mirror of https://github.com/ARMmbed/mbed-os.git
52 lines
1.3 KiB
C
52 lines
1.3 KiB
C
/*
|
|
* Copyright (c) 2014-2018, Arm Limited and affiliates.
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
#include "nsconfig.h"
|
|
#include "ns_types.h"
|
|
#include "isqrt.h"
|
|
|
|
/**
|
|
* \brief Calculates integer square root
|
|
*
|
|
* Algorithm is from http://www.codecodex.com/wiki/Calculate_an_integer_square_root
|
|
*
|
|
* \param n number
|
|
*
|
|
* \return square root of the number (rounded down)
|
|
*/
|
|
|
|
uint32_t isqrt32(uint32_t n)
|
|
{
|
|
uint32_t root, remainder, place;
|
|
|
|
root = 0;
|
|
remainder = n;
|
|
place = 0x40000000;
|
|
|
|
while (place > remainder) {
|
|
place = place >> 2;
|
|
}
|
|
while (place) {
|
|
if (remainder >= root + place) {
|
|
remainder = remainder - root - place;
|
|
root = root + (place << 1);
|
|
}
|
|
root = root >> 1;
|
|
place = place >> 2;
|
|
}
|
|
return root;
|
|
}
|