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author | Hans Hagen <pragma@wxs.nl> | 2023-04-27 00:04:07 +0200 |
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committer | Context Git Mirror Bot <phg@phi-gamma.net> | 2023-04-27 00:04:07 +0200 |
commit | 6b25a7a970ba9553adf8077ef2eecb50a5d77818 (patch) | |
tree | f06e40077ba9e55af4bf6cab52313f79f8ea84a8 /source/luametatex/source/libraries/softposit/source/quire8_fdp_sub.c | |
parent | 657457ef4a08c1f000f272e00f654f4064cc37bd (diff) | |
download | context-6b25a7a970ba9553adf8077ef2eecb50a5d77818.tar.gz |
2023-04-26 23:31:00
Diffstat (limited to 'source/luametatex/source/libraries/softposit/source/quire8_fdp_sub.c')
-rw-r--r-- | source/luametatex/source/libraries/softposit/source/quire8_fdp_sub.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/source/luametatex/source/libraries/softposit/source/quire8_fdp_sub.c b/source/luametatex/source/libraries/softposit/source/quire8_fdp_sub.c new file mode 100644 index 000000000..f1de20cb7 --- /dev/null +++ b/source/luametatex/source/libraries/softposit/source/quire8_fdp_sub.c @@ -0,0 +1,136 @@ +/*============================================================================ + +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 <inttypes.h> + +#include "platform.h" +#include "internals.h" + + +//q - (pA*pB) +quire8_t q8_fdp_sub( quire8_t q, posit8_t pA, posit8_t pB ){ + + union ui8_p8 uA, uB; + union ui32_q8 uqZ, uqZ1, uqZ2; + uint_fast8_t uiA, uiB; + uint_fast8_t fracA, tmp; + bool signA, signB, signZ2, regSA, regSB, rcarry; + int_fast8_t kA=0, shiftRight=0; + uint_fast32_t frac32Z; + + uqZ1.q = q; + + uA.p = pA; + uiA = uA.ui; + uB.p = pB; + uiB = uB.ui; + + //NaR + if (isNaRQ8(q) || isNaRP8UI(uA.ui) || isNaRP8UI(uB.ui)){ + uqZ2.ui=0x80000000; + return uqZ2.q; + } + else if (uiA==0 || uiB==0) + return q; + + + //max pos (sign plus and minus) + signA = signP8UI( uiA ); + signB = signP8UI( uiB ); + signZ2 = 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; + } + frac32Z = (uint_fast32_t)( fracA * (0x80 | tmp) ) <<16; + + rcarry = frac32Z>>31;//1st bit (position 2) of frac32Z, hidden bit is 4th bit (position 3) + if (rcarry){ + kA ++; + frac32Z>>=1; + } + + //default dot is between bit 19 and 20, extreme left bit is bit 0. Last right bit is bit 31. + //Scale = 2^es * k + e => 2k + e // firstPost = 19-kA, shift = firstPos -1 (because frac32Z start from 2nd bit) + //int firstPos = 19 - kA; + shiftRight = 18-kA; + + uqZ2.ui = frac32Z>> shiftRight; + + //This is the only difference from ADD (signZ2) and (!signZ2) + if (!signZ2) uqZ2.ui = -uqZ2.ui & 0xFFFFFFFF; + + //Addition + uqZ.ui = uqZ2.ui + uqZ1.ui; + + //Exception handling + if (isNaRQ8(uqZ.q) ) uqZ.q.v=0; + + return uqZ.q; +} |