PropWare::FatFileReader Class Reference

Read a file on a FAT 16 or FAT 32 storage device. More...

#include <PropWare/filesystem/fat/fatfilereader.h>

Inheritance diagram for PropWare::FatFileReader:

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Public Types
enum	ErrorCode {   NO_ERROR = 0,   BEG_ERROR = Filesystem::END_ERROR + 1,   ENTRY_NOT_FILE = BEG_ERROR,   FILENAME_NOT_FOUND,   END_ERROR = FILENAME_NOT_FOUND }
enum	SeekDir {   SeekDir::BEG,   SeekDir::CUR,   SeekDir::END }

Public Member Functions
	FatFileReader (FatFS &fs, const char name[], BlockStorage::Buffer &buffer=SHARED_BUFFER, const Printer &logger=pwOut)
	Construct a new file instance. More...
PropWare::ErrorCode	open ()
	Open the file. More...
PropWare::ErrorCode	safe_get_char (char &c)
	Read a character from the file. More...
const char *	get_name () const
	Determine the name of a file. More...
bool	exists () const
	Determine if a file exists (file does not have to be open) More...
bool	exists (PropWare::ErrorCode &err) const
virtual PropWare::ErrorCode	close ()
	Close a file - a required step in any workflow that includes opening a file. More...
virtual PropWare::ErrorCode	flush ()=0
	Flush any modified data back to the SD card. More...
int32_t	get_length () const
	Return the number of bytes (characters) in the file.
int32_t	tell () const
	Obtain the value of the file position indicator. More...
PropWare::ErrorCode	seek (const int32_t offset, const SeekDir way)
	Sets the position of the next character to be read or written. More...
PropWare::ErrorCode	seek (const int32_t position)
PropWare::ErrorCode	flush ()
	Flush any modified data back to the SD card. More...
char	get_char ()
	Read a character from the file. More...
bool	eof () const
	Determine whether the read pointer has reached the end of the file. More...
PropWare::ErrorCode	safe_peek (char &c)
	Read a character from the file without incrementing the pointer. More...
char	peek ()
	Read a character from the file without incrementing the pointer. More...
PropWare::ErrorCode	get_error () const
	Get the latest error that occurred during an unsafe method call. More...

Static Public Attributes
static const unsigned int	MAX_FILENAME_LENGTH = 32

Detailed Description

Read a file on a FAT 16 or FAT 32 storage device.

A file can be echoed to the terminal with a simple program such as

int main () {
    const SD driver;
    FatFS filesystem(&driver);
    filesystem.mount();
 
    FatFileReader reader(filesystem, "fat_test.txt");
    reader.open();
 
    while (!reader.eof())
        pwOut << reader.get_char();
 
    return 0;
}

It can also be hooked up to the PropWare::Scanner class for line-by-line or formatted reading:

int main () {
    const SD driver;
    FatFS filesystem(&driver);
    filesystem.mount();
 
    FatFileReader reader(filesystem, "fat_test.txt");
    reader.open();
 
    Scanner fileScanner(&reader);
    char buffer[256];
    while (!reader.eof()) {
        fileScanner.gets(buffer, 256);
        pwOut.println(buffer);
    }
 
    return 0;
}

Examples

FileReader_Demo.cpp, and FileWriter_Demo.cpp.

Definition at line 79 of file fatfilereader.h.

Member Enumeration Documentation

ErrorCode

enum PropWare::FatFile::ErrorCode

inherited

Enumerator
ENTRY_NOT_FILE	FatFile Error 0
FILENAME_NOT_FOUND	FatFile Error 1

Definition at line 38 of file fatfile.h.

SeekDir

enum PropWare::File::SeekDir

stronginherited

Enumerator
BEG	beginning of the stream
CUR	current position in the stream
END	end of the stream

Definition at line 47 of file file.h.

Constructor & Destructor Documentation

FatFileReader()

PropWare::FatFileReader::FatFileReader	(	FatFS &	fs,
		const char	name[],
		BlockStorage::Buffer &	buffer = SHARED_BUFFER,
		const Printer &	logger = pwOut
	)

Construct a new file instance.

Parameters

[in]	fs	The filesystem is needed for opening the file
[in]	name	Name of the file to open - it must exist in the current working directory (see issue 55 for opening from a relative or absolute path)
[in]	*buffer	Address of a dedicated buffer that should be used for this file. If left as the NULL (the default), a shared buffer will be used.
[in]	logger	This is only used for printing debug statements. Use of the logger is limited such that all references will be optimized out in normal application code

Definition at line 93 of file fatfilereader.h.

