113 lines
4.7 KiB
C
113 lines
4.7 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, 2015, 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 <stdbool.h>
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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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float16 f16_roundToInt(float16 a, uint8_t scale, uint8_t roundingMode, bool exact, struct softfloat_status_t *status)
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{
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int8_t exp;
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uint16_t frac;
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bool sign;
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uint16_t uiZ, lastBitMask, roundBitsMask;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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scale &= 0xF;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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exp = expF16UI(a);
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frac = fracF16UI(a);
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sign = signF16UI(a);
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (0x19 <= (exp + scale)) {
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if ((exp == 0x1F) && frac) {
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return softfloat_propagateNaNF16UI(a, 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 (softfloat_denormalsAreZeros(status)) {
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if (!exp) {
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frac = 0;
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a = packToF16UI(sign, 0, 0);
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}
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if ((exp + scale) <= 0xE) {
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if (!(exp | frac)) return a;
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if (exact) softfloat_raiseFlags(status, softfloat_flag_inexact);
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uiZ = packToF16UI(sign, 0, 0);
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switch (roundingMode) {
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case softfloat_round_near_even:
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if (!frac) break;
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case softfloat_round_near_maxMag:
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if ((exp + scale) == 0xE) uiZ |= packToF16UI(0, 0xF - scale, 0);
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break;
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case softfloat_round_min:
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if (uiZ) uiZ = packToF16UI(1, 0xF - scale, 0);
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break;
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case softfloat_round_max:
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if (!uiZ) uiZ = packToF16UI(0, 0xF - scale, 0);
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break;
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}
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return uiZ;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uiZ = a;
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lastBitMask = (uint16_t) 1<<(0x19 - exp - scale);
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roundBitsMask = lastBitMask - 1;
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if (roundingMode == softfloat_round_near_maxMag) {
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uiZ += lastBitMask>>1;
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} else if (roundingMode == softfloat_round_near_even) {
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uiZ += lastBitMask>>1;
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if (!(uiZ & roundBitsMask)) uiZ &= ~lastBitMask;
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} else if (roundingMode == (signF16UI(uiZ) ? softfloat_round_min : softfloat_round_max)) {
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uiZ += roundBitsMask;
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}
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uiZ &= ~roundBitsMask;
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if (uiZ != a) {
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if (exact) softfloat_raiseFlags(status, softfloat_flag_inexact);
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}
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return uiZ;
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}
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