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\ tag: deblocker support package
\
\ Copyright (C) 2003 Stefan Reinauer
\
\ See the file "COPYING" for further information about
\ the copyright and warranty status of this work.
\
" /packages" find-device
\ The deblocker package makes it easy to implement byte-oriented device
\ methods, using the block-oriented or record-oriented methods defined by
\ devices such as disks or tapes. It provides a layer of buffering between
\ the high-level byte-oriented interface and the low-level block-oriented
\ interface. deblocker uses the max-transfer, block-size, read-blocks and
\ write-blocks methods of its parent.
new-device
" deblocker" device-name
\ open ( -- flag )
\ Prepares the package for subsequent use, allocating the buffers used
\ by the deblocking process based upon the values returned by the parent
\ instance's max-transfer and block-size methods. Returns -1 if the
\ operation succeeds, 0 otherwise.
: open ( -- flag )
;
\ close ( -- )
\ Frees all resources that were allocated by open.
: close ( -- )
;
\ read ( adr len -- actual )
\ Reads at most len bytes from the device into the memory buffer
\ beginning at adr. Returns actual, the number of bytes actually
\ read, or 0 if the read operation failed. Uses the parent's read-
\ blocks method as necessary to satisfy the request, buffering any
\ unused bytes for the next request.
: read ( adr len -- actual )
;
\ Writes at most len bytes from the device into the memory buffer
\ beginning at adr. Returns actual, the number of bytes actually
\ read, or 0 if the write operation failed. Uses the parent's write-
\ blocks method as necessary to satisfy the request, buffering any
\ unused bytes for the next request.
: write ( adr len -- actual )
;
\ Sets the device position at which the next read or write will take
\ place. The position is specified by the 64-bit number x.position.
\ Returns 0 if the operation succeeds or -1 if it fails.
: seek ( x.position -- flag )
;
finish-device
\ clean up afterwards
device-end
|
