long ff_ftell( FF_FILE *pxStream );
Returns the current read/write position of an open file in the embedded FAT file system. The position is returned as the number of bytes from the start of the file.
Parameters:
| pxStream | The file being queried. The file must have first been opened using a call to ff_fopen(). |
If pxStream is not NULL then the file's current read/write position is returned. The returned value is the number of bytes the file's read/write position is from the start of the file.
If pxStream is NULL then -1 is returned.
Example usage:
void vSampleFunction( char *pcFileName, char *pcBuffer ) { FF_FILE *pxFile; long lPosition; /* Open the file specified by the pcFileName parameter. */ pxFile = ff_fopen( pcFileName, "r" ); /* Expect the file position to be 0. */ lPosition = ff_ftell( pxFile ); configASSERT( lPosition == 0 ); /* Read one byte. */ ff_fread( pcBuffer, 1, 1, pxFile ); /* Expect the file position to be 1. */ lPosition = ff_ftell( pxFile ); configASSERT( lPosition == 1 ); /* Read another byte. */ ff_fread( pcBuffer, 1, 1, pxFile ); /* Expect the file position to be 2. */ lPosition = ff_ftell( pxFile ); configASSERT( lPosition == 2 ); /* Close the file again. */ ff_fclose( pxFile ); } Example use of the ff_ftell() API function