mathevrc.c

EVRC是用于高通公司的语音编码

 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var1 <= 0x7fff ffff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     swOut
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range
 *                     0xffff 8000 <= swOut <= 0x0000 7fff.
 *
 *   IMPLEMENTATION:
 *
 *   KEYWORDS: assign, truncate
 *
 *************************************************************************/

Shortword extract_h(Longword L_var1)
{
	Shortword var2;

    OP_COUNT(1);        /* Complexity Count -- LT 6/96 */

	var2 = (Shortword) (0x0000ffffL & (L_var1 >> 16));
	return (var2);
}

/***************************************************************************
 *
 *   FUNCTION NAME: extract_l
 *
 *   PURPOSE:
 *
 *     Extract the 16 LS bits of a 32 bit Longword.  Return the 16 bit
 *     number as a Shortword.  The upper portion of the input Longword
 *     has no impact whatsoever on the output.
 *
 *   INPUTS:
 *
 *     L_var1
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var1 <= 0x7fff ffff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     swOut
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range
 *                     0xffff 8000 <= swOut <= 0x0000 7fff.
 *
 *
 *   KEYWORDS: extract, assign
 *
 *************************************************************************/

Shortword extract_l(Longword L_var1)
{
	Shortword var2;

    OP_COUNT(1);        /* Complexity Count -- LT 6/96 */

	var2 = (Shortword) (0x0000ffffL & L_var1);
	return (var2);
}

/****************************************************************************
 *
 *     FUNCTION NAME: isOverflow
 *
 *     PURPOSE:
 *
 *        Check to see whether an overflow/saturation/limiting has occurred 
 *
 *     INPUTS:
 *
 *       none
 *
 *
 *     OUTPUTS:             none
 *
 *     RETURN VALUE:        1 if overflow has been flagged
 *                          0 otherwise
 *
 *     KEYWORDS: saturation, limit, overflow
 *
 ***************************************************************************/

int isOverflow(void)
{

	return (giOverflow);
}

/***************************************************************************
 *
 *   FUNCTION NAME: L_abs
 *
 *   PURPOSE:
 *
 *     Take the absolute value of the 32 bit input.  An input of
 *     -0x8000 0000 results in a return value of 0x7fff ffff.
 *
 *   INPUTS:
 *
 *     L_var1
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var1 <= 0x7fff ffff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     L_Out
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var1 <= 0x7fff ffff.
 *
 *
 *
 *   KEYWORDS: absolute value, abs
 *
 *************************************************************************/
Longword L_abs(Longword L_var1)
{
	Longword L_Out;

    OP_COUNT(3);        /* Complexity Count -- LT 6/96 */

    if (L_var1 == LW_MIN)
	{
		L_Out = LW_MAX;
		giOverflow = 1;
	}
	else
	{
		if (L_var1 < 0)
			L_Out = -L_var1;
		else
			L_Out = L_var1;
	}
	return (L_Out);
}

/***************************************************************************
 *
 *   FUNCTION NAME: L_add
 *
 *   PURPOSE:
 *
 *     Perform the addition of the two 32 bit input variables with
 *     saturation.
 *
 *   INPUTS:
 *
 *     L_var1
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var1 <= 0x7fff ffff.
 *     L_var2
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var2 <= 0x7fff ffff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     L_Out
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var1 <= 0x7fff ffff.
 *
 *   IMPLEMENTATION:
 *
 *     Perform the addition of the two 32 bit input variables with
 *     saturation.
 *
 *     L_Out = L_var1 + L_var2
 *
 *     L_Out is set to 0x7fff ffff if the operation results in an
 *     overflow.  L_Out is set to 0x8000 0000 if the operation
 *     results in an underflow.
 *
 *   KEYWORDS: add, addition
 *
 *************************************************************************/
Longword L_add(Longword L_var1, Longword L_var2)
{
	Longword L_Sum;
	double dSum;

    OP_COUNT(2);        /* Complexity Count -- LT 6/96 */

    dSum = (double) L_var1 + (double) L_var2;
	L_Sum = L_var1 + L_var2;

	if (dSum != (double) L_Sum)
	{
		/* overflow occurred */
        L_Sum = L_saturate(dSum);   OP_COUNT(-4);
	}

	return (L_Sum);
}

/***************************************************************************
 *
 *   FUNCTION NAME: L_deposit_h
 *
 *   PURPOSE:
 *
 *     Put the 16 bit input into the 16 MSB's of the output Longword.  The
 *     LS 16 bits are zeroed.
 *
 *   INPUTS:
 *
 *     var1
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range 0xffff 8000 <= var1 <= 0x0000 7fff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     L_Out
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var1 <= 0x7fff 0000.
 *
 *
 *   KEYWORDS: deposit, assign, fractional assign
 *
 *************************************************************************/

Longword L_deposit_h(Shortword var1)
{
	Longword L_var2;

    OP_COUNT(1);        /* Complexity Count -- LT 6/96 */

    L_var2 = (Longword) var1 << 16;
	return (L_var2);
}

/***************************************************************************
 *
 *   FUNCTION NAME: L_deposit_l
 *
 *   PURPOSE:
 *
 *     Put the 16 bit input into the 16 LSB's of the output Longword with
 *     sign extension i.e. the top 16 bits are set to either 0 or 0xffff.
 *
 *   INPUTS:
 *
 *     var1
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range 0xffff 8000 <= var1 <= 0x0000 7fff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     L_Out
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0xffff 8000 <= L_var1 <= 0x0000 7fff.
 *
 *   KEYWORDS: deposit, assign
 *
 *************************************************************************/

Longword L_deposit_l(Shortword var1)
{
	Longword L_Out;

    OP_COUNT(1);        /* Complexity Count -- LT 6/96 */

    L_Out = var1;
	return (L_Out);
}

/***************************************************************************
 *
 *   FUNCTION NAME: L_mac
 *
 *   PURPOSE:
 *
 *     Multiply accumulate.  Fractionally multiply two 16 bit
 *     numbers together with saturation.  Add that result to the
 *     32 bit input with saturation.  Return the 32 bit result.
 *
 *   INPUTS:
 *
 *     var1
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range 0xffff 8000 <= var1 <= 0x0000 7fff.
 *     var2
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range 0xffff 8000 <= var2 <= 0x0000 7fff.
 *     L_var3
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var2 <= 0x7fff ffff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     L_Out
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var1 <= 0x7fff ffff.
 *
 *   IMPLEMENTATION:
 *
 *     Fractionally multiply two 16 bit numbers together with
 *     saturation.  The only numbers which will cause saturation on
 *     the multiply are 0x8000 * 0x8000.
 *
 *     Add that result to the 32 bit input with saturation.
 *     Return the 32 bit result.
 *
 *     Please note that this is not a true multiply accumulate as
 *     most processors would implement it.  The 0x8000*0x8000
 *     causes and overflow for this instruction.  On most
 *     processors this would cause an overflow only if the 32 bit
 *     input added to it were positive or zero.
 *
 *   KEYWORDS: mac, multiply accumulate
 *
 *************************************************************************/

Longword L_mac(Longword L_var3, Shortword var1, Shortword var2)
{
	Longword L_product;
	double dlwA, dlwB;

    OP_COUNT(1);        /* Complexity Count -- LT 6/96 */

    L_product = (Longword) var1 *var2;  /* integer multiply */
	if (L_product == (Longword) 0x40000000)
	{
		/* the event 0x8000 * 0x8000, the only possible saturation 
		 * in the multiply */
        L_product = L_saturate(2147483648.0 + (double) L_var3); OP_COUNT(-4);
	}
	else
	{
		/* no overflow possible in mult */
		L_product = L_product << 1;
        L_product = L_add(L_var3, L_product);   OP_COUNT(-2);
	}
	return (L_product);
}

/***************************************************************************
 *
 *   FUNCTION NAME: L_msu
 *
 *   PURPOSE:
 *
 *     Multiply and subtract.  Fractionally multiply two 16 bit
 *     numbers together with saturation.  Subtract that result from
 *     the 32 bit input with saturation.  Return the 32 bit result.
 *
 *   INPUTS:
 *
 *     var1
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range 0xffff 8000 <= var1 <= 0x0000 7fff.
 *     var2
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range 0xffff 8000 <= var2 <= 0x0000 7fff.
 *     L_var3
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var2 <= 0x7fff ffff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     L_Out
 *                     32 bit long signed integer (Longword) whose value
 *                     falls in the range
 *                     0x8000 0000 <= L_var1 <= 0x7fff ffff.
 *
 *   IMPLEMENTATION:
 *
 *     Fractionally multiply two 16 bit numbers together with
 *     saturation.  The only numbers which will cause saturation on
 *     the multiply are 0x8000 * 0x8000.
 *
 *     Subtract that result from the 32 bit input with saturation.
 *     Return the 32 bit result.
 *
 *     Please note that this is not a true multiply accumulate as
 *     most processors would implement it.  The 0x8000*0x8000
 *     causes and overflow for this instruction.  On most
 *     processors this would cause an overflow only if the 32 bit
 *     input added to it were negative or zero.
 *
 *   KEYWORDS: mac, multiply accumulate, msu
 *
 *************************************************************************/

Longword L_msu(Longword L_var3, Shortword var1, Shortword var2)
{
	Longword L_product;
	double dlwA, dlwB;

    OP_COUNT(1);        /* Complexity Count -- LT 6/96 */

    L_product = (Longword) var1 *var2;  /* integer multiply */
	if (L_product == (Longword) 0x40000000)
	{
		/* the event 0x8000 * 0x8000, the only possible saturation 
		 * in the multiply */
        L_product = L_saturate((double) L_var3 - 2147483648.0); OP_COUNT(-4);
	}
	else
	{
		/* no overflow possible in mult */
		L_product <<= 1;
        L_product = L_sub(L_var3, L_product);   OP_COUNT(-2); /* LT 6/96 */
	}
	return (L_product);
}

/***************************************************************************
 *
 *   FUNCTION NAME: L_mult
 *
 *   PURPOSE:
 *