math_lib.c

It is source code for Melp2.4kps vocoder using dsp tms320vc55x of ti

/*

*2.4 kbps MELP Proposed Federal Standard speech coder
*
*TMS320C5x assembly code
*
*version 1.0
*
*Copyright (c) 1998, Texas Instruments, Inc.  
*
*Texas Instruments has intellectual property rights on the MELP
*algorithm.  The Texas Instruments contact for licensing issues for
*commercial and non-government use is William Gordon, Director,
*Government Contracts, Texas Instruments Incorporated, Semiconductor
*Group (phone [phone]).

*/

/*************************************************************************
*
* The following code was hand optimized for the Texas Instuments
* TMS320C5x DSP by DSPCon, Inc.  For information, please contact DSPCon
* at:
* 
*                       DSPCon, Inc.
*                       380 Foothill Road
*                       Bridgewater, New Jersey 08807
*                       [phone]
*                       [e-mail]
*                       www.dspcon.com
*
*************************************************************************/




#include <math.h>
#include "spbstd.h"
#include "mathhalf.h"
#include "mathdp31.h"
#include "math_lib.h"

extern int saturation;

Shortword DEBUG;

#define X05_Q15    (Shortword)(0.5*((Longword)1<<15))
#define ONE_Q15    (Shortword)(((Longword)1<<15)-1)
#define PI_Q13     M_PI*(1<<13)



/***************************************************************************
 *
 *   FUNCTION NAME: L_pow_fxp
 *
 *   PURPOSE:
 *
 *     Compute the value of x raised to the power 'power'.
 *
 *
 *   INPUTS:
 *
 *     x
 *                     32 bit long signed integer (Longword).
 *     power
 *                     16 bit short signed integer (Shortword) in Q15.
 *     Q_in
 *                     16 bit short signed integer (Shortword) represents
 *                     Q value of x.
 *     Q_out
 *                     16 bit short signed integer (Shortword) represents
 *                     required Q value of returned result.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     temp
 *                     16 bit short signed integer (Shortword).
 *
 *************************************************************************/
Shortword L_pow_fxp(Longword x,Shortword power,Shortword Q_in,Shortword Q_out)
{
  Shortword temp;

  /* increment complexity for if statement */
  
  if (!x)
    return((Shortword)0);

  temp = L_log10_fxp(x,Q_in);   /* temp in Q11 */
  temp = mult(power,shl(temp,1));       /* temp in Q12 */
  temp = pow10_fxp(temp,Q_out);
  return (temp);
}