basop32.c

G.722.1 fixed codec arithmetic

/*                                                      v.1.0 - 26.Jan.2000
  =============================================================================

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                   ========================================
                    ITU-T - USER'S GROUP ON SOFTWARE TOOLS
                   ========================================

       =============================================================
       COPYRIGHT NOTE: This source code, and all of its derivations,
       is subject to the "ITU-T General Public License". Please have
       it  read  in    the  distribution  disk,   or  in  the  ITU-T
       Recommendation G.191 on "SOFTWARE TOOLS FOR SPEECH AND  AUDIO
       CODING STANDARDS".
       =============================================================

MODULE:         BASOP, BASIC OPERATORS

ORIGINAL BY:
                Incorporated from anonymous contributions for 
                ETSI Standards as well as G.723.1, G.729, and G.722.1

DESCRIPTION:
        This file contains the definition of 16- and 32-bit basic
        operators to be used in the implementation of signal
        processing algorithms. The basic operators try to resemble
        assembly language instructions that are commonly found in
        digital signal processor (DSP) CPUs, thus allowing algorithm
        C-code implementations more directly mapeable to DSP assembly
        code.

        *********************************************************
         NOTE: so far, this module does not have a demo program!
        *********************************************************

FUNCTIONS:
  Defined in basop.h. Self-documentation within each function.

HISTORY:
  26.Jan.00	v1.0	Incorporated to the STL from updated G.723.1/G.729 
                        basic operator library (based on basicop2.c) and 
                        G.723.1's basop.c [L_mls(), div_l(), i_mult()]
  05.Jul.00     v1.1    Added 32-bit shiftless accumulation basic 
                        operators (L_msu0, L_mac0, L_mult0). Improved
                        documentation for i_mult().
  =============================================================================
*/

/*___________________________________________________________________________
 |                                                                           |
 | Basic arithmetic operators.                                               |
 |                                                                           |
 | $Id $
 |___________________________________________________________________________|
*/

/*___________________________________________________________________________
 |                                                                           |
 |   Include-Files                                                           |
 |___________________________________________________________________________|
*/

#include <stdio.h>
#include <stdlib.h>
#include "typedef.h"
#include "basop32.h"

#if (WMOPS)
#include "count.h"
extern BASIC_OP multiCounter[MAXCOUNTERS];
extern int currCounter;

#endif

/*___________________________________________________________________________
 |                                                                           |
 |   Local Functions                                                         |
 |___________________________________________________________________________|
*/
Word16 saturate (Word32 L_var1);

/*___________________________________________________________________________
 |                                                                           |
 |   Constants and Globals                                                   |
 |___________________________________________________________________________|
*/
Flag Overflow = 0;
Flag Carry = 0;

/*___________________________________________________________________________
 |                                                                           |
 |   Functions                                                               |
 |___________________________________________________________________________|
*/

/*___________________________________________________________________________
 |                                                                           |
 |   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 (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 saturate (Word32 L_var1)
{
    Word16 var_out;

    if (L_var1 > 0X00007fffL)
    {
        Overflow = 1;
        var_out = MAX_16;
    }
    else if (L_var1 < (Word32) 0xffff8000L)
    {
        Overflow = 1;
        var_out = MIN_16;
    }
    else
    {
        var_out = extract_l (L_var1);
#if (WMOPS)
        multiCounter[currCounter].extract_l--;
#endif
    }

    return (var_out);
}
/* ------------------------- End of saturate() ------------------------- */


/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : add                                                     |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |    Performs the addition (var1+var2) with overflow control and saturation;|
 |    the 16 bit result is set at +32767 when overflow occurs or at -32768   |
 |    when underflow occurs.                                                 |
 |                                                                           |
 |   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 add (Word16 var1, Word16 var2)
{
    Word16 var_out;
    Word32 L_sum;

    L_sum = (Word32) var1 + var2;
    var_out = saturate (L_sum);
#if (WMOPS)
    multiCounter[currCounter].add++;
#endif
    return (var_out);
}
/* ------------------------- End of add() ------------------------- */


/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : sub                                                     |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |    Performs the subtraction (var1+var2) with overflow control and satu-   |
 |    ration; the 16 bit result is set at +32767 when overflow occurs or at  |
 |    -32768 when underflow occurs.                                          |
 |                                                                           |
 |   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 sub (Word16 var1, Word16 var2)
{
    Word16 var_out;
    Word32 L_diff;

    L_diff = (Word32) var1 - var2;
    var_out = saturate (L_diff);
#if (WMOPS)
    multiCounter[currCounter].sub++;
#endif
    return (var_out);
}
/* ------------------------- End of sub() ------------------------- */


/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : abs_s                                                   |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |    Absolute value of var1; abs_s(-32768) = 32767.                         |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |