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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/p8_to_ui64.c | |
parent | 657457ef4a08c1f000f272e00f654f4064cc37bd (diff) | |
download | context-6b25a7a970ba9553adf8077ef2eecb50a5d77818.tar.gz |
2023-04-26 23:31:00
Diffstat (limited to 'source/luametatex/source/libraries/softposit/source/p8_to_ui64.c')
-rw-r--r-- | source/luametatex/source/libraries/softposit/source/p8_to_ui64.c | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/source/luametatex/source/libraries/softposit/source/p8_to_ui64.c b/source/luametatex/source/libraries/softposit/source/p8_to_ui64.c new file mode 100644 index 000000000..2a19fe95f --- /dev/null +++ b/source/luametatex/source/libraries/softposit/source/p8_to_ui64.c @@ -0,0 +1,94 @@ + +/*============================================================================ + +This C source file is part of the SoftPosit Posit Arithmetic Package +by S. H. Leong (Cerlane) and John Gustafson. + +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" + +uint_fast64_t p8_to_ui64( posit8_t pA ) { + + union ui8_p8 uA; + uint_fast64_t mask, iZ, tmp; + uint_fast8_t scale = 0, uiA; + bool bitLast, bitNPlusOne; + + uA.p = pA; + uiA = uA.ui; // Copy of the input. + //NaR + //if (uiA==0x80) return 0; + if (uiA>=0x80) return 0; //negative + + if (uiA <= 0x20) { // 0 <= |pA| <= 1/2 rounds to zero. + return 0; + } + else if (uiA < 0x50) { // 1/2 < x < 3/2 rounds to 1. + iZ = 1; + } + else { // Decode the posit, left-justifying as we go. + + uiA -= 0x40; // Strip off first regime bit (which is a 1). + while (0x20 & uiA) { // Increment scale by 1 for each regime sign bit. + scale ++; // Regime sign bit is always 1 in this range. + uiA = (uiA - 0x20) << 1; // Remove the bit; line up the next regime bit. + } + uiA <<= 1; // Skip over termination bit, which is 0. + + iZ = ((uint64_t)uiA | 0x40) << 55; // Left-justify fraction in 32-bit result (one left bit padding) + + mask = 0x2000000000000000 >> scale; // Point to the last bit of the integer part. + + bitLast = (iZ & mask); // Extract the bit, without shifting it. + mask >>= 1; + tmp = (iZ & mask); + bitNPlusOne = tmp; // "True" if nonzero. + iZ ^= tmp; // Erase the bit, if it was set. + tmp = iZ & (mask - 1); // tmp has any remaining bits. // This is bitsMore + iZ ^= tmp; // Erase those bits, if any were set. + + if (bitNPlusOne) { // logic for round to nearest, tie to even + if (bitLast | tmp) iZ += (mask<<1) ; + } + iZ = (uint64_t)iZ >> (61 - scale); // Right-justify the integer. + } + + return iZ; + +} + |