mp_misc.cpp

来自「含有多种公开密钥算法、多种块加密、多种数据流加密、多种HASH函数、多种Chec」· C++ 代码 · 共 55 行

/*************************************************
* Misc MP Functions Source File                  *
* (C) 1999-2002 The Botan Project                *
*************************************************/

#include <botan/mp_core.h>

extern "C" {

/*************************************************
* Division Core                                  *
*************************************************/
bool bigint_divcore(word q, word y_1, word y_2,
                    word x_1, word x_2, word x_3)
   {
   dword product = (dword)q * y_2;
   y_2 = MP_LOW_WORD(product);

   product = (dword)q * y_1 + MP_HIGH_WORD(product);
   y_1 = MP_LOW_WORD(product);
   word y_0 = MP_HIGH_WORD(product);

   if(y_0 > x_1) return true;
   if(y_0 < x_1) return false;
   if(y_1 > x_2)  return true;
   if(y_1 < x_2)  return false;
   if(y_2 > x_3)  return true;
   if(y_2 < x_3)  return false;
   return false;
   }

/*************************************************
* Compare                                        *
*************************************************/
s32bit bigint_cmp(const word* x, u32bit x_size,
                  const word* y, u32bit y_size)
   {
   if(x_size < y_size) { return (-bigint_cmp(y, y_size, x, x_size)); }

   while(x_size > y_size)
      {
      if(x[x_size-1])
         return 1;
      x_size--;
      }
   for(u32bit j = x_size; j > 0; j--)
      {
      if(x[j-1] > y[j-1]) return 1;
      if(x[j-1] < y[j-1]) return -1;
      }
   return 0;
   }

}