The f_read function reads data from a file.
FRESULT f_read ( FIL* FileObject, /* Pointer to the file object structure */ void* Buffer, /* Pointer to the buffer to store read data */ WORD ByteToRead, /* Number of bytes to read */ WORD* ByteRead /* Pointer to the variable to return number of bytes read */ );
The file pointer in the file object increases in number of bytes read. The ByteRead will become less than ByteToRead when the read pointer reached to end of the file or any error occured during the read operation.