divsi3.c

用于嵌入式Linux系统的标准C的库函数

#define divnorm(num, den, sign) 		\
{						\
  if (num < 0) 					\
    {						\
      num = -num;				\
      sign = 1;					\
    }						\
  else 						\
    {						\
      sign = 0;					\
    }						\
						\
  if (den < 0) 					\
    {						\
      den = - den;				\
      sign = 1 - sign;				\
    } 						\
}





unsigned long 
divmodsi4(int modwanted, unsigned long num, unsigned long den)	
{						
  long int bit = 1;				
  long int res = 0;				
  long prevden;
  while (den < num && bit && !(den & (1L<<31)))			       
    {
      den <<=1;					
      bit <<=1;					
    }						
  while (bit)
    {					
      if (num >= den)
	{				
	  num -= den;				
	  res |= bit;				
	}						
      bit >>=1;					
      den >>=1;					
    }						
  if (modwanted) return num;
  return res;
}


#define exitdiv(sign, res) if (sign) { res = - res;} return res;

long 
__modsi3 (long numerator, long denominator)
{
  int sign = 0;
  long dividend;
  long modul;


  if (numerator < 0) 
    {
      numerator = -numerator;
      sign = 1;
    }
  if (denominator < 0)
    {
      denominator = -denominator;
    }  
  
  modul =  divmodsi4 (1, numerator, denominator);
  if (sign)
    return - modul;
  return modul;
}


long 
__divsi3 (long numerator, long denominator)
{
  int sign;
  long dividend;
  long modul;
  divnorm (numerator, denominator, sign);

  dividend = divmodsi4 (0,  numerator, denominator);
  exitdiv (sign, dividend);
}

long 
__umodsi3 (unsigned long numerator, unsigned long denominator)
{
  long dividend;
  long modul;

modul= divmodsi4 (1,  numerator, denominator);
  return modul;
}

long 
__udivsi3 (unsigned long numerator, unsigned long denominator)
{
  int sign;
  long dividend;
  long modul;
  dividend =   divmodsi4 (0, numerator, denominator);
  return dividend;
}






#ifdef TEST



main ()
{
  long int i, j, k, m;
  for (i = -10000; i < 10000; i += 8)
    {
      for (j = -10000; j < 10000; j += 11)
	{
	  k = i / j;
	  m = __divsi3 (i, j);
	  if (k != m)
	    printf ("fail %d %d %d %d\n", i, j, k, m);
	}
    }
}

#endif