int.c

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/*
This file is part of BitPunch
Copyright (C) 2013-2015 Frantisek Uhrecky <frantisek.uhrecky[what here]gmail.com>
Copyright (C) 2013-2014 Andrej Gulyas <andrej.guly[what here]gmail.com>
Copyright (C) 2013-2014 Marek Klein  <kleinmrk[what here]gmail.com>
Copyright (C) 2013-2014 Filip Machovec  <filipmachovec[what here]yahoo.com>
Copyright (C) 2013-2014 Jozef Kudlac <jozef[what here]kudlac.sk>

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 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
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, see <http://www.gnu.org/licenses/>.
*/
#include "int.h"
 
int BPU_isPrime(int n) {
  int i;
  if (n == 2)
    return 1;
  for (i = 2; i <= n/2.0; i++) {   //TODO: import math.h and use sqrt(n)
    if (n % i == 0)
      return 0;
  }
  return 1;
}

int msb32(uint32_t x, int start, int len, int ele_size) {
  // crop lenght to half
  len /= 2;

  // last recursion
  if (len == 1) {
    // return position of highest bit
    if ((x >> len) == 1ul)
      return start+1;
    else
      return start;
  }
  
  // right half of integer
  if ((x >> len) != 0ul) {
    start += len;
    x >>= len;
  }
  // left half of integer
  else {
    x <<= ele_size - len;
    x >>= ele_size - len;
  }

  // recursion
  return msb32(x, start, len, ele_size);
}