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Diffstat (limited to 'source/luametatex/source/libraries/softposit/source/s_subMagsP32.c')
| -rw-r--r-- | source/luametatex/source/libraries/softposit/source/s_subMagsP32.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/source/luametatex/source/libraries/softposit/source/s_subMagsP32.c b/source/luametatex/source/libraries/softposit/source/s_subMagsP32.c new file mode 100644 index 000000000..4771626de --- /dev/null +++ b/source/luametatex/source/libraries/softposit/source/s_subMagsP32.c @@ -0,0 +1,194 @@ + +/*============================================================================ + +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. + +This C source file was based on SoftFloat IEEE Floating-Point Arithmetic +Package, Release 3d, by John R. Hauser. + +Copyright 2011, 2012, 2013, 2014, 2015, 2016, 2017 The Regents of the +University of California. 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 "platform.h" +#include "internals.h" + +posit32_t softposit_subMagsP32( uint_fast32_t uiA, uint_fast32_t uiB ) { + + uint_fast16_t regA, regB; + uint_fast64_t frac64A=0, frac64B=0; + uint_fast32_t fracA=0, regime, tmp; + bool sign, regSA, regSB, ecarry=0, bitNPlusOne=0, bitsMore=0; + int_fast8_t kA=0; + int_fast32_t expA=0; + int_fast16_t shiftRight; + union ui32_p32 uZ; + + sign = signP32UI( uiA ); + if (sign) + uiA = -uiA & 0xFFFFFFFF; + else + uiB = -uiB & 0xFFFFFFFF; + + if (uiA==uiB){ //essential, if not need special handling + uZ.ui = 0; + return uZ.p; + } + if ((int_fast32_t)uiA < (int_fast32_t)uiB){ + uiA ^= uiB; + uiB ^= uiA; + uiA ^= uiB; + (sign) ? (sign = 0 ) : (sign=1); //A becomes B + } + regSA = signregP32UI( uiA ); + regSB = signregP32UI( uiB ); + + tmp = (uiA<<2)&0xFFFFFFFF; + if (regSA){ + while (tmp>>31){ + kA++; + tmp= (tmp<<1) & 0xFFFFFFFF; + } + } + else{ + kA=-1; + while (!(tmp>>31)){ + kA--; + tmp= (tmp<<1) & 0xFFFFFFFF; + } + tmp&=0x7FFFFFFF; + } + + expA = tmp>>29; //to get 2 bits + frac64A = ((0x40000000ULL | tmp<<1) & 0x7FFFFFFFULL) <<32; + shiftRight = kA; + + + tmp = (uiB<<2) & 0xFFFFFFFF; + if (regSB){ + while (tmp>>31){ + shiftRight--; + tmp= (tmp<<1) & 0xFFFFFFFF; + } + + } + else{ + shiftRight++; + while (!(tmp>>31)){ + shiftRight++; + tmp= (tmp<<1) & 0xFFFFFFFF; + } + tmp&=0x7FFFFFFF; + + } + frac64B = ((0x40000000ULL | tmp<<1) & 0x7FFFFFFFULL) <<32; + + //This is 4kZ + expZ; (where kZ=kA-kB and expZ=expA-expB) + shiftRight = (shiftRight<<2) + expA - (tmp>>29); + if (shiftRight>63){ + uZ.ui = uiA; + if (sign) uZ.ui = -uZ.ui & 0xFFFFFFFF; + return uZ.p; + } + else + (frac64B >>= shiftRight); + + frac64A -= frac64B; + + while((frac64A>>59)==0){ + kA--; + frac64A<<=4; + } + ecarry = (0x4000000000000000 & frac64A);//(0x4000000000000000 & frac64A)>>62; + while (!ecarry){ + if (expA==0){ + kA--; + expA=3; + } + else + expA--; + frac64A<<=1; + ecarry = (0x4000000000000000 & frac64A); + } + + if(kA<0){ + regA = -kA; + regSA = 0; + regime = 0x40000000>>regA; + } + else{ + regA = kA+1; + regSA=1; + regime = 0x7FFFFFFF - (0x7FFFFFFF>>regA); + } + if(regA>30){ + //max or min pos. exp and frac does not matter. + (regSA) ? (uZ.ui= 0x7FFFFFFF): (uZ.ui=0x1); + } + else{ + //remove hidden bits + frac64A = (frac64A & 0x3FFFFFFFFFFFFFFF) >>(regA + 2) ; // 2 bits exp + + fracA = frac64A>>32; + + if (regA<=28){ + bitNPlusOne |= (0x80000000 & frac64A) ; + expA <<= (28-regA); + } + else { + if (regA==30){ + bitNPlusOne = expA&0x2; + bitsMore = (expA&0x1); + expA = 0; + } + else if (regA==29){ + bitNPlusOne = expA&0x1; + expA>>=1; + } + if (fracA>0){ + fracA=0; + bitsMore =1; + } + + } + + uZ.ui = packToP32UI(regime, expA, fracA); + //n+1 frac bit is 1. Need to check if another bit is 1 too if not round to even + if (bitNPlusOne){ + if (0x7FFFFFFF & frac64A)bitsMore=1; + uZ.ui += (uZ.ui&1) | bitsMore; + } + } + if (sign) uZ.ui = -uZ.ui & 0xFFFFFFFF; + return uZ.p; +} + |