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Diffstat (limited to 'source/luametatex/source/libraries/softposit/source/p8_mul.c')
| -rw-r--r-- | source/luametatex/source/libraries/softposit/source/p8_mul.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/source/luametatex/source/libraries/softposit/source/p8_mul.c b/source/luametatex/source/libraries/softposit/source/p8_mul.c new file mode 100644 index 000000000..d565c7a75 --- /dev/null +++ b/source/luametatex/source/libraries/softposit/source/p8_mul.c @@ -0,0 +1,167 @@ + +/*============================================================================ + +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 "platform.h" +#include "internals.h" + +posit8_t p8_mul( posit8_t pA, posit8_t pB ){ + + union ui8_p8 uA, uB, uZ; + uint_fast8_t uiA, uiB; + uint_fast8_t regA, fracA, regime, tmp; + bool signA, signB, signZ, regSA, regSB, bitNPlusOne=0, bitsMore=0, rcarry; + int_fast8_t kA=0; + uint_fast16_t frac16Z; + + uA.p = pA; + uiA = uA.ui; + uB.p = pB; + uiB = uB.ui; + +#ifdef SOFTPOSIT_EXACT + uZ.ui.exact = (uiA.ui.exact & uiB.ui.exact); +#endif + //NaR or Zero + if ( uiA==0x80 || uiB==0x80 ){ + +#ifdef SOFTPOSIT_EXACT + uZ.ui.v = 0x80; + uZ.ui.exact = 0; +#else + uZ.ui = 0x80; +#endif + return uZ.p; + } + else if (uiA==0 || uiB==0){ +#ifdef SOFTPOSIT_EXACT + + uZ.ui.v = 0; + if ( (uiA==0 && uiA.ui.exact) || (uiB==0 && uiB.ui.exact) ) + uZ.ui.exact = 1; + else + uZ.ui.exact = 0; +#else + uZ.ui = 0; +#endif + return uZ.p; + } + + signA = signP8UI( uiA ); + signB = signP8UI( uiB ); + signZ = signA ^ signB; + + if(signA) uiA = (-uiA & 0xFF); + if(signB) uiB = (-uiB & 0xFF); + + regSA = signregP8UI(uiA); + regSB = signregP8UI(uiB); + + tmp = (uiA<<2) & 0xFF; + if (regSA){ + while (tmp>>7){ + kA++; + tmp= (tmp<<1) & 0xFF; + } + } + else{ + kA=-1; + while (!(tmp>>7)){ + kA--; + tmp= (tmp<<1) & 0xFF; + } + tmp&=0x7F; + } + fracA = (0x80 | tmp); + + tmp = (uiB<<2) & 0xFF; + if (regSB){ + while (tmp>>7){ + kA++; + tmp= (tmp<<1) & 0xFF; + } + } + else{ + kA--; + while (!(tmp>>7)){ + kA--; + tmp= (tmp<<1) & 0xFF; + } + tmp&=0x7F; + } + frac16Z = (uint_fast16_t) fracA * (0x80 | tmp); + + rcarry = frac16Z>>15;//1st bit of frac32Z + if (rcarry){ + kA++; + frac16Z>>=1; + } + + if(kA<0){ + regA = (-kA & 0xFF); + regSA = 0; + regime = 0x40>>regA; + } + else{ + regA = kA+1; + regSA=1; + regime = 0x7F-(0x7F>>regA); + } + + + + if(regA>6){ + //max or min pos. exp and frac does not matter. + (regSA) ? (uZ.ui= 0x7F): (uZ.ui=0x1); + } + else{ + //remove carry and rcarry bits and shift to correct position + frac16Z = (frac16Z&0x3FFF) >> regA; + fracA = (uint_fast8_t) (frac16Z>>8); + bitNPlusOne = (0x80 & frac16Z) ; + uZ.ui = packToP8UI(regime, fracA); + + //n+1 frac bit is 1. Need to check if another bit is 1 too if not round to even + if (bitNPlusOne){ + if (0x7F & frac16Z) bitsMore=1; + uZ.ui += (uZ.ui&1) | bitsMore; + } + } + + if (signZ) uZ.ui = -uZ.ui & 0xFF; + return uZ.p; +} + + + |