log2_approx.c 1.69 KB
/*
 * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The OpenAirInterface Software Alliance licenses this file to You under
 * the OAI Public License, Version 1.0  (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.openairinterface.org/?page_id=698
 *
 * 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.
 *-------------------------------------------------------------------------------
 * For more information about the OpenAirInterface (OAI) Software Alliance:
 *      contact@openairinterface.org
 */

unsigned char log2_approx(unsigned int x)
{

  int i;
  unsigned char l2;

  l2=0;

  for (i=0; i<31; i++)
    if ((x&(1<<i)) != 0)
      l2 = i+1;

  //l2 = i;

  //  printf("log2_approx = %d\n",l2);
  return(l2);
}

unsigned char factor2(unsigned int x)
{

  int i;
  unsigned char l2;

  l2=0;

  for (i=0; i<31; i++)
    if ((x&(1<<i)) != 0)
      break;

  l2 = i;

  //printf("factor2(%d) = %d\n",x,l2);
  return(l2);
}



unsigned char log2_approx64(unsigned long long int x)
{

  int i;
  unsigned char l2;

  l2=0;

  for (i=0; i<63; i++)
    if ((x&(((long long int) 1)<<i)) != 0)
      //     l2 = i+1;
      l2 = i;

  //  printf("log2_approx = %d\n",l2);
  return(l2);
}