Member Function Documentation

close()

virtual PropWare::ErrorCode PropWare::File::close ( )

virtualinherited

Close a file - a required step in any workflow that includes opening a file.

Returns

0 upon success, error code otherwise

Definition at line 74 of file file.h.

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eof()

bool PropWare::FileReader::eof ( ) const

inherited

Determine whether the read pointer has reached the end of the file.

Returns

Returns true if the pointer points to the end of the file, false otherwise

Definition at line 75 of file filereader.h.

exists() [1/2]

bool PropWare::FatFile::exists ( ) const

inherited

Determine if a file exists (file does not have to be open)

Returns

True if the file exists, false otherwise

Definition at line 62 of file fatfile.h.

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exists() [2/2]

bool PropWare::FatFile::exists ( PropWare::ErrorCode &  err ) const

inherited

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

[out]

err

It is possible for an error to occur

Definition at line 72 of file fatfile.h.

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flush() [1/2]

PropWare::ErrorCode PropWare::FileReader::flush ( )

virtualinherited

Flush any modified data back to the SD card.

Returns

0 upon success, error code otherwise

Implements PropWare::File.

Definition at line 40 of file filereader.h.

flush() [2/2]

virtual PropWare::ErrorCode PropWare::File::flush ( )

pure virtualinherited

Flush any modified data back to the SD card.

Returns

0 upon success, error code otherwise

Implemented in PropWare::FatFileWriter, and PropWare::FileReader.

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get_char()

char PropWare::FileReader::get_char ( )

virtualinherited

Read a character from the file.

Postcondition

If an error occurs, you can retrieve the error code via FileReader::get_error()

Returns

Character upon success, -1 otherwise

Implements PropWare::ScanCapable.

Definition at line 60 of file filereader.h.

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get_error()

PropWare::ErrorCode PropWare::FileReader::get_error ( ) const

inherited

Get the latest error that occurred during an unsafe method call.

Methods such as FileReader::get_char() would normally throw an exception if an error occurred in a C++ program, but due to size constraints, exceptions are not used by PropWare. Therefore, any error that is occurs in a function that does not return ErrorCode simply saves the error to the internal state and returns a known value.

Returns

Most recent error code

Definition at line 115 of file filereader.h.

get_name()

const char* PropWare::FatFile::get_name ( ) const

inherited

Determine the name of a file.

Returns

Character array containing the file - DO NOT modify the array, it will modify the internals of the file instance

Definition at line 53 of file fatfile.h.

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open()

PropWare::ErrorCode PropWare::FatFileReader::open ( )

virtual

Open the file.

Returns

0 upon success, error code otherwise

Implements PropWare::File.

Definition at line 100 of file fatfilereader.h.

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peek()

char PropWare::FileReader::peek ( )

inherited

Read a character from the file without incrementing the pointer.

Postcondition

If an error occurs, you can retrieve the error code via FileReader::get_error()

Returns

Character upon success, -1 otherwise

Definition at line 99 of file filereader.h.

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safe_get_char()

PropWare::ErrorCode PropWare::FatFileReader::safe_get_char ( char &  c )

virtual

Read a character from the file.

Parameters

[out]

c

Character from file will be stored into c

Returns

0 upon success, error code otherwise

Implements PropWare::FileReader.

Definition at line 115 of file fatfilereader.h.

safe_peek()

PropWare::ErrorCode PropWare::FileReader::safe_peek ( char &  c )

inherited

Read a character from the file without incrementing the pointer.

Parameters

[out]

c

Character from file will be stored into c

Returns

0 upon success, error code otherwise

Definition at line 86 of file filereader.h.

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seek() [1/2]

PropWare::ErrorCode PropWare::File::seek ( const int32_t  offset, const SeekDir  way  )

inherited

Sets the position of the next character to be read or written.

Parameters

[in]	offset	Offset value, relative to the way parameter
[in]	way	Starting position for the movement and direction of movement

Returns

0 upon success, error code otherwise

Definition at line 112 of file file.h.

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seek() [2/2]

PropWare::ErrorCode PropWare::File::seek ( const int32_t  position )

inherited

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

[in]

position

Absolute position to move the file position indicator

Definition at line 147 of file file.h.

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tell()

int32_t PropWare::File::tell ( ) const

inherited

Obtain the value of the file position indicator.

Postcondition

The next byte to be read from the file

Definition at line 100 of file file.h.

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The documentation for this class was generated from the following file:

• PropWare/filesystem/fat/fatfilereader.h