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# swap.c

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    00001
    00002 /*
    00003  *   THIS FILE IS UNDER RCS - DO NOT MODIFY UNLESS YOU HAVE
    00004  *   CHECKED IT OUT USING THE COMMAND CHECKOUT.
    00005  *
    00006  *    $Id: swap_8c-source.html,v 1.1 2006/05/19 16:55:02 paulf Exp $
    00007  *
    00008  *    Revision history:
    00009  *     $Log: swap_8c-source.html,v $
    00009  *     Revision 1.1  2006/05/19 16:55:02  paulf
    00009  *     first inclusion
    00009  *
    00010  *     Revision 1.3  2002/03/20 22:13:28  davidk
    00011  *     Modified WaveMsgMakeLocal():
    00012  *      Function now converts the header, performs a checksum on the header,
    00013  *       and then if successful converts the binary data portion of the tracebuf.
    00014  *      Function now returns -2 if the header checksum conversion fails.
    00015  *      Function now returns -1 if _INTEL or _SPARC is not defined.
    00016  *       (Formerly, no conversion was done and success was returned.)
    00017  *
    00018  *     Revision 1.2  2000/06/22 17:49:33  kohler
    00019  *     Modified by WMK to allow in-place swapping of non-byte-alligned data.
    00020  *
    00021  *     Revision 1.1  2000/02/14 18:51:48  lucky
    00022  *     Initial revision
    00023  *
    00024  *
    00025  */
    00026
    00027 /*
    00028  * SWAP.C
    00029  *
    00030  *  Byte swapping functions
    00031  */
    00032
    00033 #include <string.h>
    00034 #include <swap.h>
    00035
    00036 void SwapShort( short *data )
    00037 {
    00038    char temp;
    00039
    00040    union {
    00041       char  c[2];
    00042    } dat;
    00043
    00044    memcpy( &dat, data, sizeof(short) );
    00045    temp     = dat.c[0];
    00046    dat.c[0] = dat.c[1];
    00047    dat.c[1] = temp;
    00048    memcpy( data, &dat, sizeof(short) );
    00049    return;
    00050 }
    00051
    00052 void SwapInt( int *data )
    00053 {
    00054    char temp;
    00055
    00056    union {
    00057       char c[4];
    00058    } dat;
    00059
    00060    memcpy( &dat, data, sizeof(int) );
    00061    temp     = dat.c[0];
    00062    dat.c[0] = dat.c[3];
    00063    dat.c[3] = temp;
    00064    temp     = dat.c[1];
    00065    dat.c[1] = dat.c[2];
    00066    dat.c[2] = temp;
    00067    memcpy( data, &dat, sizeof(int) );
    00068    return;
    00069 }
    00070
    00071
    00072 void SwapLong( long *data )
    00073 {
    00074    char temp;
    00075
    00076    union {
    00077       char c[4];
    00078    } dat;
    00079
    00080    memcpy( &dat, data, sizeof(long) );
    00081    temp     = dat.c[0];
    00082    dat.c[0] = dat.c[3];
    00083    dat.c[3] = temp;
    00084    temp     = dat.c[1];
    00085    dat.c[1] = dat.c[2];
    00086    dat.c[2] = temp;
    00087    memcpy( data, &dat, sizeof(long) );
    00088    return;
    00089 }
    00090
    00091 void SwapDouble( double *data )
    00092 {
    00093    char temp;
    00094
    00095    union {
    00096        char   c[8];
    00097    } dat;
    00098
    00099    memcpy( &dat, data, sizeof(double) );
    00100    temp     = dat.c[0];
    00101    dat.c[0] = dat.c[7];
    00102    dat.c[7] = temp;
    00103
    00104    temp     = dat.c[1];
    00105    dat.c[1] = dat.c[6];
    00106    dat.c[6] = temp;
    00107
    00108    temp     = dat.c[2];
    00109    dat.c[2] = dat.c[5];
    00110    dat.c[5] = temp;
    00111
    00112    temp     = dat.c[3];
    00113    dat.c[3] = dat.c[4];
    00114    dat.c[4] = temp;
    00115    memcpy( data, &dat, sizeof(double) );
    00116    return;
    00117 }
    00118
    00119
    00120 /**************************** swapWaveMsg ***************************
    00121 *       Byte-swap a univerals Waveform message in place.            *
    00122 *       Changes the 'datatype' field in the message header          *
    00123 *       Returns -1 if unknown data type.                            *
    00124 *       Returns -1 if _SPARC or _INTEL not defined.                 *
    00125 *       Returns -2 if checksumish calculation of header fails.      *
    00126 *       Elsewise (SUCCESS) returns 0.                               *
    00127 *********************************************************************/
    00128
    00129 int WaveMsgMakeLocal( TRACE_HEADER* wvmsg )
    00130 {
    00131    int dataSize;  /* flag telling us how many bytes in the data */
    00132    char  byteOrder;
    00133    long* longPtr;
    00134    short* shortPtr;
    00135    int i;
    00136    int nsamp;
    00137    double tShouldEnd;
    00138    double dFudgeFactor;
    00139
    00140    /* See what sort of data it carries
    00141     **********************************/
    00142    dataSize=0;
    00143    if ( strcmp(wvmsg->datatype, "s4")==0)
    00144         {
    00145         dataSize=4; byteOrder='s';
    00146         }
    00147    else if ( strcmp(wvmsg->datatype, "i4")==0)
