/*
 * Copyright (C) 2020-2021 Aloysius Indrayanto
 *
 * This file is part of the eCxx library, see LICENSE file for the license details.
 */

/*
 * ----------------------------------------------------------------------------------
 * The code in this file is copied (with a slight modifications) from:
 *     sqrt32.cpp
 * ----------------------------------------------------------------------------------
 * This file is part of the esp8266 core for Arduino environment.
 *
 * This library is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation; either version 2.1 of the License, or (at your option) any later
 * version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along
 * with this library; if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 * ----------------------------------------------------------------------------------
 */


#include "CoreLib.h"


namespace eCxx {

namespace NodeMCU {


extern uint32_t isqrt32(uint32_t n)
{
    // Based on http://www.codecodex.com/wiki/Calculate_an_integer_square_root#C

    uint32_t c = 0x8000;
    uint32_t g = 0x8000;

    for(;;) {
        if(g * g > n) g ^= c;

        c >>= 1;
        if(!c) return g;

        g |= c;
    }
}


} // namespace NodeMCU

} // namespace eCxx


//
// Function aliases with "C" linkage for compatibility with the Arduino library part
//
extern "C" {

    // make mangle CODE='namespace eCxx { namespace NodeMCU { unsigned int isqrt32(unsigned int) {} } }'
    extern eCxx::uint32_t sqrt32(eCxx::uint32_t n) __ECXX_ATTR_ALIAS("_ZN4eCxx7NodeMCU7isqrt32Ej");

} // extern "C"
