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Diffstat (limited to 'source/luametatex/source/libraries/softposit/source/pX1_to_i32.c')
| -rw-r--r-- | source/luametatex/source/libraries/softposit/source/pX1_to_i32.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/source/luametatex/source/libraries/softposit/source/pX1_to_i32.c b/source/luametatex/source/libraries/softposit/source/pX1_to_i32.c new file mode 100644 index 000000000..58b5b7326 --- /dev/null +++ b/source/luametatex/source/libraries/softposit/source/pX1_to_i32.c @@ -0,0 +1,105 @@ + +/*============================================================================ + +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" + +int_fast32_t pX1_to_i32( posit_1_t pA ) { + + union ui32_pX1 uA; + uint_fast64_t iZ64, mask, tmp; + int_fast32_t iZ, scale = 0, uiA; + bool sign=0, bitLast, bitNPlusOne; + + uA.p = pA; + uiA = uA.ui; // Copy of the input. + //NaR + if (uiA==0x80000000) return 0; + + sign = (uiA > 0x80000000); // sign is True if pA > NaR. + + if (sign) uiA = -uiA & 0xFFFFFFFF; // A is now |A|. + + if (uiA <= 0x30000000) { // 0 <= |pA| <= 1/2 rounds to zero. + return 0; + } + else if (uiA < 0x48000000) { // 1/2 < x < 3/2 rounds to 1. + iZ = 1; + } + else if (uiA <= 0x54000000) { // 3/2 <= x <= 5/2 rounds to 2. + iZ = 2; + } + else if (uiA>0x7FFF9FFF){ //2147418112 + return (sign) ? (-2147483648) : (2147483647); + + } + else { // Decode the posit, left-justifying as we go. + uiA -= 0x40000000; // Strip off first regime bit (which is a 1). + while (0x20000000 & uiA) { // Increment scale by 2 for each regime sign bit. + scale += 2; // Regime sign bit is always 1 in this range. + uiA = (uiA - 0x20000000) << 1; // Remove the bit; line up the next regime bit. + } + + uiA <<= 1; // Skip over termination bit, which is 0. + if (0x20000000 & uiA) scale++; // If exponent is 1, increment the scale. + iZ64 = ((uint64_t)uiA | 0x20000000) << 33; // Left-justify fraction in 64-bit result (one left bit padding) + mask = 0x4000000000000000 >> scale; // Point to the last bit of the integer part. + + bitLast = (iZ64 & mask); // Extract the bit, without shifting it. + mask >>= 1; + tmp = (iZ64 & mask); + bitNPlusOne = tmp; // "True" if nonzero. + iZ64 ^= tmp; // Erase the bit, if it was set. + tmp = iZ64 & (mask - 1); // tmp has any remaining bits. // This is bitsMore + iZ64 ^= tmp; // Erase those bits, if any were set. + + if (bitNPlusOne) { // logic for round to nearest, tie to even + if (bitLast | tmp) iZ64 += (mask << 1); + } + + iZ = (uint64_t)iZ64 >> (62 - scale); // Right-justify the integer. + + } + if (sign) iZ = -iZ; + return iZ; + +} + |