math_ext32.c

EVRC是用于高通公司的语音编码

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/*-------------------------------------------------------------------*/


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

#include "typedef_fx.h"
#include "basic_op.h"

#ifdef WMOPS_FX
#include "main_fx.h"
#include "const_fx.h"
#include "ext_var_fx.h"
#endif

/*_________________________________________________________________________
 |                                                                         |
 |                                  Define                                 |
 |_________________________________________________________________________|
*/

#define SW_MIN (short)0x8000           /* smallest Ram */
#define SW_MAX (short)0x7fff           /* largest Ram */

/*_________________________________________________________________________
 |                                                                         |
 |                                Functions                                |
 |_________________________________________________________________________|
*/

/****************************************************************************
 *
 *     FUNCTION NAME: L_mpy_ll
 *
 *     PURPOSE:    Multiply a 32 bit number (L_var1) and a 32 bit number
 *                 (L_var2), and return a 32 bit result.
 *
 *     INPUTS:
 *
 *       L_var1             A Word32 input variable
 *
 *       L_var2             A Word32 input variable
 *
 *     OUTPUTS:             none
 *
 *     IMPLEMENTATION:
 *
 *        Performs a 31x31 bit multiply, Complexity=24 Ops.
 *
 *        Let x1x0, or y1y0, be the two constituent halves
 *        of a 32 bit number.  This function performs the
 *        following:
 *
 *        low = ((x0 >> 1)*(y0 >> 1)) >> 16     (low * low)
 *        mid1 = [(x1 * (y0 >> 1)) >> 1 ]       (high * low)
 *        mid2 = [(y1 * (x0 >> 1)) >> 1]        (high * low)
 *        mid =  (mid1 + low + mid2) >> 14      (sum so far)
 *        output = (y1*x1) + mid                (high * high)
 *
 *
 *     RETURN VALUE:        A Word32 value
 *
 *     KEYWORDS: mult,mpy,multiplication
 *
 ***************************************************************************/

Word32 L_mpy_ll(Word32 L_var1, Word32 L_var2)
        {
	  Word16 swLow1,
	         swLow2,
	         swHigh1,
	         swHigh2;
	  Word32 L_varOut,
	         L_low,
	         L_mid1,
	         L_mid2,
	         L_mid;
	  
#ifdef WMOPS_FX
	  counter_fx.L_mpy_ll++;

	  counter_fx.shr -= 2; 
	  counter_fx.extract_l -= 2;
	  counter_fx.extract_h -= 2;
	  counter_fx.L_mult -= 3;
	  counter_fx.L_shr -= 4;
	  counter_fx.L_add -= 2;
	  counter_fx.L_mac--;
#endif
	  
	  swLow1 = shr(extract_l(L_var1), 1);
	  swLow1 = SW_MAX & swLow1;
	  
	  swLow2 = shr(extract_l(L_var2), 1);
	  swLow2 = SW_MAX & swLow2;
	  swHigh1 = extract_h(L_var1);
	  swHigh2 = extract_h(L_var2);
	  
	  L_low = L_mult(swLow1, swLow2);
	  L_low = L_shr(L_low, 16);
	  
	  L_mid1 = L_mult(swHigh1, swLow2);
	  L_mid1 = L_shr(L_mid1, 1);
	  L_mid = L_add(L_mid1, L_low);
	  
	  L_mid2 = L_mult(swHigh2, swLow1);
	  L_mid2 = L_shr(L_mid2, 1);
	  L_mid = L_add(L_mid, L_mid2);
	  
	  L_mid = L_shr(L_mid, 14);
	  L_varOut = L_mac(L_mid, swHigh1, swHigh2);
	  
	  return (L_varOut);
	}

/*----------------------------------------------------------------------------*/

/****************************************************************************
 *
 *     FUNCTION NAME: L_mpy_ls
 *
 *     PURPOSE:    Multiply a 32 bit number (L_var2) and a 16 bit
 *                 number (var1) returning a 32 bit result. L_var2
 *                 is truncated to 31 bits prior to executing the
 *                 multiply.
 *
 *     INPUTS:
 *
 *       L_var2             A Word32 input variable
 *
 *       var1               A Word16 input variable
 *
 *     OUTPUTS:             none
 *
 *     RETURN VALUE:        A Word32 value
 *
 *     KEYWORDS: mult,mpy,multiplication
 *
 ***************************************************************************/

Word32 L_mpy_ls(Word32 L_var2, Word16 var1)
        {
	  Word32 L_varOut;
	  Word16 swtemp;

#ifdef WMOPS_FX
	  counter_fx.L_mpy_ls++;

	  counter_fx.shr--; 
	  counter_fx.extract_l--;
	  counter_fx.L_mult--;
	  counter_fx.L_shr--;
	  counter_fx.L_mac--;
#endif
	  
	  swtemp = shr(extract_l(L_var2), 1);
	  swtemp = (short) 32767 & (short) swtemp;
	  
	  L_varOut = L_mult(var1, swtemp);
	  L_varOut = L_shr(L_varOut, 15);
	  L_varOut = L_mac(L_varOut, var1, extract_h(L_var2));

	  return (L_varOut);

	}