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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/s_subMagsF128.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"
+
+float128_t
+ softfloat_subMagsF128(
+ uint_fast64_t uiA64,
+ uint_fast64_t uiA0,
+ uint_fast64_t uiB64,
+ uint_fast64_t uiB0,
+ bool signZ
+ )
+{
+ int_fast32_t expA;
+ struct uint128 sigA;
+ int_fast32_t expB;
+ struct uint128 sigB, sigZ;
+ int_fast32_t expDiff, expZ;
+ struct uint128 uiZ;
+ union ui128_f128 uZ;
+
+ expA = expF128UI64( uiA64 );
+ sigA.v64 = fracF128UI64( uiA64 );
+ sigA.v0 = uiA0;
+ expB = expF128UI64( uiB64 );
+ sigB.v64 = fracF128UI64( uiB64 );
+ sigB.v0 = uiB0;
+ sigA = softfloat_shortShiftLeft128( sigA.v64, sigA.v0, 4 );
+ sigB = softfloat_shortShiftLeft128( sigB.v64, sigB.v0, 4 );
+ expDiff = expA - expB;
+ if ( 0 < expDiff ) goto expABigger;
+ if ( expDiff < 0 ) goto expBBigger;
+ if ( expA == 0x7FFF ) {
+ if ( sigA.v64 | sigA.v0 | sigB.v64 | sigB.v0 ) goto propagateNaN;
+ softfloat_raiseFlags( softfloat_flag_invalid );
+ uiZ.v64 = defaultNaNF128UI64;
+ uiZ.v0 = defaultNaNF128UI0;
+ goto uiZ;
+ }
+ expZ = expA;
+ if ( ! expZ ) expZ = 1;
+ if ( sigB.v64 < sigA.v64 ) goto aBigger;
+ if ( sigA.v64 < sigB.v64 ) goto bBigger;
+ if ( sigB.v0 < sigA.v0 ) goto aBigger;
+ if ( sigA.v0 < sigB.v0 ) goto bBigger;
+ uiZ.v64 =
+ packToF128UI64(
+ (softfloat_roundingMode == softfloat_round_min), 0, 0 );
+ uiZ.v0 = 0;
+ goto uiZ;
+ expBBigger:
+ if ( expB == 0x7FFF ) {
+ if ( sigB.v64 | sigB.v0 ) goto propagateNaN;
+ uiZ.v64 = packToF128UI64( signZ ^ 1, 0x7FFF, 0 );
+ uiZ.v0 = 0;
+ goto uiZ;
+ }
+ if ( expA ) {
+ sigA.v64 |= UINT64_C( 0x0010000000000000 );
+ } else {
+ ++expDiff;
+ if ( ! expDiff ) goto newlyAlignedBBigger;
+ }
+ sigA = softfloat_shiftRightJam128( sigA.v64, sigA.v0, -expDiff );
+ newlyAlignedBBigger:
+ expZ = expB;
+ sigB.v64 |= UINT64_C( 0x0010000000000000 );
+ bBigger:
+ signZ ^= 1;
+ sigZ = softfloat_sub128( sigB.v64, sigB.v0, sigA.v64, sigA.v0 );
+ goto normRoundPack;
+ expABigger:
+ if ( expA == 0x7FFF ) {
+ if ( sigA.v64 | sigA.v0 ) goto propagateNaN;
+ uiZ.v64 = uiA64;
+ uiZ.v0 = uiA0;
+ goto uiZ;
+ }
+ if ( expB ) {
+ sigB.v64 |= UINT64_C( 0x0010000000000000 );
+ } else {
+ --expDiff;
+ if ( ! expDiff ) goto newlyAlignedABigger;
+ }
+ sigB = softfloat_shiftRightJam128( sigB.v64, sigB.v0, expDiff );
+ newlyAlignedABigger:
+ expZ = expA;
+ sigA.v64 |= UINT64_C( 0x0010000000000000 );
+ aBigger:
+ sigZ = softfloat_sub128( sigA.v64, sigA.v0, sigB.v64, sigB.v0 );
+ normRoundPack:
+ return softfloat_normRoundPackToF128( signZ, expZ - 5, sigZ.v64, sigZ.v0 );
+ propagateNaN:
+ uiZ = softfloat_propagateNaNF128UI( uiA64, uiA0, uiB64, uiB0 );
+ uiZ:
+ uZ.ui = uiZ;
+ return uZ.f;
+
+}
+