// quantum computing emulation library
//
// R. Perry, January 2022
//
#include <iostream>
#include <cstdlib> // rand(), srand(), RAND_MAX, atoi(), getenv(), malloc(), exit()
#include <ctime>   // time()

#include "lib.h"

namespace qce
{
// non-template functions:

// set srand() using time(0) or SRAND environment variable
unsigned int SRAND() {
  char *env = getenv( "SRAND"); unsigned int seed = 0; if( env) seed = atoi(env);
  if( seed == 0) seed = time(0);
  srand( seed); return seed;
}
// 0.0 <= drand < 1.0
double drand() {
  return rand()/(RAND_MAX+1.0);
}
// 0 <= irand < n
unsigned long irand( unsigned long n) {
  return n*drand();
}
// print binary, n bits
void printb( unsigned long x, unsigned int n) {
  unsigned long mask = 1LU << (n-1);
  while( mask) { std::cout << ((x & mask) ? '1' : '0'); mask >>= 1; }
}
// bit reverse, used by qfft()
unsigned long bitrev( unsigned long x, unsigned int nbits) {
  unsigned long r = 0;
  for( unsigned int i = 0; i < nbits; ++i) { r <<= 1; r |= x & 1; x >>= 1; }
  return r;
}
// print error message and exit
void error( const char *msg) {
  std::cerr << msg << std::endl; exit(1);
}
// malloc with exit on error
void *emalloc( unsigned long size) {
  void *r = malloc(size); if( !r) { error( "qce: malloc() failed"); }  return r;
}

} // namespace qce