/*
 * Copyright (C) 2018 David Robillard <d@drobilla.net>
 *
 * This program is free software; 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 2 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
 * MERCHANTABILITY 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; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef _OPERATIONS_HPP_
#define _OPERATIONS_HPP_

#include <cassert>
#include <climits>
#include <cstddef>
#include <type_traits>

/// IntegralIndex<T> only exists if T is integral
template <typename T>
using IntegralIndex = std::enable_if_t<std::is_integral<T>::value, int>;

/// BitsetIndex<T> only exists if T is not integral (must be a bitset)
template <typename T>
using BitsetIndex = std::enable_if_t<!std::is_integral<T>::value, int>;

/// Return the `index`th bit in `field`
template <typename T>
bool
testBit(const T& field, const IntegralIndex<T> index)
{
	assert(size_t(index) < sizeof(field) * CHAR_BIT);
	return field & (((T)1) << index);
}

/// Return the `index`th bit in `field`
template <typename T>
bool
testBit(const T& field, const BitsetIndex<T> index)
{
	return field.test(index);
}

/// Set the `index`th bit in `field` to `value`
template <typename T>
void
setBit(T& field, const IntegralIndex<T> index, const bool value)
{
	assert(size_t(index) < sizeof(field) * CHAR_BIT);
	field ^= (-value ^ field) & ((T)1 << index);
	assert(testBit(field, index) == value);
}

/// Set the `index`th bit in `field` to `value`
template <typename T>
void
setBit(T& field, const BitsetIndex<T> index, const bool value)
{
	field.set(index, value);
}

#endif