233 lines
9.0 KiB
C
233 lines
9.0 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, 2015 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 "primitives.h"
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#include "softfloat.h"
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#include "specialize.h"
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float16 f16_mulAdd(float16 a, float16 b, float16 c, uint8_t op, struct softfloat_status_t *status)
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{
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bool signA;
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int8_t expA;
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uint16_t sigA;
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bool signB;
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int8_t expB;
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uint16_t sigB;
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bool signC;
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int8_t expC;
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uint16_t sigC;
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bool signProd;
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uint16_t magBits, uiA, uiB, uiC, uiZ;
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struct exp8_sig16 normExpSig;
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int8_t expProd;
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uint32_t sigProd;
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bool signZ;
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int8_t expZ;
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uint16_t sigZ;
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int8_t expDiff;
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uint32_t sig32Z, sig32C;
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int8_t shiftDist;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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uiA = a;
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uiB = b;
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uiC = c;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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signA = signF16UI(uiA);
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expA = expF16UI(uiA);
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sigA = fracF16UI(uiA);
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signB = signF16UI(uiB);
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expB = expF16UI(uiB);
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sigB = fracF16UI(uiB);
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signC = signF16UI(uiC) ^ ((op & softfloat_mulAdd_subC) != 0);
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expC = expF16UI(uiC);
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sigC = fracF16UI(uiC);
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signProd = signA ^ signB ^ ((op & softfloat_mulAdd_subProd) != 0);
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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bool aisNaN = (expA == 0x1F) && sigA;
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bool bisNaN = (expB == 0x1F) && sigB;
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bool cisNaN = (expC == 0x1F) && sigC;
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if (aisNaN | bisNaN | cisNaN) {
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uiZ = (aisNaN | bisNaN) ? softfloat_propagateNaNF16UI(uiA, uiB, status) : 0;
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return softfloat_propagateNaNF16UI(uiZ, uiC, status);
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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 (!expA) sigA = 0;
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if (!expB) sigB = 0;
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if (!expC) sigC = 0;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (expA == 0x1F) {
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magBits = expB | sigB;
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goto infProdArg;
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}
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if (expB == 0x1F) {
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magBits = expA | sigA;
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goto infProdArg;
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}
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if (expC == 0x1F) {
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if ((sigA && !expA) || (sigB && !expB)) {
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softfloat_raiseFlags(status, softfloat_flag_denormal);
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}
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return packToF16UI(signC, 0x1F, 0);
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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if (! expA) {
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if (! sigA) goto zeroProd;
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softfloat_raiseFlags(status, softfloat_flag_denormal);
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normExpSig = softfloat_normSubnormalF16Sig(sigA);
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expA = normExpSig.exp;
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sigA = normExpSig.sig;
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}
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if (! expB) {
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if (! sigB) goto zeroProd;
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softfloat_raiseFlags(status, softfloat_flag_denormal);
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normExpSig = softfloat_normSubnormalF16Sig(sigB);
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expB = normExpSig.exp;
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sigB = normExpSig.sig;
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}
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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expProd = expA + expB - 0xE;
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sigA = (sigA | 0x0400)<<4;
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sigB = (sigB | 0x0400)<<4;
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sigProd = (uint32_t) sigA * sigB;
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if (sigProd < 0x20000000) {
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--expProd;
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sigProd <<= 1;
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}
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signZ = signProd;
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if (! expC) {
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if (! sigC) {
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expZ = expProd - 1;
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sigZ = sigProd>>15 | ((sigProd & 0x7FFF) != 0);
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goto roundPack;
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}
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softfloat_raiseFlags(status, softfloat_flag_denormal);
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normExpSig = softfloat_normSubnormalF16Sig(sigC);
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expC = normExpSig.exp;
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sigC = normExpSig.sig;
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}
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sigC = (sigC | 0x0400)<<3;
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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expDiff = expProd - expC;
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if (signProd == signC) {
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/*--------------------------------------------------------------------
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*--------------------------------------------------------------------*/
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if (expDiff <= 0) {
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expZ = expC;
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sigZ = sigC + softfloat_shiftRightJam32(sigProd, 16 - expDiff);
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} else {
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expZ = expProd;
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sig32Z = sigProd + softfloat_shiftRightJam32((uint32_t) sigC<<16, expDiff);
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sigZ = sig32Z>>16 | ((sig32Z & 0xFFFF) != 0);
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}
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if (sigZ < 0x4000) {
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--expZ;
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sigZ <<= 1;
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}
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} else {
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/*--------------------------------------------------------------------
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*--------------------------------------------------------------------*/
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sig32C = (uint32_t) sigC<<16;
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if (expDiff < 0) {
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signZ = signC;
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expZ = expC;
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sig32Z = sig32C - softfloat_shiftRightJam32(sigProd, -expDiff);
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} else if (! expDiff) {
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expZ = expProd;
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sig32Z = sigProd - sig32C;
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if (! sig32Z) goto completeCancellation;
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if (sig32Z & 0x80000000) {
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signZ = ! signZ;
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sig32Z = -sig32Z;
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}
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} else {
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expZ = expProd;
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sig32Z = sigProd - softfloat_shiftRightJam32(sig32C, expDiff);
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}
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shiftDist = softfloat_countLeadingZeros32(sig32Z) - 1;
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expZ -= shiftDist;
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shiftDist -= 16;
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if (shiftDist < 0) {
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sigZ = sig32Z>>(-shiftDist) | ((uint32_t) (sig32Z<<(shiftDist & 31)) != 0);
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} else {
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sigZ = (uint16_t) sig32Z<<shiftDist;
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}
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}
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roundPack:
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return softfloat_roundPackToF16(signZ, expZ, sigZ, status);
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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infProdArg:
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if (magBits) {
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uiZ = packToF16UI(signProd, 0x1F, 0);
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if (signProd == signC || expC != 0x1F) {
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if ((sigA && !expA) || (sigB && !expB) || (sigC && !expC))
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softfloat_raiseFlags(status, softfloat_flag_denormal);
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return uiZ;
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}
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}
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softfloat_raiseFlags(status, softfloat_flag_invalid);
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uiZ = defaultNaNF16UI;
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return softfloat_propagateNaNF16UI(uiZ, uiC, status);
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/*------------------------------------------------------------------------
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*------------------------------------------------------------------------*/
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zeroProd:
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uiZ = packToF16UI(signC, expC, sigC);
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if (!expC && sigC) {
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/* Exact zero plus a denormal */
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softfloat_raiseFlags(status, softfloat_flag_denormal);
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if (softfloat_flushUnderflowToZero(status)) {
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softfloat_raiseFlags(status, softfloat_flag_underflow | softfloat_flag_inexact);
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return packToF16UI(signC, 0, 0);
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}
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}
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if (! (expC | sigC) && (signProd != signC)) {
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completeCancellation:
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uiZ = packToF16UI((softfloat_getRoundingMode(status) == softfloat_round_min), 0, 0);
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}
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return uiZ;
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}
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