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Autodocs
 Libraries:
 iffparse.library
  AllocIFF
  AllocLocalItem
  CloseClipboard
  CloseIFF
  CollectionChunk
  CollectionChunks
  CurrentChunk
  EntryHandler
  ExitHandler
  FindCollection
  FindLocalItem
  FindProp
  FindPropContext
  FreeIFF
  FreeLocalItem
  GoodID
  GoodType
  IDtoStr
  InitIFF
  InitIFFasClip
  InitIFFasDOS
  LocalItemData
  OpenClipboard
  OpenIFF
  ParentChunk
  ParseIFF
  PopChunk
  PropChunk
  PropChunks
  PushChunk
  ReadChunkBytes
  ReadChunkRecords
  SetLocalItemPurge
  StopChunk
  StopChunks
  StopOnExit
  StoreItemInContext
  StoreLocalItem
  WriteChunkBytes
  WriteChunkRecords
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GuruMeditation
Docs » Autodocs » iffparse.library » InitIFF

NAME

	InitIFF -- initialize an IFFHandle structure as a user stream. (V36)

SYNOPSIS

	InitIFF(iff, flags, streamHook);
A0 D0 A1
VOID InitIFF(struct IFFHandle *, LONG, struct Hook *);

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 structure.
A1: pointer to IFFStreamCmd structure.
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.
streamHook - pointer to Hook structure.

SEE ALSO

<utility/hooks.h>, <libraries/iffparse.h>

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