tomwalters@0: /*
tomwalters@0:     swab.c      swap bytes
tomwalters@0:     ------
tomwalters@0: 
tomwalters@0:   Read and write binary shorts (2-bytes).
tomwalters@0:   With no filename arguments, data is expected on the stdin, and the
tomwalters@0:   result is written on the stdout. Otherwise each given filename is
tomwalters@0:   processed in turn. When the `output' option is "off" output overwrites the
tomwalters@0:   respective input file. (The respective output for the stdin is the stdout).
tomwalters@0:   Otherwise all results are written to the one given output file
tomwalters@0:   (which is the stdout by default).
tomwalters@0: 
tomwalters@0: */
tomwalters@0: 
tomwalters@0: #include <stdio.h>
tomwalters@0: #include <math.h>
tomwalters@0: #include "options.h"
tomwalters@0: 
tomwalters@0: 
tomwalters@0: char applic[]     = "Swap byte order of binary 2-byte data." ;
tomwalters@0: 
tomwalters@0: static char *helpstr,   *outstr,  *sizestr  ;
tomwalters@0: 
tomwalters@0: static Options option[] = {
tomwalters@0:     {   "help"      ,   "off"       ,  &helpstr     ,   "help"                                      , DEBUG   },
tomwalters@0:     {   "output"    ,   "stdout"    ,  &outstr      ,   "output filename (off = overwrite input)"   , VAL     },
tomwalters@0:     {   "SIZE"      ,   "262144"    ,  &sizestr     ,   "buffer size in bytes"                      , SVAL    },
tomwalters@0:    ( char * ) 0 } ;
tomwalters@0: 
tomwalters@0: 
tomwalters@0: int    SIZE        ;    /* size of temp buffer for stdin data      */
tomwalters@0: 
tomwalters@0: main(argc, argv)
tomwalters@0: int   argc ;
tomwalters@0: char *argv[] ;
tomwalters@0: {
tomwalters@0:     FILE *ifp, *ofp ;
tomwalters@0:     int   i, j, n, doOpen, doCreate  ;
tomwalters@0:     char *data, *Y ;
tomwalters@0: 
tomwalters@0:     i = getopts( option, argc, argv ) ;
tomwalters@0:     if ( !isoff( helpstr ) )
tomwalters@0: 	helpopts( helpstr, argv[0], applic, option ) ;
tomwalters@0: 
tomwalters@0:     SIZE  = atoi( sizestr ) ;
tomwalters@0: 
tomwalters@0:     doOpen = doCreate = 0 ;
tomwalters@0: 
tomwalters@0:     if ( i == 0 ) ifp = stdin ;
tomwalters@0:     else doOpen++ ;
tomwalters@0: 
tomwalters@0:     if ( isoff( outstr ) ) {
tomwalters@0: 	if ( i == 0 )   ofp = stdout ;  /* o/p = i/p which is stdin   */
tomwalters@0: 	else            doCreate++ ;    /* o/p = i/p for current file */
tomwalters@0:     }
tomwalters@0:     else if ( isstr( outstr, "stdout") ) ofp = stdout ;
tomwalters@0:     else if ( ( ofp = fopen( outstr, "w" ) ) == (FILE *)0 ) {
tomwalters@0: 	fprintf( stderr,"swab: can't create %s\n", outstr ) ;
tomwalters@0: 	exit( 1 ) ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     Y = (char *)malloc( sizeof( short ) ) ;
tomwalters@0:     if ( ( data = (char *)malloc( SIZE ) ) == NULL ) {
tomwalters@0: 	fprintf( stderr, "malloc out of space\n" ) ;
tomwalters@0: 	exit( 1 ) ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     do {
tomwalters@0: 
tomwalters@0: 	if ( doOpen   && ( ifp = fopen( argv[argc-i], "r" ) ) == (FILE *)0 ) {
tomwalters@0: 	    fprintf( stderr,"swab: can't open %s\n", argv[argc-i] ) ;
tomwalters@0: 	    exit( 1 ) ;
tomwalters@0: 	}
tomwalters@0: 
tomwalters@0: 	for ( n = 0 ; n < SIZE && fread( &data[n], sizeof(short), 1, ifp ) ; n += 2 )
tomwalters@0: 	    ;
tomwalters@0: 	if ( n == SIZE ) fprintf( stderr, "warning: buffer out of space, increase SIZE\n" ) ;
tomwalters@0: 
tomwalters@0: 	if ( doOpen   ) fclose( ifp ) ;
tomwalters@0: 
tomwalters@0: 	if ( doCreate && ( ofp = fopen( argv[argc-i], "w" ) ) == (FILE *)0 ) {
tomwalters@0: 	    fprintf( stderr,"swab: can't create %s\n", argv[argc-i] ) ;
tomwalters@0: 	    exit( 1 ) ;
tomwalters@0: 	}
tomwalters@0: 
tomwalters@0: 	for ( j = 0 ; j < n ; j += 2 ) {
tomwalters@0: 	    *Y     = data[j+1] ;
tomwalters@0: 	    *(Y+1) = data[j]   ;
tomwalters@0: 	    fwrite( Y, sizeof(short), 1, ofp );
tomwalters@0: 	}
tomwalters@0: 
tomwalters@0: 	if ( doCreate ) fclose( ofp ) ;
tomwalters@0: 
tomwalters@0:     } while ( --i > 0 ) ;
tomwalters@0: 
tomwalters@0: }
tomwalters@0: