Subversion Repositories zipcpu

////////////////////////////////////////////////////////////////////////////////

//

// Filename:    twoc.cpp

//

// Project:     Zip CPU -- a small, lightweight, RISC CPU soft core

//

// 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) 2015,2017, 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;

}