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<BODY><PRE>/*___________________________________________________________________________
| |
| |
| Residual Error Insertion Device |
| |
| |
| File : REID.C |
| |
| Date : February 03, 1995 |
| |
| Version: 4.1 |
| |
| |
| Description: |
| ------------ |
| This routine transforms the output file format of the GSM Half |
| Rate Encoder module consisting of: |
| * 18 speech parameters (see GSM TS 06.20) |
| * 1 speech flag SP (see GSM TS 06.41) |
| * 1 voice activity flag VAD (see GSM TS 06.42) |
| |
| to the input file format of the GSM Half Rate Decoder module |
| requiring: |
| * 18 speech parameters (see GSM TS 06.20) |
| * 1 channel condition flag BFI (see GSM TS 06.21, 05.05) |
| * 1 channel condition flag UFI (see GSM TS 06.21, 05.05) |
| * 1 SID flag (2 bits) (see GSM TS 06.41, 05.05) |
| * 1 time alignment flag TAF (see GSM TS 06.41) |
| |
| Between SID updates the speech parameters are replaced by random |
| values simulating an interrupted transmission on the air interface |
| |
| The actual implementation only supports error free transmission (EP0)|
| |
| The shell for the future use of error patterns (residual error |
| pattern insertion) is already included. If necessary, byte swapping |
| is performed on the input speech parameters so that they are always |
| represented internally in PC byte order (assuming that the byte |
| order of the input file is compatible with the machine on which the |
| program is run). However, byte swapping is not done on the flag |
| words (input: SP and VAD, output: BFI, UFI, SID, and TAF). Thus, |
| the residual error pattern insertion code may be written to handle |
| the speech parameter words on a byte basis, but the flag words must |
| always be handled on a word basis. |
|___________________________________________________________________________|
*/
/*___________________________________________________________________________
| |
| Creation: 19.12.94 |
| |
| Changes: |
| 22.12.94: Removal of BCI flag, instead: determination of SID flag |
| 12.01.95: SID update period = 12 (instead of 24) |
| 13.01.95: When in CNI mode, the parameters between SID updates are |
| random values. This simulates the interrupted transmission|
| 03.02.95: Longword main( Longword...) replaced by int main(int ...),|
| initial value of swTAFCnt set to 1 |
|___________________________________________________________________________|
*/
/*___________________________________________________________________________
| |
| Include-Files |
|___________________________________________________________________________|
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "typedefs.h"
#include "reid.h"
/*___________________________________________________________________________
| |
| local Functions |
|___________________________________________________________________________|
*/
/*___________________________________________________________________________
| |
| Subroutines |
|___________________________________________________________________________|
*/
static Longword error_free( FILE *infile, FILE *outfile)
{
#define SPEECH 1
#define CNIFIRSTSID 2
#define CNICONT 3
#define VALIDSID 11
#define GOODSPEECH 33
static Shortword swDecoMode = {SPEECH};
static Shortword swTAFCnt = {1};
Shortword swInPara[20], i, swFrameType;
Shortword swOutPara[22],pswErrorFlag[3];
if( EncoderInterface( infile, swInPara )) return( 1 );
/* Copy input parameters to output parameters (error free transmission) */
/* -------------------------------------------------------------------- */
for (i=0;i<18;i++)
swOutPara[i] = swInPara[i];
/* Set channel status flags (error free transmission) */
/* -------------------------------------------------- */
swOutPara[18] = 0; /* BFI flag */
swOutPara[19] = 0; /* UFI flag */
/* Evaluate SID flag */
/* ----------------- */
pswErrorFlag[0] = 0; /* BFI flag */
pswErrorFlag[1] = 0; /* UFI flag */
pswErrorFlag[2] = 0; /* BCI flag */
swOutPara[20] = swSidDetection(swOutPara, pswErrorFlag);
/* Evaluate TAF flag */
/* ----------------- */
if (swTAFCnt == 0) swOutPara[21] = 1;
else swOutPara[21] = 0;
swTAFCnt = (swTAFCnt + 1) % 12;
/* Frame classification: */
/* Since the transmission is error free, the received frames are either */
/* valid speech or valid SID frames */
/* -------------------------------------------------------------------- */
if ( swOutPara[20] == 2) swFrameType = VALIDSID;
else if ( swOutPara[20] == 0) swFrameType = GOODSPEECH;
else {
printf( "Error in SID detection\n" );
