Buffer Class

A Buffer is a useful class for the communications functions. It can be made to wrap up an existing String or Binary item and is typically used for sending or receiving data over a communications channel.

Buffer Creation

The following creates a Buffer with a space for 128 bytes:

    (create Buffer 128)

To create a buffer of the same size as a Binary or String object, and containing the same data:

    (create Buffer "Hello there!")

    (create Buffer 0x"0102030005")

Buffer Properties

None

Buffer Methods

method name	description
`length`	return the length of the buffered data
`bufferLength`	return the length of the buffer -- ie. the maximum length of data which can be held
`string`	convert the buffered data to a string -- note that strings are terminated by a null (hex value `00`) character
`binary`	convert the buffered data to a binary
`fromFile`	fill the buffer with data from the contents of the supplied file
`extract`	extract a range of bytes from the binary data and return them
`append`	append the supplied bytes to the end of the buffered data
`prepend`	prepend the supplied bytes at the start of the buffered data
`reset`	reset the buffer, removing any stored data but keeping the buffer size unchanged
`consume`	consume the supplied number of bytes from the beginning of the buffered data
`==`	test equality of buffers
`!=`	test inequality of buffers

`length`

Return the length of the buffered data.

Arguments: none

Return type: Integer

`bufferLength`

Return the length of the buffer -- ie. the maximum length of data which can be held within the buffer.

Arguments: none

Return type: Integer

`string`

Convert the buffered data to a string -- note that strings are terminated by a null (hex value 00) character.

Arguments: none

Return type: String

`binary`

Convert the buffered data to a binary .

Arguments: none

Return type: Binary

`fromFile`

Fill the buffer with data from the contents of the supplied file. This surgically alters the buffer.

Arguments:

filename String

Return type: the empty List ()

`extract`

Extract a range of bytes from the buffered data and return them. This is similar to the substring method for a String.

Arguments:

start	`Integer`
length (optional)	`Integer`

Return type: Binary

`append`

Append the supplied bytes to the end of the buffered data. This surgically alters the buffer.

Arguments:

data	`String` or `Binary`

Return type: the empty List () is returned.

`prepend`

Prepend the supplied bytes to the start of the buffered data. This surgically alters the buffer.

Arguments:

data	`String` or `Binary`

Return type: the empty List () is returned.

`reset`

Reset the buffer, removing any stored data but keeping the buffer size unchanged.

Arguments: none

Return type: the empty List () is returned.

`consume`

Consume the supplied number of bytes from the beginning of the buffered data.

Arguments:

nBytes Integer

Return type: the empty List () is returned.

`==`

Test equality of buffers. If the items are the same, the Symbol true is returned, otherwise the empty List () is returned.

Arguments:

item Binary

Return type: Symbol true or the empty List ()

`!=`

Test in-equality of buffers. If the items are the different, the Symbol true is returned, otherwise the empty List () is returned.

Arguments:

item Binary

Return type: Symbol true or the empty List ()

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