basic_op.c

一份不错的实现ITU-T G729标准的MATLAB源代码！

      carry_int = 0;
     }
   else
     {
      if ((L_var1<0) && (L_var2 <0) && (L_test >0))
        {
         Overflow = 1;
         carry_int = 1;
        }
      else
        {
         if (((L_var1 ^ L_var2) < 0) && (L_test > 0))
           {
            Overflow = 0;
            carry_int = 1;
           }
         else
           {
            Overflow = 0;
            carry_int = 0;
           }
        }
     }

   if (Carry)
     {
      if (L_test == MAX_32)
        {
         Overflow = 1;
         Carry = carry_int;
        }
      else
        {
         if (L_test == (Word32) 0xFFFFFFFFL)
           {
            Carry = 1;
           }
         else
           {
            Carry = carry_int;
           }
        }
     }
   else
     {
      Carry = carry_int;
     }

   return(L_var_out);
  }

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : L_sub_c                                                 |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   Performs 32 bits subtraction of the two 32 bits variables with carry    |
 |   (borrow) : L_var1-L_var2-C. No saturation. Generate carry and Overflow  |
 |   values. The carry and overflow values are binary variables which can    |
 |   be tested and assigned values.                                          |
 |                                                                           |
 |   Complexity weight : 2                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    L_var1   32 bit long signed integer (Word32) whose value falls in the  |
 |             range : 0x8000 0000 <= L_var3 <= 0x7fff ffff.                 |
 |                                                                           |
 |    L_var2   32 bit long signed integer (Word32) whose value falls in the  |
 |             range : 0x8000 0000 <= L_var3 <= 0x7fff ffff.                 |
 |                                                                           |
 |   Outputs :                                                               |
 |                                                                           |
 |    none                                                                   |
 |                                                                           |
 |   Return Value :                                                          |
 |                                                                           |
 |    L_var_out                                                              |
 |             32 bit long signed integer (Word32) whose value falls in the  |
 |             range : 0x8000 0000 <= L_var_out <= 0x7fff ffff.              |
 |                                                                           |
 |   Caution :                                                               |
 |                                                                           |
 |    In some cases the Carry flag has to be cleared or set before using op- |
 |    rators which take into account its value.                              |
 |___________________________________________________________________________|
*/

Word32 L_sub_c(Word32 L_var1, Word32 L_var2)
  {
   Word32 L_var_out;
   Word32 L_test;
   Flag carry_int = 0;

   if (Carry)
     {
      Carry = 0;
      if (L_var2 != MIN_32)
        {
         L_var_out = L_add_c(L_var1,-L_var2);
        }
      else
        {
         L_var_out = L_var1 - L_var2;
         if (L_var1 > 0L)
           {
            Overflow = 1;
            Carry = 0;
           }
        }
     }
   else
     {
      L_var_out = L_var1 - L_var2 - (Word32)0X00000001;
      L_test = L_var1 - L_var2;

      if ((L_test < 0) && (L_var1 > 0) && (L_var2 < 0))
        {
         Overflow = 1;
         carry_int = 0;
        }
      else if ((L_test > 0) && (L_var1 < 0) && (L_var2 > 0))
        {
         Overflow = 1;
         carry_int = 1;
        }
      else if ((L_test > 0) && ((L_var1 ^ L_var2) > 0))
        {
         Overflow = 0;
         carry_int = 1;
        }


      if (L_test == MIN_32)
        {
         Overflow = 1;
         Carry = carry_int;
        }
      else
        {
         Carry = carry_int;
        }
     }

   return(L_var_out);
  }

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : L_negate                                                |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   Negate the 32 bit variable L_var1 with saturation; saturate in the case |
 |   where input is -2147483648 (0x8000 0000).                               |
 |                                                                           |
 |   Complexity weight : 2                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    L_var1   32 bit long signed integer (Word32) whose value falls in the  |
 |             range : 0x8000 0000 <= L_var3 <= 0x7fff ffff.                 |
 |                                                                           |
 |   Outputs :                                                               |
 |                                                                           |
 |    none                                                                   |
 |                                                                           |
 |   Return Value :                                                          |
 |                                                                           |
 |    L_var_out                                                              |
 |             32 bit long signed integer (Word32) whose value falls in the  |
 |             range : 0x8000 0000 <= L_var_out <= 0x7fff ffff.              |
 |___________________________________________________________________________|
*/

Word32 L_negate(Word32 L_var1)
  {
   Word32 L_var_out;

   L_var_out = (L_var1 == MIN_32) ? MAX_32 : -L_var1;
   return(L_var_out);
  }

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : mult_r                                                  |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   Same as mult with rounding, i.e.:                                       |
 |     mult_r(var1,var2) = shr(((var1*var2) + 16384),15) and                 |
 |     mult_r(-32768,-32768) = 32767.                                        |
 |                                                                           |
 |   Complexity weight : 2                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    var1                                                                   |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var1 <= 0x0000 7fff.                   |
 |                                                                           |
 |    var2                                                                   |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var1 <= 0x0000 7fff.                   |
 |                                                                           |
 |   Outputs :                                                               |
 |                                                                           |
 |    none                                                                   |
 |                                                                           |
 |   Return Value :                                                          |
 |                                                                           |
 |    var_out                                                                |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var_out <= 0x0000 7fff.                |
 |___________________________________________________________________________|
*/

Word16 mult_r(Word16 var1, Word16 var2)
  {
   Word16 var_out;
   Word32 L_produit_arr;

   L_produit_arr = (Word32)var1 * (Word32)var2; /* product */
   L_produit_arr += (Word32) 0x00004000;        /* round */
   L_produit_arr &= (Word32) 0xffff8000L;
   L_produit_arr >>= 15;                        /* shift */

   if (L_produit_arr & (Word32) 0x00010000L)   /* sign extend when necessary */
     {
      L_produit_arr |= (Word32) 0xffff0000L;
     }

   var_out = sature(L_produit_arr);
   return(var_out);
  }

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : L_shl