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Diffstat (limited to 'source/luametatex/source/libraries/softposit/source/c_convertQuire16ToPosit16.c')
| -rw-r--r-- | source/luametatex/source/libraries/softposit/source/c_convertQuire16ToPosit16.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/source/luametatex/source/libraries/softposit/source/c_convertQuire16ToPosit16.c b/source/luametatex/source/libraries/softposit/source/c_convertQuire16ToPosit16.c new file mode 100644 index 000000000..80deccc4c --- /dev/null +++ b/source/luametatex/source/libraries/softposit/source/c_convertQuire16ToPosit16.c @@ -0,0 +1,159 @@ + +/*============================================================================ + +This C source file is part of the SoftPosit Posit Arithmetic Package +by S. H. Leong (Cerlane). + +Copyright 2017, 2018 A*STAR. All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + + 1. Redistributions of source code must retain the above copyright notice, + this list of conditions, and the following disclaimer. + + 2. Redistributions in binary form must reproduce the above copyright notice, + this list of conditions, and the following disclaimer in the documentation + and/or other materials provided with the distribution. + + 3. Neither the name of the University nor the names of its contributors may + be used to endorse or promote products derived from this software without + specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY +EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE +DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY +DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES +(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +=============================================================================*/ + +#include <math.h> + +#include "platform.h" +#include "internals.h" + +//TODO DEPRECATED +posit16_t convertQ16ToP16(quire16_t qA){ + return q16_to_p16(qA); +} + + +posit16_t q16_to_p16(quire16_t qA){ + union ui128_q16 uZ; + union ui16_p16 uA; + uint_fast16_t regA, fracA = 0, shift=0, regime; + uint_fast64_t frac64A; + bool sign, regSA=0, bitNPlusOne=0, bitsMore=0; + int_fast8_t expA = 0; + + + if (isQ16Zero(qA)){ + uA.ui=0; + return uA.p; + } + //handle NaR + else if (isNaRQ16(qA)){ + uA.ui=0x8000; + return uA.p; + } + + uZ.q = qA; + + sign = uZ.ui[0]>>63; + + if(sign){ + //probably need to do two's complement here before the rest. + if (uZ.ui[1]==0){ + uZ.ui[0] = -uZ.ui[0]; + } + else{ + uZ.ui[1] = -uZ.ui[1]; + uZ.ui[0] = ~(uZ.ui[0]); + } + } + + + int noLZ =0; + + if (uZ.ui[0] == 0){ + noLZ+=64; + uint_fast64_t tmp = uZ.ui[1]; + + while(!(tmp>>63)){ + noLZ++; + tmp<<=1; + } + frac64A = tmp; + } + else{ + uint_fast64_t tmp = uZ.ui[0]; + int noLZtmp = 0; + + while(!(tmp>>63)){ + noLZtmp++; + tmp<<=1; + } + noLZ+=noLZtmp; + frac64A = tmp; + frac64A+= ( uZ.ui[1]>>(64-noLZtmp) ); + if (uZ.ui[1]<<noLZtmp)bitsMore = 1; + } + + //default dot is between bit 71 and 72, extreme left bit is bit 0. Last right bit is bit 127. + //Equations derived from quire16_mult last_pos = 71 - (kA<<1) - expA and first_pos = last_pos - frac_len + int kA=(71-noLZ) >> 1; + expA = 71 - noLZ - (kA<<1) ; + + if(kA<0){ + regA = (-kA & 0xFFFF); + regSA = 0; + regime = 0x4000>>regA; + } + else{ + regA = kA+1; + regSA=1; + regime = 0x7FFF - (0x7FFF>>regA); + } + + if(regA>14){ + //max or min pos. exp and frac does not matter. + (regSA) ? (uA.ui= 0x7FFF): (uA.ui=0x1); + } + else{ + + //remove hidden bit + frac64A&=0x7FFFFFFFFFFFFFFF; + shift = regA+50; //1 es bit, 1 sign bit and 1 r terminating bit , 16+31+3 + fracA = frac64A>>shift; + + if (regA!=14){ + bitNPlusOne = (frac64A>>(shift-1)) & 0x1; + unsigned long long tmp = frac64A<<(65-shift); + if(frac64A<<(65-shift)) bitsMore = 1; + } + else if (frac64A>0){ + fracA=0; + bitsMore=1; + } + + if (regA==14 && expA) bitNPlusOne = 1; + + uA.ui = packToP16UI(regime, regA, expA, fracA); + + if (bitNPlusOne){ + uA.ui += (uA.ui&1) | bitsMore; + } + } + + if (sign) uA.ui = -uA.ui & 0xFFFF; + return uA.p; +} + + + |