prototype.c

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    else if (var2 >= 15)
      var_out = (var1 < 0) ? -1 : 0;
    else if (var1 < 0)
      var_out = ~((~var1) >> var2);
    else
      var_out = var1 >> var2;

    return (var_out);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : mult                                                    |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |    Performs the multiplication of var1 by var2 and gives a 16 bit result  |
 |    which is scaled i.e.:                                                  |
 |             mult(var1,var2) = extract_l(L_shr((var1 times var2),15)) and  |
 |             mult(-32768,-32768) = 32767.                                  |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |
 |   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 (Word16 var1, Word16 var2)
{
    Word16 var_out;
    Word32 L_product;

    L_product = (Word32) var1 *(Word32) var2;

    L_product = (L_product & (Word32) 0xffff8000L) >> 15;

    if (L_product & (Word32) 0x00010000L)
        L_product = L_product | (Word32) 0xffff0000L;

    var_out = saturate (L_product);
    return (var_out);
}

Word16 mult_nomac (Word16 var1, Word16 var2)
{
    return mult(var1, var2);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : L_mult                                                  |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   L_mult is the 32 bit result of the multiplication of var1 times var2    |
 |   with one shift left i.e.:                                               |
 |        L_mult(var1,var2) = L_shl((var1 times var2),1) and                 |
 |        L_mult(-32768,-32768) = 2147483647.                                |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |
 |   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 :                                                          |
 |                                                                           |
 |    L_var_out                                                              |
 |             32 bit long signed integer (Word32) whose value falls in the  |
 |             range : 0x8000 0000 <= L_var_out <= 0x7fff ffff.              |
 |___________________________________________________________________________|
*/

Word32 L_mult (Word16 var1, Word16 var2)
{
    Word32 L_var_out;

    L_var_out = (Word32) var1 *(Word32) var2;

    if (L_var_out != (Word32) 0x40000000L)
      L_var_out *= 2;
    else
    {
        Overflow = 1;
        L_var_out = MAX_32;
    }

    return (L_var_out);
}

Word32 L_mult_nomac (Word16 var1, Word16 var2)
{
	return L_mult(var1, var2);
}


/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : negate                                                  |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   Negate var1 with saturation, saturate in the case where input is -32768:|
 |                negate(var1) = sub(0,var1).                                |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    var1                                                                   |
 |             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 negate (Word16 var1)
{
    Word16 var_out;

    var_out = (var1 == MIN_16) ? MAX_16 : -var1;
    return (var_out);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : extract_h                                               |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   Return the 16 MSB of L_var1.                                            |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    L_var1                                                                 |
 |             32 bit long signed integer (Word32 ) whose value falls in the |
 |             range : 0x8000 0000 <= L_var1 <= 0x7fff ffff.                 |
 |                                                                           |
 |   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 extract_h (Word32 L_var1)
{
    Word16 var_out;

    var_out = (Word16) (L_var1 >> 16);
    return (var_out);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : extract_l                                               |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   Return the 16 LSB of L_var1.                                            |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    L_var1                                                                 |
 |             32 bit long signed integer (Word32 ) whose value falls in the |
 |             range : 0x8000 0000 <= L_var1 <= 0x7fff ffff.                 |
 |                                                                           |
 |   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 extract_l (Word32 L_var1)
{
    Word16 var_out;

    var_out = (Word16) L_var1;
    return (var_out);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : round                                                   |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   Round the lower 16 bits of the 32 bit input number into the MS 16 bits  |
 |   with saturation. Shift the resulting bits right by 16 and return the 16 |
 |   bit number:                                                             |
 |               round(L_var1) = extract_h(L_add(L_var1,32768))              |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    L_var1                                                                 |
 |             32 bit long signed integer (Word32 ) whose value falls in the |
 |             range : 0x8000 0000 <= L_var1 <= 0x7fff ffff.                 |
 |                                                                           |
 |   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 round (Word32 L_var1)
{
    Word16 var_out;
    Word32 L_rounded;

    L_rounded = L_add (L_var1, (Word32) 0x00008000L);
    var_out = extract_h (L_rounded);
    return (var_out);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : L_mac                                                   |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |   Multiply var1 by var2 and shift the result left by 1. Add the 32 bit    |
 |   result to L_var3 with saturation, return a 32 bit result:               |
 |        L_mac(L_var3,var1,var2) = L_add(L_var3,L_mult(var1,var2)).         |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |