mathevrc.c

EVRC是用于高通公司的语音编码

/**********************************************************************
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To the extent to which the Source(s) may legally and freely do so, the 
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perform, display and distribute the Contribution and derivative works 
thereof consistent with 3GPP2's and each Organizational Partner's 
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and procedures and (ii) copyright and sell, if applicable) in 3GPP2's name 
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even though this Publication may contain the Contribution or a derivative 
work thereof.  The Contribution shall disclose any known limitations on 
the Source's rights to license as herein provided.

When a Contribution is submitted by the Source(s) to assist the 
formulating groups of 3GPP2 or any of its Organizational Partners, it 
is proposed to the Committee as a basis for discussion and is not to 
be construed as a binding proposal on the Source(s).  The Source(s) 
specifically reserve(s) the right to amend or modify the material 
contained in the Contribution. Nothing contained in the Contribution 
shall, except as herein expressly provided, be construed as conferring 
by implication, estoppel or otherwise, any license or right under (i) 
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With respect to the Software necessary for the practice of any or 
all Normative portions of the Enhanced Variable Rate Codec (EVRC) as 
it exists on the date of submittal of this form, should the EVRC be 
approved as a Specification or Report by 3GPP2, or as a transposed 
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*******************************************************************/
 
/*======================================================================*/
/*     Enhanced Variable Rate Codec - Bit-Exact C Specification         */
/*     Copyright (C) 1997-1998 Telecommunications Industry Association. */
/*     All rights reserved.                                             */
/*----------------------------------------------------------------------*/
/* Note:  Reproduction and use of this software for the design and      */
/*     development of North American Wideband CDMA Digital              */
/*     Cellular Telephony Standards is authorized by the TIA.           */
/*     The TIA does not authorize the use of this software for any      */
/*     other purpose.                                                   */
/*                                                                      */
/*     The availability of this software does not provide any license   */
/*     by implication, estoppel, or otherwise under any patent rights   */
/*     of TIA member companies or others covering any use of the        */
/*     contents herein.                                                 */
/*                                                                      */
/*     Any copies of this software or derivative works must include     */
/*     this and all other proprietary notices.                          */
/*======================================================================*/
/***************************************************************************
 *
 *   File Name:  mathevrc.c
 *
 *   Purpose:  Contains functions which implement the primitive
 *     arithmetic operations.
 *
 *      The functions in this file are listed below.  Some of them are
 *      defined in terms of other basic operations.  One of the
 *      routines, saturate() is static.  This is not a basic
 *      operation, and is not referenced outside the scope of this
 *      file.
 *
 *
 *       abs_s()
 *       add()
 *       clearOverflow()
 *       divide_s()
 *       extract_h()
 *       extract_l()
 *       isOverflow()
 *       L_abs()
 *       L_add()
 *       L_deposit_h()
 *       L_deposit_l()
 *       L_mac()
 *       L_msu()
 *       L_mult()
 *       L_negate()
 *       L_shift_r()
 *       L_shl()
 *       L_shr()
 *       L_sub()
 *       mac_r()
 *       msu_r()
 *       mult()
 *       mult_r()
 *       negate()
 *       norm_l()
 *       norm_s()
 *       popOverflow()
 *       round32()
 *       saturate()
 *       setOverflow()
 *       shift_r()
 *       shl()
 *       shr()
 *       sub()
 *
 **************************************************************************/

/*_________________________________________________________________________
 |                                                                         |
 |                            Include Files                                |
 |_________________________________________________________________________|
*/

#include "typedefs.h"
#include "mathevrc.h"
//#include <math.h>

/***************************************************************************
 *
 *   FUNCTION NAME: saturate
 *
 *   PURPOSE:
 *
 *     Limit the 32 bit input to the range of a 16 bit word.
 *
 *
 *   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: saturation, limiting, limit, saturate, 16 bits
 *
 *************************************************************************/

static Shortword saturate(Longword L_var1)
{
	Shortword swOut;

	if (L_var1 > SW_MAX)
	{
		swOut = SW_MAX;
		giOverflow = 1;
	}
	else if (L_var1 < SW_MIN)
	{
		swOut = SW_MIN;
		giOverflow = 1;
	}
	else
		swOut = (Shortword) L_var1;		/* automatic type conversion */
	return (swOut);
}

/***************************************************************************
 *
 *   FUNCTION NAME: L_saturate
 *
 *   PURPOSE:
 *
 *     Limit the input double (possibly exceeding 32 bit dynamic
 *     range) having to the 32 output wordsize.
 *
 *   INPUTS:
 *
 *     dVar1
 *                     A double whose range is 
 *                     0x8 0000 0000 <= L_var1 <= 0x7 ffff ffff.
 *                     i.e. a 33 bit number. Not modified.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     L_Out
 *                     32 bit long integer (Longword) where the DSP's
 *                     rules of saturation are followed:
 *                     for: 0x8000 0000 <= dVal1 <= 0x7fff ffff 
 *                      input == output, no saturation
 *                     for: 0x8000 0000 > dVal1 output 0x8000 0000
 *                     for: dVal1 > 0x7fff ffff output 0x7fff ffff
 *
 *   KEYWORDS: saturation, limiting, limit, saturate, 32 bits
 *
 *************************************************************************/

Longword L_saturate(double dVar1)
{
    OP_COUNT(4);        /* Complexity Count -- LT 6/96 */

    if (dVar1 > (double) LW_MAX)
	{
		dVar1 = (double) LW_MAX;
		giOverflow = 1;
	}
	else if (dVar1 < (double) LW_MIN)
	{
		dVar1 = (double) LW_MIN;
		giOverflow = 1;
	}

	return ((long) dVar1);
}

/***************************************************************************
 *
 *   FUNCTION NAME: abs_s
 *
 *   PURPOSE:
 *
 *     Take the absolute value of the 16 bit input.  An input of
 *     -0x8000 results in a return value of 0x7fff.
 *
 *   INPUTS:
 *
 *     var1
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range 0xffff 8000 <= var1 <= 0x0000 7fff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     swOut
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range
 *                     0x0000 0000 <= swOut <= 0x0000 7fff.
 *
 *   IMPLEMENTATION:
 *
 *     Take the absolute value of the 16 bit input.  An input of
 *     -0x8000 results in a return value of 0x7fff.
 *
 *   KEYWORDS: absolute value, abs
 *
 *************************************************************************/

Shortword abs_s(Shortword var1)
{
	Shortword swOut;

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

    if (var1 == SW_MIN)
	{
		swOut = SW_MAX;
		giOverflow = 1;
	}
	else
	{
		if (var1 < 0)
			swOut = -var1;
		else
			swOut = var1;
	}
	return (swOut);
}

/***************************************************************************
 *
 *   FUNCTION NAME: add
 *
 *   PURPOSE:
 *
 *     Perform the addition of the two 16 bit input variable with
 *     saturation.
 *
 *   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.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     swOut
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range
 *                     0xffff 8000 <= swOut <= 0x0000 7fff.
 *
 *   IMPLEMENTATION:
 *
 *     Perform the addition of the two 16 bit input variable with
 *     saturation.
 *
 *     swOut = var1 + var2
 *
 *     swOut is set to 0x7fff if the operation results in an
 *     overflow.  swOut is set to 0x8000 if the operation results
 *     in an underflow.
 *
 *   KEYWORDS: add, addition
 *
 *************************************************************************/

Shortword add(Shortword var1, Shortword var2)
{
	Longword L_sum;
	Shortword swOut;

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

	L_sum = (Longword) var1 + var2;
	swOut = saturate(L_sum);
	return (swOut);
}

/****************************************************************************
 *
 *     FUNCTION NAME: clearOverflow
 *
 *     PURPOSE:
 *
 *        Clear the overflow flag
 *
 *     INPUTS:
 *
 *       none
 *
 *
 *     OUTPUTS:             global overflow flag is cleared
 *                          previous value stored in giOldOverflow
 *
 *     RETURN VALUE:        previous value of overflow
 *                          
 *
 *     KEYWORDS: saturation, limit, overflow
 *
 ***************************************************************************/

int clearOverflow(void)
{

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

	giOldOverflow = giOverflow;
	giOverflow = 0;
	return (giOldOverflow);
}

/***************************************************************************
 *
 *   FUNCTION NAME: divide_s
 *
 *   PURPOSE:
 *
 *     Divide var1 by var2.  Note that both must be positive, and
 *     var1 >=  var2.  The output is set to 0 if invalid input is
 *     provided.
 *
 *   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.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     swOut
 *                     16 bit short signed integer (Shortword) whose value
 *                     falls in the range
 *                     0xffff 8000 <= swOut <= 0x0000 7fff.
 *
 *   IMPLEMENTATION:
 *
 *     In the case where var1==var2 the function returns 0x7fff.  The output
 *     is undefined for invalid inputs.  This implementation returns zero
 *     and issues a warning via stdio if invalid input is presented.
 *
 *   KEYWORDS: divide
 *
 *************************************************************************/

Shortword divide_s(Shortword var1, Shortword var2)
{
	Longword L_div;
	Shortword swOut;


    OP_COUNT(18);        /* Complexity Count -- LT 6/96 */

    if (var1 < 0 || var2 < 0 || var1 > var2)
	{
		/* undefined output for invalid input into divide_s */
		return (0);
	}

	if (var1 == var2)
	{
		giOverflow = 1;
		return (0x7fff);
	}

	L_div = ((0x00008000L * (Longword) var1) / (Longword) var2);
	swOut = saturate(L_div);
	return (swOut);
}

/***************************************************************************
 *
 *   FUNCTION NAME: extract_h
 *
 *   PURPOSE:
 *
 *     Extract the 16 MS bits of a 32 bit Longword.  Return the 16 bit
 *     number as a Shortword.  This is used as a "truncation" of a fractional
 *     number.
 *
 *   INPUTS:
 *
 *     L_var1