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[/] [zipcpu/] [trunk/] [bench/] [cpp/] [twoc.cpp] - Rev 165
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//////////////////////////////////////////////////////////////////////////// // // Filename: twoc.cpp // // Project: A Doubletime Pipelined FFT // // Purpose: Some various two's complement related C++ helper routines. // Specifically, these help extract signed numbers from // packed bitfields, while guaranteeing that the upper bits // are properly sign extended (or not) as desired. // // Creator: Dan Gisselquist, Ph.D. // Gisselquist Technology, LLC // /////////////////////////////////////////////////////////////////////////// // // Copyright (C) 2015, Gisselquist Technology, LLC // // This program is free software (firmware): you can redistribute it and/or // modify it under the terms of the GNU General Public License as published // by the Free Software Foundation, either version 3 of the License, or (at // your option) any later version. // // This program is distributed in the hope that it will be useful, but WITHOUT // ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License // for more details. // // You should have received a copy of the GNU General Public License along // with this program. (It's in the $(ROOT)/doc directory, run make with no // target there if the PDF file isn't present.) If not, see // <http://www.gnu.org/licenses/> for a copy. // // License: GPL, v3, as defined and found on www.gnu.org, // http://www.gnu.org/licenses/gpl.html // // /////////////////////////////////////////////////////////////////////////// #include "twoc.h" long sbits(const long val, const int bits) { long r; r = val & ((1l<<bits)-1); if (r & (1l << (bits-1))) r |= (-1l << bits); return r; } unsigned long ubits(const long val, const int bits) { unsigned long r = val & ((1l<<bits)-1); return r; }
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