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148 lines
5.5 KiB
C
148 lines
5.5 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 3, by John R. Hauser.
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Copyright 2011, 2012, 2013, 2014, 2015 The Regents of the University of
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California (Regents). All Rights Reserved. Redistribution and use in source
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and binary forms, with or without modification, are permitted provided that
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the following conditions are met:
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Redistributions of source code must retain the above copyright notice,
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this list of conditions, and the following two paragraphs of disclaimer.
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Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions, and the following two paragraphs of disclaimer in the
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documentation and/or other materials provided with the distribution. Neither
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the name of the Regents nor the names of its contributors may be used to
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endorse or promote products derived from this software without specific prior
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written permission.
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IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
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SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING
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OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS
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BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED
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TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED
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HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO OBLIGATION TO PROVIDE
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MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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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 "softfloat.h"
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float128_t
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softfloat_roundPackToF128(
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bool sign,
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int_fast32_t exp,
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uint_fast64_t sig64,
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uint_fast64_t sig0,
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uint_fast64_t sigExtra
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)
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{
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uint_fast8_t roundingMode;
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bool roundNearEven, doIncrement, isTiny;
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struct uint128_extra sig128Extra;
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uint_fast64_t uiZ64, uiZ0;
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struct uint128 sig128;
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union ui128_f128 uZ;
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roundingMode = softfloat_roundingMode;
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roundNearEven = (roundingMode == softfloat_round_near_even);
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doIncrement = (UINT64_C( 0x8000000000000000 ) <= sigExtra);
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if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) {
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doIncrement =
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(roundingMode
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== (sign ? softfloat_round_min : softfloat_round_max))
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&& sigExtra;
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}
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if ( 0x7FFD <= (uint32_t) exp ) {
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if ( exp < 0 ) {
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isTiny =
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(softfloat_detectTininess
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== softfloat_tininess_beforeRounding)
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|| (exp < -1)
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|| ! doIncrement
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|| softfloat_lt128(
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sig64,
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sig0,
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UINT64_C( 0x0001FFFFFFFFFFFF ),
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UINT64_C( 0xFFFFFFFFFFFFFFFF )
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);
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sig128Extra =
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softfloat_shiftRightJam128Extra( sig64, sig0, sigExtra, -exp );
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sig64 = sig128Extra.v.v64;
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sig0 = sig128Extra.v.v0;
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sigExtra = sig128Extra.extra;
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exp = 0;
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if ( isTiny && sigExtra ) {
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softfloat_raiseFlags( softfloat_flag_underflow );
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}
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doIncrement = (UINT64_C( 0x8000000000000000 ) <= sigExtra);
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if (
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! roundNearEven
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&& (roundingMode != softfloat_round_near_maxMag)
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) {
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doIncrement =
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(roundingMode
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== (sign ? softfloat_round_min : softfloat_round_max))
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&& sigExtra;
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}
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} else if (
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(0x7FFD < exp)
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|| ((exp == 0x7FFD)
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&& softfloat_eq128(
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sig64,
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sig0,
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UINT64_C( 0x0001FFFFFFFFFFFF ),
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UINT64_C( 0xFFFFFFFFFFFFFFFF )
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)
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&& doIncrement)
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) {
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softfloat_raiseFlags(
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softfloat_flag_overflow | softfloat_flag_inexact );
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if (
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roundNearEven
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|| (roundingMode == softfloat_round_near_maxMag)
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|| (roundingMode
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== (sign ? softfloat_round_min : softfloat_round_max))
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) {
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uiZ64 = packToF128UI64( sign, 0x7FFF, 0 );
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uiZ0 = 0;
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} else {
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uiZ64 =
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packToF128UI64(
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sign, 0x7FFE, UINT64_C( 0x0000FFFFFFFFFFFF ) );
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uiZ0 = UINT64_C( 0xFFFFFFFFFFFFFFFF );
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}
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goto uiZ;
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}
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}
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if ( sigExtra ) softfloat_exceptionFlags |= softfloat_flag_inexact;
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if ( doIncrement ) {
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sig128 = softfloat_add128( sig64, sig0, 0, 1 );
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sig64 = sig128.v64;
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sig0 =
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sig128.v0
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& ~(uint64_t)
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(! (sigExtra & UINT64_C( 0x7FFFFFFFFFFFFFFF ))
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& roundNearEven);
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} else {
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if ( ! (sig64 | sig0) ) exp = 0;
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}
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uiZ64 = packToF128UI64( sign, exp, sig64 );
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uiZ0 = sig0;
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uiZ:
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uZ.ui.v64 = uiZ64;
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uZ.ui.v0 = uiZ0;
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return uZ.f;
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}
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