124 lines
5.0 KiB
C++
124 lines
5.0 KiB
C++
/*============================================================================
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This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
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Package, Release 3e, by John R. Hauser.
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Copyright 2011, 2012, 2013, 2014, 2017 The Regents of the University of
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California. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright notice,
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this list of conditions, and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions, and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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3. Neither the name of the University nor the names of its contributors may
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be used to endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
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EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
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DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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=============================================================================*/
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#include <stdint.h>
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#include "internals.h"
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#include "specialize.h"
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#include "softfloat.h"
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extFloat80_t
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extF80_roundToInt(extFloat80_t a, uint8_t roundingMode, bool exact, struct softfloat_status_t *status)
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{
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uint16_t uiA64, signUI64;
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int32_t exp;
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uint64_t sigA;
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uint16_t uiZ64;
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uint64_t sigZ;
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uint64_t lastBitMask, roundBitsMask;
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// handle unsupported extended double-precision floating encodings
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if (extF80_isUnsupported(a)) {
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softfloat_raiseFlags(status, softfloat_flag_invalid);
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return packToExtF80_twoargs(defaultNaNExtF80UI64, defaultNaNExtF80UI0);
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uiA64 = a.signExp;
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signUI64 = uiA64 & packToExtF80UI64(1, 0);
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exp = expExtF80UI64(uiA64);
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sigA = a.signif;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (0x403E <= exp) {
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if ((exp == 0x7FFF) && (uint64_t) (sigA<<1)) {
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return softfloat_propagateNaNExtF80UI(uiA64, sigA, 0, 0, status);
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}
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return a;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (exp <= 0x3FFE) {
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if (! exp) {
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if ((sigA<<1) == 0) return a;
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softfloat_raiseFlags(status, softfloat_flag_denormal);
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}
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if (exact) softfloat_raiseFlags(status, softfloat_flag_inexact);
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switch (roundingMode) {
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case softfloat_round_near_even:
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if (!(sigA & UINT64_C(0x7FFFFFFFFFFFFFFF))) break;
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case softfloat_round_near_maxMag:
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if (exp == 0x3FFE) goto mag1;
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break;
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case softfloat_round_min:
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if (signUI64) goto mag1;
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break;
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case softfloat_round_max:
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if (!signUI64) goto mag1;
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break;
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}
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return packToExtF80(signUI64, 0, 0);
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mag1:
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softfloat_setRoundingUp(status);
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return packToExtF80(signUI64, 0x3FFF, UINT64_C(0x8000000000000000));
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uiZ64 = signUI64 | exp;
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lastBitMask = (uint64_t) 1<<(0x403E - exp);
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roundBitsMask = lastBitMask - 1;
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sigZ = sigA;
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if (roundingMode == softfloat_round_near_maxMag) {
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sigZ += lastBitMask>>1;
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} else if (roundingMode == softfloat_round_near_even) {
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sigZ += lastBitMask>>1;
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if (!(sigZ & roundBitsMask)) sigZ &= ~lastBitMask;
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} else if (roundingMode == (signUI64 ? softfloat_round_min : softfloat_round_max)) {
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sigZ += roundBitsMask;
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}
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sigZ &= ~roundBitsMask;
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if (!sigZ) {
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++uiZ64;
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sigZ = UINT64_C(0x8000000000000000);
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softfloat_setRoundingUp(status);
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}
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if (sigZ != sigA) {
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if (exact) softfloat_raiseFlags(status, softfloat_flag_inexact);
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if (sigZ > sigA)
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softfloat_setRoundingUp(status);
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}
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return packToExtF80_twoargs(uiZ64, sigZ);
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}
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