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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/f128_roundToInt.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
+ f128_roundToInt( float128_t a, uint_fast8_t roundingMode, bool exact )
+{
+ union ui128_f128 uA;
+ uint_fast64_t uiA64, uiA0;
+ int_fast32_t exp;
+ struct uint128 uiZ;
+ uint_fast64_t lastBitMask, roundBitsMask;
+ bool roundNearEven;
+ union ui128_f128 uZ;
+
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ uA.f = a;
+ uiA64 = uA.ui.v64;
+ uiA0 = uA.ui.v0;
+ exp = expF128UI64( uiA64 );
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ if ( 0x402F <= exp ) {
+ /*--------------------------------------------------------------------
+ *--------------------------------------------------------------------*/
+ if ( 0x406F <= exp ) {
+ if ( (exp == 0x7FFF) && (fracF128UI64( uiA64 ) | uiA0) ) {
+ uiZ = softfloat_propagateNaNF128UI( uiA64, uiA0, 0, 0 );
+ goto uiZ;
+ }
+ return a;
+ }
+ /*--------------------------------------------------------------------
+ *--------------------------------------------------------------------*/
+ lastBitMask = (uint_fast64_t) 2<<(0x406E - exp);
+ roundBitsMask = lastBitMask - 1;
+ uiZ.v64 = uiA64;
+ uiZ.v0 = uiA0;
+ roundNearEven = (roundingMode == softfloat_round_near_even);
+ if ( roundNearEven || (roundingMode == softfloat_round_near_maxMag) ) {
+ if ( exp == 0x402F ) {
+ if ( UINT64_C( 0x8000000000000000 ) <= uiZ.v0 ) {
+ ++uiZ.v64;
+ if (
+ roundNearEven
+ && (uiZ.v0 == UINT64_C( 0x8000000000000000 ))
+ ) {
+ uiZ.v64 &= ~1;
+ }
+ }
+ } else {
+ uiZ = softfloat_add128( uiZ.v64, uiZ.v0, 0, lastBitMask>>1 );
+ if ( roundNearEven && ! (uiZ.v0 & roundBitsMask) ) {
+ uiZ.v0 &= ~lastBitMask;
+ }
+ }
+ } else if ( roundingMode != softfloat_round_minMag ) {
+ if (
+ signF128UI64( uiZ.v64 ) ^ (roundingMode == softfloat_round_max)
+ ) {
+ uiZ = softfloat_add128( uiZ.v64, uiZ.v0, 0, roundBitsMask );
+ }
+ }
+ uiZ.v0 &= ~roundBitsMask;
+ } else {
+ /*--------------------------------------------------------------------
+ *--------------------------------------------------------------------*/
+ if ( exp < 0x3FFF ) {
+ if ( ! ((uiA64 & UINT64_C( 0x7FFFFFFFFFFFFFFF )) | uiA0) ) {
+ return a;
+ }
+ if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
+ uiZ.v64 = uiA64 & packToF128UI64( 1, 0, 0 );
+ uiZ.v0 = 0;
+ switch ( roundingMode ) {
+ case softfloat_round_near_even:
+ if ( ! (fracF128UI64( uiA64 ) | uiA0) ) break;
+ case softfloat_round_near_maxMag:
+ if ( exp == 0x3FFE ) uiZ.v64 |= packToF128UI64( 0, 0x3FFF, 0 );
+ break;
+ case softfloat_round_min:
+ if ( uiZ.v64 ) uiZ.v64 = packToF128UI64( 1, 0x3FFF, 0 );
+ break;
+ case softfloat_round_max:
+ if ( ! uiZ.v64 ) uiZ.v64 = packToF128UI64( 0, 0x3FFF, 0 );
+ break;
+ }
+ goto uiZ;
+ }
+ /*--------------------------------------------------------------------
+ *--------------------------------------------------------------------*/
+ uiZ.v64 = uiA64;
+ uiZ.v0 = 0;
+ lastBitMask = (uint_fast64_t) 1<<(0x402F - exp);
+ roundBitsMask = lastBitMask - 1;
+ if ( roundingMode == softfloat_round_near_maxMag ) {
+ uiZ.v64 += lastBitMask>>1;
+ } else if ( roundingMode == softfloat_round_near_even ) {
+ uiZ.v64 += lastBitMask>>1;
+ if ( ! ((uiZ.v64 & roundBitsMask) | uiA0) ) {
+ uiZ.v64 &= ~lastBitMask;
+ }
+ } else if ( roundingMode != softfloat_round_minMag ) {
+ if (
+ signF128UI64( uiZ.v64 ) ^ (roundingMode == softfloat_round_max)
+ ) {
+ uiZ.v64 = (uiZ.v64 | (uiA0 != 0)) + roundBitsMask;
+ }
+ }
+ uiZ.v64 &= ~roundBitsMask;
+ }
+ if ( exact && ((uiZ.v64 != uiA64) || (uiZ.v0 != uiA0)) ) {
+ softfloat_exceptionFlags |= softfloat_flag_inexact;
+ }
+ uiZ:
+ uZ.ui = uiZ;
+ return uZ.f;
+
+}
+
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