NAME
    InitIFF -- Initialize an IFFHandle struct as a user stream.

SYNOPSIS
    InitIFF (iff, flags, streamhook)
             a0    d0        a1

    struct IFFHandle *iff;
    LONG             flags;
    struct Hook     *streamhook;

FUNCTION
    Initializes an IFFHandle as a general user-defined stream by
    allowing the user to declare a hook that the library will call to
    accomplish the low-level reading, writing, and seeking of the stream.
    Flags are the stream I/O flags for the specified stream; typically a
    combination of the IFFF_?SEEK flags.

    The stream vector is called with the following arguments:

            A0:     pointer to streamhook.
            A2:     pointer to IFFHandle struct.
            A1:     pointer to IFFStreamCmd struct.

    The IFFStreamCmd packet appears as follows:

            sc_Command:     Contains an IFFCMD_#? value
            sc_Buf:         Pointer to memory buffer
            sc_NBytes:      Number of bytes involved in operation

    The values taken on by sc_Command, and their meaning, are as follows:

    IFFCMD_INIT:
            Prepare your stream for reading.  This is used for certain
            streams that can't be read immediately upon opening, and need
            further preparation.  (The clipboard.device is an example of
            such a stream.)  This operation is allowed to fail;  any
            error code will be returned directly to the client.  sc_Buf
            and sc_NBytes have no meaning here.
    IFFCMD_CLEANUP:
            Terminate the transaction with the associated stream.  This
            is used with streams that can't simply be closed.  (Again,
            the clipboard is an example of such a stream.)  This
            operation is not permitted to fail;  any error returned will
            be ignored (best to return 0, though).  sc_Buf and sc_NBytes
            have no meaning here.
    IFFCMD_READ:
            Read from the stream.  You are to read sc_NBytes from the
            stream and place them in the buffer pointed to by sc_Buf.
            Any (non-zero) error returned will be remapped by the parser
            into IFFERR_READ.
    IFFCMD_WRITE:
            Write to the stream.  You are to write sc_NBytes to the
            stream from the buffer pointed to by sc_Buf.  Any (non-zero)
            error returned will be remapped by the parser into
            IFFERR_WRITE.
    IFFCMD_SEEK:
            Seek on the stream.  You are to perform a seek on the stream
            relative to the current position.  sc_NBytes is signed;
            negative values mean seek backward, positive values mean seek
            forward.  sc_Buf has no meaning here.  Any (non-zero) error
            returned will be remapped by the parser into IFFERR_SEEK.

    All errors are returned in D0.  A return of 0 indicates success.
    UNDER NO CIRCUMSTANCES are you permitted to write to the IFFStreamCmd
    structure.

INPUTS
    iff     - pointer to IFFHandle structure to initialize.
    flags   - stream I/O flags for the IFFHandle.
    hook    - pointer to Hook structure.

RESULT

EXAMPLE

NOTES

BUGS

SEE ALSO
    utility/hooks.h

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