twoc.cpp

////////////////////////////////////////////////////////////////////////////////
//
// 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) 2015-2024, 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;
}