ) return a;
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sigB <<= 9;
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if ( expDiff ) {
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rem <<= 8;
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q = 0;
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} else {
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rem <<= 9;
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q = (sigB <= rem);
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if ( q ) rem -= sigB;
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}
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} else {
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recip32 = softfloat_approxRecip32_1( sigB>>21 );
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/*--------------------------------------------------------------------
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| Changing the shift of `rem' here requires also changing the initial
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| subtraction from `expDiff'.
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*--------------------------------------------------------------------*/
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rem <<= 9;
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expDiff -= 30;
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/*--------------------------------------------------------------------
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| The scale of `sigB' affects how many bits are obtained during each
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| cycle of the loop. Currently this is 29 bits per loop iteration,
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| the maximum possible.
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*--------------------------------------------------------------------*/
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sigB <<= 9;
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for (;;) {
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q64 = (uint32_t) (rem>>32) * (uint_fast64_t) recip32;
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if ( expDiff < 0 ) break;
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q = (q64 + 0x80000000)>>32;
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#ifdef SOFTFLOAT_FAST_INT64
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rem <<= 29;
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#else
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rem = (uint_fast64_t) (uint32_t) (rem>>3)<<32;
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#endif
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rem -= q * (uint64_t) sigB;
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if ( rem & UINT64_C( 0x8000000000000000 ) ) rem += sigB;
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expDiff -= 29;
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}
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/*--------------------------------------------------------------------
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| (`expDiff' cannot be less than -29 here.)
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*--------------------------------------------------------------------*/
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q = (uint32_t) (q64>>32)>>(~expDiff & 31);
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rem = (rem<<(expDiff + 30)) - q * (uint64_t) sigB;
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if ( rem & UINT64_C( 0x8000000000000000 ) ) {
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altRem = rem + sigB;
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goto selectRem;
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}
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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do {
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altRem = rem;
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++q;
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rem -= sigB;
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} while ( ! (rem & UINT64_C( 0x8000000000000000 )) );
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selectRem:
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meanRem = rem + altRem;
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if (
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(meanRem & UINT64_C( 0x8000000000000000 )) || (! meanRem && (q & 1))
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) {
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rem = altRem;
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}
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signRem = signA;
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if ( rem & UINT64_C( 0x8000000000000000 ) ) {
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signRem = ! signRem;
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rem = -rem;
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}
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return softfloat_normRoundPackToF64( signRem, expB, rem );
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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propagateNaN:
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uiZ = softfloat_propagateNaNF64UI( uiA, uiB );
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goto uiZ;
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invalid:
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softfloat_raiseFlags( softfloat_flag_invalid );
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uiZ = defaultNaNF64UI;
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uiZ:
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uZ.ui = uiZ;
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return uZ.f;
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}
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