Multi Select Parameter From Function - Select All?

I am using RS 2000. I have a multi select parameter where I can select multiple states by separating with a comma. I am trying to figure out how to incorporate an "All" parameter.

Query:

Select [name], city, state, zipcode
From Golf inner join charlist_to_table(@State,Default)f on State = f.str

Function:

CREATE FUNCTION charlist_to_table
(@list ntext,
@delimiter nchar(1) = N',')
RETURNS @tbl Table (listpos int IDENTITY(1, 1) NOT NULL,
str varchar(4000),
nstr nvarchar(2000)) AS
BEGIN
DECLARE @pos int,
@textpos int,
@chunklen smallint,
@tmpstr nvarchar(4000),
@leftover nvarchar(4000),
@tmpval nvarchar(4000)
SET @textpos = 1
SET @leftover = ''
WHILE @textpos <= datalength(@list) / 2
BEGIN
SET @chunklen = 4000 - datalength(@leftover) / 2
SET @tmpstr = @leftover + substring(@list, @textpos, @chunklen)
SET @textpos = @textpos + @chunklen
SET @pos = charindex(@delimiter, @tmpstr)
WHILE @pos > 0
BEGIN
SET @tmpval = ltrim(rtrim(left(@tmpstr, @pos - 1)))
INSERT @tbl (str, nstr) VALUES(@tmpval, @tmpval)
SET @tmpstr = substring(@tmpstr, @pos + 1, len(@tmpstr))
SET @pos = charindex(@delimiter, @tmpstr)
END
SET @leftover = @tmpstr
END
INSERT @tbl(str, nstr) VALUES (ltrim(rtrim(@leftover)),
ltrim(rtrim(@leftover)))
RETURN
END
GO


Anyone have any ideas?

Thanks,
Deb