return( 1 );
}
/* Update of decoder state */
/* ----------------------- */
if (swDecoMode == SPEECH) {
if (swFrameType == VALIDSID) swDecoMode = CNIFIRSTSID;
else if (swFrameType == GOODSPEECH) swDecoMode = SPEECH;
}
else { /* comfort noise insertion mode */
if (swFrameType == VALIDSID) swDecoMode = CNICONT;
else if (swFrameType == GOODSPEECH) swDecoMode = SPEECH;
}
/* Replace parameters by random data if in CNICONT-mode and TAF=0 */
/* -------------------------------------------------------------- */
if ((swDecoMode == CNICONT) && (swOutPara[21] == 0)){
RandomParameters(swOutPara);
/* Set flags such, that an "unusable frame" is produced */
swOutPara[18] = 1; /* BFI flag */
swOutPara[19] = 1; /* UFI flag */
swOutPara[20] = 0; /* SID flag */
}
if( outfile ) {
if( WriteOutputFile( swOutPara, outfile )) {
printf( "Error writing File\n" );
return( 1 );
}
}
return( 0 );
}
static Longword EncoderInterface( FILE *infile, Shortword swInPara[] )
{
size_t i = 0;
i = ReadInputFile( swInPara, infile );
return(( i == 0 ) ? 1 : 0 );
}
static size_t ReadInputFile( Shortword buffer[], FILE *fp )
{
size_t i;
i = fread( buffer, sizeof( Shortword ), 20, fp );
SwapBytes( buffer, 18 );
return( i );
}
static size_t WriteOutputFile( Shortword buffer[], FILE *fp )
{
size_t i;
SwapBytes( buffer, 18 );
i = fwrite( buffer, sizeof( Shortword ), 22, fp );
return( ( i == 22 ) ? 0 : 1 );
}
static void SwapBytes( Shortword buffer[], Longword len )
{
Byte *pc, tmp;
Longword i;
if( !ByteOrder())
return;
pc = (Byte *)buffer;
for( i = 0; i < len; i++ ) {
tmp = pc[0];
pc[0] = pc[1];
pc[1] = tmp;
pc += 2;
}
}
static Longword ByteOrder( void )
{
Shortword si;
Byte *pc;
si = 0x1234;
pc = (Byte *)&si;
if (pc[1] == 0x12 && pc[0] == 0x34 )
return( 0 );
if (pc[0] == 0x12 && pc[1] == 0x34 )
return( 1 );
printf( "Error in ByteOrder: %X, %X\n", (int)pc[0], (int)pc[1] );
exit( 1 );
return( 2 );
}
FILE *OpenBinfile( char *name, char *mode )
{
FILE *fp;
if( toupper( *mode ) == 'W' ) { /* Write access */
if(( fp = fopen( name, OPEN_WB )) == NULL ) {
printf( "Can't open output file '%s'\n", name );
exit( 1 );
}
} else { /* Read access */
if(( fp = fopen( name, OPEN_RB )) == NULL ) {
printf( "Can't open file '%s'\n", name );
exit( 1 );
}
}
return( fp );
}
Longword Strincmp( const char *s, const char *t, size_t max )
{
for( ; max > 1; ++s, ++t, --max ) {
if( toupper( *s ) != toupper( *t ))
break;
if( *s == '\0' )
return( 0 );
}
return( toupper( *s ) - toupper( *t ));
}
Longword Stricmp( const char *s, const char *t )
{
for(; toupper( *s ) == toupper( *t ); ++s, ++t ) {
if( *s == '\0' )
return( 0 );
}
return( toupper( *s ) - toupper( *t ));
}
/*************************************************************************
*
* FUNCTION NAME: getPnBits
*
* PURPOSE:
*
* Generate iBits pseudo-random bits using *pL_PNSeed as the
* pn-generators seed.
*
* INPUTS:
*
* iBits - integer indicating how many random bits to return.
* range [0,15], 0 yields 1 bit output
*
* *pL_PNSeed - 32 bit seed (changed by function)
*
* OUTPUTS:
*
* *pL_PNSeed - 32 bit seed, modified.
*
* RETURN VALUE:
*
* random bits in iBits LSB's.
*
*
* IMPLEMENTATION:
*
* implementation of x**31 + x**3 + 1 == PN_XOR_REG | PN_XOR_ADD a
* PN sequence generator using Longwords generating a 2**31 -1
* length pn-sequence.
*
*************************************************************************/
static Shortword getPnBits(Shortword iBits, Longword *pL_PNSeed){
#define PN_XOR_REG (Longword)0x00000005L
#define PN_XOR_ADD (Longword)0x40000000L
Shortword swPnBits=0;
Longword L_Taps,L_FeedBack;
Shortword i;
for (i=0; i < iBits; i++){
/* update the state */
/********************/
L_Taps = *pL_PNSeed & PN_XOR_REG;
L_FeedBack = L_Taps; /* Xor tap bits to yield feedback bit */
L_Taps = L_shr_reid(L_Taps,1);
while(L_Taps){
L_FeedBack = L_FeedBack ^ L_Taps;
L_Taps = L_shr_reid(L_Taps,1);
}
/* LSB of L_FeedBack is next MSB of PN register */
*pL_PNSeed = L_shr_reid(*pL_PNSeed,1);
if (L_FeedBack & 1)
*pL_PNSeed = *pL_PNSeed | PN_XOR_ADD;
/* State update complete.
Get the output bit from the state, add/or it into output */
swPnBits = shl_reid(swPnBits,1);
swPnBits = swPnBits | (*pL_PNSeed & 1);
}
return(swPnBits);
}
/***************************************************************************
*
* FUNCTION NAME: L_shl_reid
*
* PURPOSE:
*
* Arithmetic shift left (or right).
* Arithmetically shift the input left by var2. If var2 is
* negative then an arithmetic shift right (L_shr_reid) of L_var1 by
* -var2 is performed.
*
* INPUTS:
*
* var2
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