agc.cpp

实现3GPP的GSM中AMR语音的CODECS。

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 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied.
 * See the License for the specific language governing permissions
 * and limitations under the License.
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 */
/****************************************************************************************
Portions of this file are derived from the following 3GPP standard:

    3GPP TS 26.073
    ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec
    Available from http://www.3gpp.org

(C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC)
Permission to distribute, modify and use this file under the standard license
terms listed above has been obtained from the copyright holder.
****************************************************************************************/
/*
------------------------------------------------------------------------------



 Pathname: ./audio/gsm-amr/c/src/agc.c
 Funtions: energy_old
           energy_new
           agc_init
           agc_reset
           agc_exit
           agc
           agc2

     Date: 03/28/2000

------------------------------------------------------------------------------
 REVISION HISTORY

 Description: Fixed some problems with overflow and negative saturation.

 Description: Made changes based on comments from the review meeting. Removed
    more calls to L_shl in agc and agc2.

 Description: Synchronized code with the UMTS version 3.2.0. Updated Pseudo-
              code section on all functions to show the latest version of
              code that was optimized. Removed hard tabs. Updated to most
              current PV coding template.

 Description: Removed basic_op.h and replaced it with the header files of
              the math functions used by the file. Removed unnecessary
              include files.

 Description: Made the following changes per comments from Phase 2/3 review:
              1. Changed FOR loops to count down.
              2. Reordered IF statement to take advantage of branch prediction.
              3. Declared one local variable per line.
              4. Copied detailed function description of agc() from the
                 header file.
              5. Made minor cosmetic changes.
              6. Fixed typecasting issue using a TI C compiler.

 Description: Made the following changes to make the library EPOC compatible.
             1. energy_old(): Passed in pointer to overflow flag. Changed
              call to L_add() to include overflow flag.
              2. energy_new(): Passed in pointer to overflow flag. Changed
              function calls to L_add() and energy_old() to include overflow
              flag.
              3. agc(): Passed in pointer to overflow flag. Changed function
              calls to energy_new(), L_shl(), round(), L_shr(), Inv_sqrt(),
              mult(), add() and L_mult() to include overflow flag.
              3. agc2(): Passed in pointer to overflow flag. Changed function
              calls to energy_new(), L_shl(), round(), L_shr(), Inv_sqrt(),
              mult(), add() and L_mult() to include overflow flag.

 Description: Added wrapper functions for energy_old() and energy_new() for
             access by unit tests.
 Description: Corrected return type for energy_old() and energy_new() wrapper
              functions. Removed unneeded header files. Cleaned up code.

 Description: Fixed bug found in the FOR loop calculation of gain[n] in agc().
              Updated copyright year.

 Description: Removed the functions agc_init() and agc_exit().  The agc
 related structure is no longer dynamically allocated.

 Description: Updated Ouputs section for all functions.

 Description: Optimized agc() to reduce clock cycle usage. Updated
              copyright year and removed unused files in Include section.

 Description: Changed function name to pv_round to avoid conflict with
              round function in C standard library.

 Description: Removed the usage of l_deposit_l().

 Description:

------------------------------------------------------------------------------
 MODULE DESCRIPTION

 This set of modules scale the excitation level and output of the speech
 signals.

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


/*----------------------------------------------------------------------------
; INCLUDES
----------------------------------------------------------------------------*/

#include    "agc.h"
#include    "cnst.h"
#include    "inv_sqrt.h"
#include    "basic_op.h"

/*----------------------------------------------------------------------------
; MACROS
; Define module specific macros here
----------------------------------------------------------------------------*/


/*----------------------------------------------------------------------------
; DEFINES
; Include all pre-processor statements here. Include conditional
; compile variables also.
----------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------
; LOCAL FUNCTION DEFINITIONS
; Function Prototype declaration
----------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------
; LOCAL VARIABLE DEFINITIONS
; Variable declaration - defined here and used outside this module
----------------------------------------------------------------------------*/

/*
------------------------------------------------------------------------------
 FUNCTION NAME: energy_old
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    in = input signal (Word16)
    l_trm = input signal length (Word16)
    pOverflow = address of overflow (Flag)

 Outputs:
    pOverflow -> 1 if the energy computation saturates

 Returns:
    s = return energy of signal (Word32)

 Global Variables Used:
    None.

 Local Variables Needed:
    None.

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

 Returns the energy of the signal.

------------------------------------------------------------------------------
 REQUIREMENTS

 None.

------------------------------------------------------------------------------
 REFERENCES

 agc.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

static Word32 energy_old( // o : return energy of signal
    Word16 in[],          // i : input signal (length l_trm)
    Word16 l_trm          // i : signal length
)
{
    Word32 s;
    Word16 i, temp;

    temp = shr (in[0], 2);
    s = L_mult (temp, temp);

    for (i = 1; i < l_trm; i++)
    {
        temp = shr (in[i], 2);
        s = L_mac (s, temp, temp);
    }

    return s;
}

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

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

static Word32 energy_old(       /* o : return energy of signal      */
    Word16 in[],        /* i : input signal (length l_trm)  */
    Word16 l_trm,       /* i : signal length                */
    Flag   *pOverflow   /* overflow: flag to indicate overflow */
)

{
    Word32  s = 0;
    Word32  L_temp;
    Word16  i;
    Word16  temp;

    for (i = l_trm - 1; i >= 0; i--)
    {
        temp = in[i];
        if (temp < 0)
        {
            temp = ~(~temp >> 2);
        }
        else
        {
            temp = temp >> 2;
        }
        L_temp = (((Word32) temp) * temp) << 1;
        s = L_add(s, L_temp, pOverflow);
    }

    return(s);
}

/*----------------------------------------------------------------------------*/
/*
------------------------------------------------------------------------------
 FUNCTION NAME: energy_old__Wrapper
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    in = input signal (Word16)
    l_trm = input signal length (Word16)
    pOverflow = address of overflow (Flag)
 Outputs:
    pOverflow -> 1 if the energy computation saturates

 Returns:
    s = return energy of signal (Word32)

 Global Variables Used:
    None.

 Local Variables Needed:
    None.

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

 This function provides external access to the static function energy_old.

------------------------------------------------------------------------------
 REQUIREMENTS

 None

------------------------------------------------------------------------------
 REFERENCES

 None

------------------------------------------------------------------------------
 PSEUDO-CODE

 CALL energy_old (  in = in
            l_trm = l_trm
            pOverflow = pOverflow )
   MODIFYING(nothing)
   RETURNING(energy_old_value = s)

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

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

Word32 energy_old_Wrapper(Word16 in[], Word16 l_trm, Flag *pOverflow)
{
    Word32 energy_old_value;

    /*----------------------------------------------------------------------------
     CALL energy_old (  in = in
                l_trm = l_trm
                pOverflow = pOverflow )

      MODIFYING(nothing)
       RETURNING(energy_old_value = s)
    ----------------------------------------------------------------------------*/
    energy_old_value = energy_old(in, l_trm, pOverflow);
    return(energy_old_value);
}
/*--------------------------------------------------------------------------*/

/*
-----------------------------------------------------------------------------
 FUNCTION NAME: energy_new
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    in = input signal
    l_trm = input signal length
    pOverflow = address of overflow (Flag)

 Outputs:
    pOverflow -> 1 if the energy computation saturates

 Returns:
    s = return energy of signal

 Global Variables Used:
    None.

 Local Variables Needed:
    None.

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

 Returns the energy of the signal.

------------------------------------------------------------------------------
 REQUIREMENTS

 None.

------------------------------------------------------------------------------
 REFERENCES