+/*============================================================================
+
+This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
+Package, Release 3a, by John R. Hauser.
+
+Copyright 2011, 2012, 2013, 2014 The Regents of the University of California.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ 1. Redistributions of source code must retain the above copyright notice,
+ this list of conditions, and the following disclaimer.
+
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+ this list of conditions, and the following disclaimer in the documentation
+ and/or other materials provided with the distribution.
+
+ 3. Neither the name of the University nor the names of its contributors may
+ be used to endorse or promote products derived from this software without
+ specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
+DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+=============================================================================*/
+
#include <stdbool.h>
#include <stdint.h>
#include "platform.h"
-#include "primitives.h"
#include "internals.h"
#include "specialize.h"
#include "softfloat.h"
uint_fast32_t sigA;
union ui32_f32 uB;
uint_fast32_t uiB;
- bool signB;
int_fast16_t expB;
uint_fast32_t sigB;
struct exp16_sig32 normExpSig;
+ uint32_t rem;
int_fast16_t expDiff;
- uint_fast32_t q;
- uint_fast64_t sigA64, sigB64, q64;
- uint_fast32_t alternateSigA;
- uint32_t sigMean;
- bool signZ;
+ uint32_t q, recip32, altRem, meanRem;
+ bool signRem;
uint_fast32_t uiZ;
union ui32_f32 uZ;
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
uA.f = a;
uiA = uA.ui;
signA = signF32UI( uiA );
- expA = expF32UI( uiA );
- sigA = fracF32UI( uiA );
+ expA = expF32UI( uiA );
+ sigA = fracF32UI( uiA );
uB.f = b;
uiB = uB.ui;
- signB = signF32UI( uiB );
expB = expF32UI( uiB );
sigB = fracF32UI( uiB );
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
if ( expA == 0xFF ) {
- if ( sigA || ( ( expB == 0xFF ) && sigB ) ) goto propagateNaN;
+ if ( sigA || ((expB == 0xFF) && sigB) ) goto propagateNaN;
goto invalid;
}
if ( expB == 0xFF ) {
if ( sigB ) goto propagateNaN;
return a;
}
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
if ( ! expB ) {
if ( ! sigB ) goto invalid;
normExpSig = softfloat_normSubnormalF32Sig( sigB );
expA = normExpSig.exp;
sigA = normExpSig.sig;
}
- expDiff = expA - expB;
- sigA |= 0x00800000;
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ rem = sigA | 0x00800000;
sigB |= 0x00800000;
- if ( expDiff < 32 ) {
- sigA <<= 8;
- sigB <<= 8;
- if ( expDiff < 0 ) {
- if ( expDiff < -1 ) return a;
- sigA >>= 1;
- }
- q = ( sigB <= sigA );
- if ( q ) sigA -= sigB;
- if ( 0 < expDiff ) {
- q = ( (uint_fast64_t) sigA<<32 ) / sigB;
- q >>= 32 - expDiff;
- sigB >>= 2;
- sigA = ( ( sigA>>1 )<<( expDiff - 1 ) ) - sigB * q;
+ expDiff = expA - expB;
+ if ( expDiff < 1 ) {
+ if ( expDiff < -1 ) return a;
+ sigB <<= 6;
+ if ( expDiff ) {
+ rem <<= 5;
+ q = 0;
} else {
- sigA >>= 2;
- sigB >>= 2;
+ rem <<= 6;
+ q = (sigB <= rem);
+ if ( q ) rem -= sigB;
}
} else {
- if ( sigB <= sigA ) sigA -= sigB;
- sigA64 = (uint_fast64_t) sigA<<40;
- sigB64 = (uint_fast64_t) sigB<<40;
- expDiff -= 64;
- while ( 0 < expDiff ) {
- q64 = softfloat_estimateDiv128To64( sigA64, 0, sigB64 );
- q64 = ( 2 < q64 ) ? q64 - 2 : 0;
- sigA64 = - ( ( sigB * q64 )<<38 );
- expDiff -= 62;
- }
- expDiff += 64;
- q64 = softfloat_estimateDiv128To64( sigA64, 0, sigB64 );
- q64 = ( 2 < q64 ) ? q64 - 2 : 0;
- q = q64>>( 64 - expDiff );
+ recip32 = softfloat_approxRecip32_1( sigB<<8 );
+ /*--------------------------------------------------------------------
+ | Changing the shift of `rem' here requires also changing the initial
+ | subtraction from `expDiff'.
+ *--------------------------------------------------------------------*/
+ rem <<= 7;
+ expDiff -= 31;
+ /*--------------------------------------------------------------------
+ | The scale of `sigB' affects how many bits are obtained during each
+ | cycle of the loop. Currently this is 29 bits per loop iteration,
+ | which is believed to be the maximum possible.
+ *--------------------------------------------------------------------*/
sigB <<= 6;
- sigA = ( ( sigA64>>33 )<<( expDiff - 1 ) ) - sigB * q;
+ for (;;) {
+ q = (rem * (uint_fast64_t) recip32)>>32;
+ if ( expDiff < 0 ) break;
+ rem = -(q * (uint32_t) sigB);
+ expDiff -= 29;
+ }
+ /*--------------------------------------------------------------------
+ | (`expDiff' cannot be less than -30 here.)
+ *--------------------------------------------------------------------*/
+ q >>= ~expDiff & 31;
+ rem = (rem<<(expDiff + 30)) - q * (uint32_t) sigB;
}
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
do {
- alternateSigA = sigA;
+ altRem = rem;
++q;
- sigA -= sigB;
- } while ( sigA < 0x80000000 );
- sigMean = sigA + alternateSigA;
- if ( ( 0x80000000 <= sigMean ) || ( ! sigMean && ( q & 1 ) ) ) {
- sigA = alternateSigA;
+ rem -= sigB;
+ } while ( ! (rem & 0x80000000) );
+ meanRem = rem + altRem;
+ if ( (meanRem & 0x80000000) || (! meanRem && (q & 1)) ) rem = altRem;
+ signRem = signA;
+ if ( 0x80000000 <= rem ) {
+ signRem = ! signRem;
+ rem = -rem;
}
- signZ = ( 0x80000000 <= sigA );
- if ( signZ ) sigA = - sigA;
- return softfloat_normRoundPackToF32( signA ^ signZ, expB, sigA );
+ return softfloat_normRoundPackToF32( signRem, expB, rem );
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
propagateNaN:
uiZ = softfloat_propagateNaNF32UI( uiA, uiB );
goto uiZ;
projects / riscv-isa-sim.git / blobdiff