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TABLE OF CONTENTS
asyncio/CloseAsync
asyncio/OpenAsync
asyncio/ReadAsync
asyncio/ReadCharAsync
asyncio/SeekAsync
asyncio/WriteAsync
asyncio/WriteCharAsync
asyncio/CloseAsync asyncio/CloseAsync
NAME
CloseAsync -- close an async file.
SYNOPSIS
success = CloseAsync(file);
LONG CloseAsync(struct AsyncFile *);
FUNCTION
Closes a file, flushing any pending writes. Once this call has been
made, the file can no longer be accessed.
INPUTS
file - the file to close. May be NULL, in which case this function
returns -1 and sets the IoErr() code to ERROR_INVALID_LOCk.
RESULT
result - < 0 for an error, >= 0 for success. Indicates whether closing
the file worked or not. If the file was opened in read-mode,
then this call will always work. In case of error,
dos.library/IoErr() can give more information.
SEE ALSO
OpenAsync(), dos.library/Close()
asyncio/OpenAsync asyncio/OpenAsync
NAME
OpenAsync -- open a file for asynchronous IO.
SYNOPSIS
file = OpenAsync(fileName, accessMode, bufferSize);
struct AsyncFile OpenAsync(const STRPTR, UBYTE, LONG);
FUNCTION
The named file is opened and an async file handle returned. If the
accessMode is MODE_READ, an existing file is opened for reading.
If accessMode is MODE_WRITE, a new file is created for writing. If
a file of the same name already exists, it is first deleted. If
accessMode is MODE_APPEND, an existing file is prepared for writing.
Data written is added to the end of the file. If the file does not
exists, it is created.
'fileName' is a filename and CANNOT be a window specification such as
CON: or RAW:, or "*"
'bufferSize' specifies the size of the IO buffer to use. There are
in fact two buffers allocated, each of roughly (bufferSize/2) bytes
in size. The actual buffer size use can vary slightly as the size
is rounded to speed up DMA.
If the file cannot be opened for any reason, the value returned
will be NULL, and a secondary error code will be available by
calling the routine dos.library/IoErr().
INPUTS
name - name of the file to open, cannot be a window specification
accessMode - one of MODE_READ, MODE_WRITE, or MODE_APPEND
bufferSize - size of IO buffer to use. 8192 is recommended as it
provides very good performance for relatively little
memory.
RESULTS
file - an async file handle or NULL for failure. You should not access
the fields in the AsyncFile structure, these are private to the
async IO routines. In case of failure, dos.library/IoErr() can
give more information.
SEE ALSO
CloseAsync(), dos.library/Open()
asyncio/ReadAsync asyncio/ReadAsync
NAME
ReadAsync -- read bytes from an async file.
SYNOPSIS
actualLength = ReadAsync(file, buffer, numBytes);
LONG ReadAsync(struct AsyncFile *, APTR, LONG);
FUNCTION
This function reads bytes of information from an opened async file
into the buffer given. 'numBytes' is the number of bytes to read from
the file.
The value returned is the length of the information actually read.
So, when 'actualLength' is greater than zero, the value of
'actualLength' is the the number of characters read. Usually
ReadAsync() will try to fill up your buffer before returning. A value
of zero means that end-of-file has been reached. Errors are indicated
by a value of -1.
INPUTS
file - opened file to read, as obtained from OpenAsync()
buffer - buffer where to put bytes read
numBytes - number of bytes to read into buffer
RESULT
actualLength - actual number of bytes read, or -1 if an error. In
case of error, dos.library/IoErr() can give more
information.
SEE ALSO
OpenAsync(), CloseAsync(), ReadCharAsync(), WriteAsync(),
dos.library/Read()
asyncio/ReadCharAsync asyncio/ReadCharAsync
NAME
ReadCharAsync -- read a single byte from an async file.
SYNOPSIS
byte = ReadCharAsync(file);
LONG ReadCharAsync(struct AsyncFile *);
FUNCTION
This function reads a single byte from an async file. The byte is
returned, or -1 if there was an error reading, or if the end-of-file
was reached.
INPUTS
file - opened file to read from, as obtained from OpenAsync()
RESULT
byte - the byte read, or -1 if no byte was read. In case of error,
dos.library/IoErr() can give more information. If IoErr()
returns 0, it means end-of-file was reached. Any other value
indicates an error.
SEE ALSO
OpenAsync(), CloseAsync(), ReadAsync(), WriteCharAsync()
dos.library/Read()
asyncio/SeekAsync asyncio/SeekAsync
NAME
SeekAsync -- set the current position for reading or writing within
an async file.
SYNOPSIS
oldPosition = SeekAsync(file, position, mode);
LONG SeekAsync(struct AsyncFile *, LONG, BYTE);
FUNCTION
SeekAsync() sets the read/write cursor for the file 'file' to the
position 'position'. This position is used by the various read/write
functions as the place to start reading or writing. The result is the
current absolute position in the file, or -1 if an error occurs, in
which case dos.library/IoErr() can be used to find more information.
'mode' can be SEEK_START, SEEK_CURRENT or SEEK_END. It is used to
specify the relative start position. For example, 20 from current
is a position 20 bytes forward from current, -20 is 20 bytes back
from current.
To find out what the current position within a file is, simply seek
zero from current.
INPUTS
file - an opened async file, as obtained from OpenAsync()
position - the place where to move the read/write cursor
mode - the mode for the position, one of SEEK_START, SEEK_CURRENT,
or SEEK_END.
RESULT
oldPosition - the previous position of the read/write cursor, or -1
if an error occurs. In case of error, dos.library/IoErr()
can give more information.
SEE ALSO
OpenAsync(), CloseAsync(), ReadAsync(), WriteAsync(),
dos.library/Seek()
asyncio/WriteAsync asyncio/WriteAsync
NAME
WriteAsync -- write data to an async file.
SYNOPSIS
actualLength = WriteAsync(file, buffer, numBytes);
LONG WriteAsync(struct AsyncFile *, APTR, LONG);
FUNCTION
WriteAsync() writes bytes of data to an opened async file. 'numBytes'
indicates the number of bytes of data to be transferred. 'buffer'
points to the data to write. The value returned is the length of
information actually written. So, when 'numBytes' is greater than
zero, the value of 'numBytes' is the number of characters written.
Errors are indicated by a return value of -1.
INPUTS
file - an opened file, as obtained from OpenAsync()
buffer - address of data to write
numBytes - number of bytes to write to the file
RESULT
actualLength - number of bytes written, or -1 if error. In case
of error, dos.library/IoErr() can give more
information.
SEE ALSO
OpenAsync(), CloseAsync(), ReadAsync(), WriteCharAsync(),
dos.library/Write()
asyncio/WriteCharAsync asyncio/WriteCharAsync
NAME
WriteCharAsync -- write a single byte to an async file.
SYNOPSIS
result = WriteCharAsync(file, byte);
LONG WriteCharAsync(struct AsyncFile *, UBYTE);
FUNCTION
This function writes a single byte to an async file.
INPUTS
file - an opened async file, as obtained from OpenAsync()
byte - byte of data to add to the file
RESULT
result - 1 if the byte was written, -1 if there was an error. In
case of error, dos.library/IoErr() can give more information.
SEE ALSO
OpenAsync(), CloseAsync(), ReadAsync(), WriteAsync(),
dos.library/Write()