    00148         {
    00149         dataSize=4; byteOrder='i';
    00150         }
    00151    else if ( strcmp(wvmsg->datatype, "s2")==0)
    00152         {
    00153         dataSize=2; byteOrder='s';
    00154         }
    00155    else if ( strcmp(wvmsg->datatype, "i2")==0)
    00156         {
    00157         dataSize=2; byteOrder='i';
    00158         }
    00159    else
    00160         return(-1); /* We don't know this message type*/
    00161
    00162    /* SWAP the header (if neccessary) */
    00163 #if defined( _SPARC )
    00164    if (byteOrder =='i')
    00165    {
    00166         /* swap the header
    00167         *****************/
    00168         SwapInt( &(wvmsg->pinno) );
    00169         SwapInt( &(wvmsg->nsamp) );
    00170         SwapDouble( &(wvmsg->starttime) );
    00171         SwapDouble( &(wvmsg->endtime) );
    00172         SwapDouble( &(wvmsg->samprate) );
    00173    }
    00174
    00175 #elif defined( _INTEL )
    00176    if (byteOrder =='s')
    00177    {
    00178         /* swap the header
    00179         *****************/
    00180         SwapInt( &(wvmsg->pinno) );
    00181         SwapInt( &(wvmsg->nsamp) );
    00182         SwapDouble( &(wvmsg->starttime) );
    00183         SwapDouble( &(wvmsg->endtime) );
    00184         SwapDouble( &(wvmsg->samprate) );
    00185    }
    00186 #else
    00187         printf( "WaveMsgMakeLocal warning: _INTEL and _SPARC are both undefined." );
    00188         return(-1);
    00189 #endif
    00190
    00191
    00192 /* perform a CheckSumish kind of calculation on the header
    00193     ensure that the tracebuf ends within 5 samples of the given endtime.
    00194     DK 2002/03/18
    00195    *******************************************************************/
    00196   tShouldEnd = wvmsg->starttime + ((wvmsg->nsamp - 1) / wvmsg->samprate);
    00197   dFudgeFactor = 5.0 / wvmsg->samprate;
    00198   if(tShouldEnd != wvmsg->endtime)
    00199   {
    00200     if(tShouldEnd > wvmsg->endtime + dFudgeFactor  &&  tShouldEnd < wvmsg->endtime + dFudgeFactor)
    00201     {
    00202       /* logit("","WaveMsgMakeLocal():  found funky packet with suspect header values!!\n"); */
    00203       return(-2);
    00204     }
    00205   }
    00206
    00207
    00208
    00209    /* SWAP the data (if neccessary) */
    00210 #if defined( _SPARC )
    00211
    00212    if (byteOrder =='i')
    00213    {
    00214 /* Swap the data.  Copy nsamp to a local variable
    00215    to avoid byte misallignment problems.
    00216    **********************************************/
    00217         longPtr=(long*) ((char*)wvmsg + sizeof(TRACE_HEADER) );
    00218         shortPtr=(short*) ((char*)wvmsg + sizeof(TRACE_HEADER) );
    00219         memcpy( &nsamp, &wvmsg->nsamp, sizeof(int) );
    00220         for( i=0; i<nsamp; i++)
    00221                 {
    00222                 if(dataSize==2) SwapShort( &shortPtr[i] );
    00223                 if(dataSize==4) SwapLong(&(longPtr[i]) );
    00224                 }
    00225         /* Re-write the data type field in the message
    00226         **********************************************/
    00227         if(dataSize==2) strcpy(wvmsg->datatype,"s2");
    00228         if(dataSize==4) strcpy(wvmsg->datatype,"s4");
    00229    }
    00230
    00231 #elif defined( _INTEL )
    00232
    00233    if (byteOrder =='s')
    00234    {
    00235 /* Swap the data.  Copy nsamp to a local variable
    00236    to avoid byte misallignment problems.
    00237    **********************************************/
    00238         longPtr=(long*) ((char*)wvmsg + sizeof(TRACE_HEADER) );
    00239         shortPtr=(short*) ((char*)wvmsg + sizeof(TRACE_HEADER) );
    00240         memcpy( &nsamp, &wvmsg->nsamp, sizeof(int) );
    00241         for( i=0; i<nsamp; i++)
    00242                 {
    00243                 if(dataSize==2) SwapShort( &shortPtr[i] );
    00244                 if(dataSize==4) SwapLong(&(longPtr[i]) );
    00245                 }
    00246         /* Re-write the data type field in the message
    00247         **********************************************/
    00248         if(dataSize==2) strcpy(wvmsg->datatype,"i2");
    00249         if(dataSize==4) strcpy(wvmsg->datatype,"i4");
    00250    }
    00251 #else
    00252         printf( "WaveMsgMakeLocal warning: _INTEL and _SPARC are both undefined." );
    00253 #endif
    00254
    00255    return(0);
    00256 }
    00257
    00258
    00259 void SwapFloat( float *data )
    00260 {
    00261    char temp;
    00262
    00263    union {
    00264       char c[4];
    00265    } dat;
    00266
    00267    memcpy( &dat, data, sizeof(float) );
    00268    temp     = dat.c[0];
    00269    dat.c[0] = dat.c[3];
    00270    dat.c[3] = temp;
    00271    temp     = dat.c[1];
    00272    dat.c[1] = dat.c[2];
    00273    dat.c[2] = temp;
    00274    memcpy( data, &dat, sizeof(float) );
    00275    return;
    00276 }
    00277