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Diffstat (limited to 'source/luametatex/source/libraries/softposit/source/p16_to_p8.c')
| -rw-r--r-- | source/luametatex/source/libraries/softposit/source/p16_to_p8.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/source/luametatex/source/libraries/softposit/source/p16_to_p8.c b/source/luametatex/source/libraries/softposit/source/p16_to_p8.c new file mode 100644 index 000000000..74c198b99 --- /dev/null +++ b/source/luametatex/source/libraries/softposit/source/p16_to_p8.c @@ -0,0 +1,120 @@ +/*============================================================================ + +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" + +posit8_t p16_to_p8( posit16_t pA ) { + + union ui16_p16 uA; + union ui8_p8 uZ; + uint_fast16_t uiA, tmp, regime; + uint_fast16_t exp_frac16A=0; + bool sign, regSA, bitsMore=0; + int_fast8_t kA=0, regA; + + uA.p = pA; + uiA = uA.ui; + + if (uiA==0x8000 || uiA==0 ){ + uZ.ui = (uiA>>8) &0xFF; + return uZ.p; + } + + sign = signP16UI( uiA ); + + if (sign) uiA = -uiA & 0xFFFF; + regSA = signregP16UI(uiA); + + tmp = (uiA<<2) & 0xFFFF; + if (regSA){ + while (tmp>>15){ + kA++; + tmp= (tmp<<1) & 0xFFFF; + } + } + else{ + kA=-1; + while (!(tmp>>15)){ + kA--; + tmp= (tmp<<1) & 0xFFFF; + } + tmp&=0x7FFF; + } + + if (kA<-3 || kA>=3){ + (kA<0) ? (uZ.ui=0x1):(uZ.ui= 0x7F); + } + else{ + //2nd bit exp + exp_frac16A = tmp; + if(kA<0){ + regA = ((-kA)<<1) - (exp_frac16A>>14); + if (regA==0) regA=1; + regSA = 0; + regime = 0x40>>regA; + } + else{ + + (kA==0)?(regA=1 + (exp_frac16A>>14)): (regA = ((kA+1)<<1) + (exp_frac16A>>14) -1); + regSA=1; + regime = 0x7F - (0x7F>>regA); + } + if (regA>5){ + uZ.ui = regime; + } + else{ + //int shift = regA+8; + //exp_frac16A= ((exp_frac16A)&0x3FFF) >> shift; //first 2 bits already empty (for sign and regime terminating bit) + uZ.ui = regime + ( ((exp_frac16A)&0x3FFF)>>(regA+8) ); + + } + + } + + if ( exp_frac16A & (0x80<<regA) ){ + bitsMore = exp_frac16A & (0xFFFF>>(9-regA)); + uZ.ui += (uZ.ui&1) | bitsMore; + + } + if (sign) uZ.ui = -uZ.ui & 0xFF; + + return uZ.p; +} + |