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authorJohn Hauser <jhauser@eecs.berkeley.edu>2014-11-28 19:49:28 -0800
committerJohn Hauser <jhauser@eecs.berkeley.edu>2014-11-28 19:49:28 -0800
commit8f59d925353145a65c09301dea6c47da1f1311b1 (patch)
treec55a81490cc411be6c812a5bfcc8fdc48296def9 /source/extF80M_rem.c
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First draft of RC for Release 3, to start review process.
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+
+/*============================================================================
+
+This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
+Package, Release 3, by John R. Hauser.
+
+Copyright 2011, 2012, 2013, 2014 The Regents of the University of California
+(Regents). All Rights Reserved. Redistribution and use in source and binary
+forms, with or without modification, are permitted provided that the following
+conditions are met:
+
+Redistributions of source code must retain the above copyright notice,
+this list of conditions, and the following two paragraphs of disclaimer.
+Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions, and the following two paragraphs of disclaimer in the
+documentation and/or other materials provided with the distribution. Neither
+the name of the Regents nor the names of its contributors may be used to
+endorse or promote products derived from this software without specific prior
+written permission.
+
+IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
+SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING
+OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS
+BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED
+TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED
+HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO OBLIGATION TO PROVIDE
+MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+
+=============================================================================*/
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "platform.h"
+#include "internals.h"
+#include "specialize.h"
+#include "softfloat.h"
+
+#ifdef SOFTFLOAT_FAST_INT64
+
+void
+ extF80M_rem(
+ const extFloat80_t *aPtr, const extFloat80_t *bPtr, extFloat80_t *zPtr )
+{
+
+ *zPtr = extF80_rem( *aPtr, *bPtr );
+
+}
+
+#else
+
+void
+ extF80M_rem(
+ const extFloat80_t *aPtr, const extFloat80_t *bPtr, extFloat80_t *zPtr )
+{
+ const struct extFloat80M *aSPtr, *bSPtr;
+ struct extFloat80M *zSPtr;
+ uint_fast16_t uiA64;
+ int32_t expA, expB;
+ uint64_t x64;
+ bool signRem;
+ uint64_t sigA;
+ int32_t expDiff;
+ uint32_t rem[3], x[3], sig32B, q, recip32, rem2[3], *remPtr, *altRemPtr;
+ uint32_t *newRemPtr, wordMeanRem;
+
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ aSPtr = (const struct extFloat80M *) aPtr;
+ bSPtr = (const struct extFloat80M *) bPtr;
+ zSPtr = (struct extFloat80M *) zPtr;
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ uiA64 = aSPtr->signExp;
+ expA = expExtF80UI64( uiA64 );
+ expB = expExtF80UI64( bSPtr->signExp );
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ if ( (expA == 0x7FFF) || (expB == 0x7FFF) ) {
+ if ( softfloat_tryPropagateNaNExtF80M( aSPtr, bSPtr, zSPtr ) ) return;
+ if ( expA == 0x7FFF ) goto invalid;
+ /*--------------------------------------------------------------------
+ | If we get here, then argument b is an infinity and `expB' is 0x7FFF;
+ | Doubling `expB' is an easy way to ensure that `expDiff' later is
+ | less than -1, which will result in returning a canonicalized version
+ | of argument a.
+ *--------------------------------------------------------------------*/
+ expB += expB;
+ }
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ if ( ! expB ) expB = 1;
+ x64 = bSPtr->signif;
+ if ( ! (x64 & UINT64_C( 0x8000000000000000 )) ) {
+ if ( ! x64 ) goto invalid;
+ expB += softfloat_normExtF80SigM( &x64 );
+ }
+ signRem = signExtF80UI64( uiA64 );
+ if ( ! expA ) expA = 1;
+ sigA = aSPtr->signif;
+ if ( ! (sigA & UINT64_C( 0x8000000000000000 )) ) {
+ if ( ! sigA ) {
+ expA = 0;
+ goto copyA;
+ }
+ expA += softfloat_normExtF80SigM( &sigA );
+ }
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ expDiff = expA - expB;
+ if ( expDiff < -1 ) goto copyA;
+ rem[indexWord( 3, 2 )] = sigA>>34;
+ rem[indexWord( 3, 1 )] = sigA>>2;
+ rem[indexWord( 3, 0 )] = (uint32_t) sigA<<30;
+ x[indexWord( 3, 0 )] = (uint32_t) x64<<30;
+ sig32B = x64>>32;
+ x64 >>= 2;
+ x[indexWord( 3, 2 )] = x64>>32;
+ x[indexWord( 3, 1 )] = x64;
+ if ( expDiff < 1 ) {
+ if ( expDiff ) {
+ --expB;
+ softfloat_add96M( x, x, x );
+ q = 0;
+ } else {
+ q = (softfloat_compare96M( x, rem ) <= 0);
+ if ( q ) softfloat_sub96M( rem, x, rem );
+ }
+ } else {
+ recip32 = softfloat_approxRecip32_1( sig32B );
+ expDiff -= 30;
+ for (;;) {
+ x64 = (uint64_t) rem[indexWordHi( 3 )] * recip32;
+ if ( expDiff < 0 ) break;
+ q = (x64 + 0x80000000)>>32;
+ softfloat_remStep96MBy32( rem, 29, x, q, rem );
+ if ( rem[indexWordHi( 3 )] & 0x80000000 ) {
+ softfloat_add96M( rem, x, rem );
+ }
+ expDiff -= 29;
+ }
+ /*--------------------------------------------------------------------
+ | (`expDiff' cannot be less than -29 here.)
+ *--------------------------------------------------------------------*/
+ q = (uint32_t) (x64>>32)>>(~expDiff & 31);
+ softfloat_remStep96MBy32( rem, expDiff + 30, x, q, rem );
+ if ( rem[indexWordHi( 3 )] & 0x80000000 ) {
+ remPtr = rem;
+ altRemPtr = rem2;
+ softfloat_add96M( remPtr, x, altRemPtr );
+ goto selectRem;
+ }
+ }
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ remPtr = rem;
+ altRemPtr = rem2;
+ do {
+ ++q;
+ newRemPtr = altRemPtr;
+ softfloat_sub96M( remPtr, x, newRemPtr );
+ altRemPtr = remPtr;
+ remPtr = newRemPtr;
+ } while ( ! (remPtr[indexWordHi( 3 )] & 0x80000000) );
+ selectRem:
+ softfloat_add96M( remPtr, altRemPtr, x );
+ wordMeanRem = x[indexWordHi( 3 )];
+ if (
+ (wordMeanRem & 0x80000000)
+ || (! wordMeanRem && (q & 1) && ! x[indexWord( 3, 0 )]
+ && ! x[indexWord( 3, 1 )])
+ ) {
+ remPtr = altRemPtr;
+ }
+ if ( remPtr[indexWordHi( 3 )] & 0x80000000 ) {
+ signRem = ! signRem;
+ softfloat_negX96M( remPtr );
+ }
+ softfloat_normRoundPackMToExtF80M( signRem, expB + 2, remPtr, 80, zSPtr );
+ return;
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ invalid:
+ softfloat_invalidExtF80M( zSPtr );
+ return;
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ copyA:
+ if ( expA < 1 ) {
+ sigA >>= 1 - expA;
+ expA = 0;
+ }
+ zSPtr->signExp = packToExtF80UI64( signRem, expA );
+ zSPtr->signif = sigA;
+
+}
+
+#endif
+
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