tty_hdr.c

完整的EVRC压缩解压缩算法源码,通过C-C++编译后可以运行!

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/* committee as a basis for discussion and should not be considered  */
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/* Specifically, Motorola Inc. reserves the right to modify, amend,  */
/* or withdraw the statement contained herein. Permission is granted */
/* to 3GPP2 and its organizational partners to copy any portion of   */
/* this document for the legitimate purposes of the 3GPP2.  Copying  */
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#include <stdio.h>
#include "typedef.h"
#include "tty.h"
#include "basic_op.h"

/***********************************************************************
*   tty_header_in()
*       Takes the header coming into the tty processing and converts
*       it to the internal format.
************************************************************************/

void tty_header_in( Word16 *counter )
{
    Word16   i;
    Word16   j;
    
  
    if( sub(*counter,TTY_SILENCE_HDR) == 0 )
    {
        *counter = TTY_SILENCE;
    }
    else if( sub(*counter,TTY_ONSET_HDR) == 0 )
    {
        *counter = TTY_ONSET;
    }
    else
    {
        j = TTY_CHAR_HDR_START;                     
        for( i=TTY_COUNTER_START ; i <= TTY_COUNTER_STOP ; i = shl(i,1) )
        {
            if( sub(*counter,j) == 0 )
            {
                *counter = i;                       
                break;
            }
            j = add(j,1);
        }
    }

} /* end tty_header_in() */


/***********************************************************************
*   tty_header_in()
*       Takes the internal counter coming out of the tty processing
*       and converts it to the external header format that is sent
*       in the speech packet.
************************************************************************/

void tty_header_out( Word16 *counter)
{
    Word16   i;
    Word16   j;

    if( sub(*counter,NON_TTY) == 0 )
    {
        return;
    }

    if( sub(*counter,TTY_ONSET) == 0 )
    {
        *counter = TTY_ONSET_HDR;                   
        return;
    }

    if( sub(*counter,TTY_SILENCE) == 0 )
    {
        *counter = TTY_SILENCE_HDR;                 
        return;
    }

    j = TTY_CHAR_HDR_START;                     
    for( i=TTY_COUNTER_START ; i <= TTY_COUNTER_STOP ; i = shl(i,1) )
    {
                                                
        if( sub(*counter,i) == 0 )
        {
            *counter = j;                       
            break;
        }
        j = add(j,1);
    }

    return;

} /* end tty_header_out() */