\ A less simple implementation of the blocks wordset.
\ Copyright (C) 1995,1996,1997,1998,2000,2003,2006 Free Software Foundation, Inc.
\ This file is part of Gforth.
\ Gforth is free software; you can redistribute it and/or
\ modify it under the terms of the GNU General Public License
\ as published by the Free Software Foundation; either version 2
\ of the License, or (at your option) any later version.
\ This program is distributed in the hope that it will be useful,
\ but WITHOUT ANY WARRANTY; without even the implied warranty of
\ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
\ GNU General Public License for more details.
\ You should have received a copy of the GNU General Public License
\ along with this program; if not, write to the Free Software
\ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
\ A more efficient implementation would use mmap on OSs that
\ provide it and many buffers on OSs that do not provide mmap.
\ Now, the replacement algorithm is "direct mapped"; change to LRU
\ if too slow. Using more buffers helps, too.
\ I think I avoid the assumption 1 char = 1 here, but I have not tested this
\ 1024 constant chars/block \ mandated by the standard
require struct.fs
struct
cell% field buffer-block \ the block number
cell% field buffer-fid \ the block's fid
cell% field buffer-dirty \ the block dirty flag
char% chars/block * field block-buffer \ the data
cell% 0 * field next-buffer
end-struct buffer-struct
Variable block-buffers
Variable last-block
$20 Value buffers
\ limit block files to 2GB; gforth <0.6.0 erases larger block files on
\ 32-bit systems
$200000 Value block-limit
User block-fid
User block-offset ( -- addr ) \ gforth
\G User variable containing the number of the first block (default
\G since 0.5.0: 0). Block files created with Gforth versions before
\G 0.5.0 have the offset 1. If you use these files you can: @code{1
\G offset !}; or add 1 to every block number used; or prepend 1024
\G characters to the file.
0 block-offset ! \ store 1 here fore 0.4.0 compatibility
' block-offset alias offset \ !! eliminate this?
: block-cold ( -- )
block-fid off last-block off
buffer-struct buffers * %alloc dup block-buffers ! ( addr )
buffer-struct %size buffers * erase ;
:noname ( -- )
defers 'cold
block-cold
; is 'cold
block-cold
Defer flush-blocks ( -- ) \ gforth
: open-blocks ( c-addr u -- ) \ gforth
\g Use the file, whose name is given by @i{c-addr u}, as the blocks file.
try ( c-addr u )
2dup open-fpath-file throw
rot close-file throw 2dup file-status throw bin open-file throw
>r 2drop r>
iferror ( c-addr u ior )
>r 2dup file-status nip 0= r> and throw \ does it really not exist?
r/w bin create-file throw
then endtry
block-fid @ IF
flush-blocks block-fid @ close-file throw
THEN
block-fid ! ;
: use ( "file" -- ) \ gforth
\g Use @i{file} as the blocks file.
name open-blocks ;
\ the file is opened as binary file, since it either will contain text
\ without newlines or binary data
: get-block-fid ( -- wfileid ) \ gforth
\G Return the file-id of the current blocks file. If no blocks
\G file has been opened, use @file{blocks.fb} as the default
\G blocks file.
block-fid @ 0=
if
s" blocks.fb" open-blocks
then
block-fid @ ;
: block-position ( u -- ) \ block
\G Position the block file to the start of block @i{u}.
dup block-limit u>= -35 and throw
offset @ - chars/block chars um* get-block-fid reposition-file throw ;
: update ( -- ) \ block
\G Mark the state of the current block buffer as assigned-dirty.
last-block @ ?dup IF buffer-dirty on THEN ;
: save-buffer ( buffer -- ) \ gforth
>r
r@ buffer-dirty @
if
r@ buffer-block @ block-position
r@ block-buffer chars/block r@ buffer-fid @ write-file throw
r@ buffer-fid @ flush-file throw
r@ buffer-dirty off
endif
rdrop ;
: empty-buffer ( buffer -- ) \ gforth
buffer-block off ;
: save-buffers ( -- ) \ block
\G Transfer the contents of each @code{update}d block buffer to
\G mass storage, then mark all block buffers as assigned-clean.
block-buffers @
buffers 0 ?DO dup save-buffer next-buffer LOOP drop ;
: empty-buffers ( -- ) \ block-ext
\G Mark all block buffers as unassigned; if any had been marked as
\G assigned-dirty (by @code{update}), the changes to those blocks
\G will be lost.
block-buffers @
buffers 0 ?DO dup empty-buffer next-buffer LOOP drop ;
: flush ( -- ) \ block
\G Perform the functions of @code{save-buffers} then
\G @code{empty-buffers}.
save-buffers
empty-buffers ;
' flush IS flush-blocks
: get-buffer ( u -- a-addr ) \ gforth
0 buffers um/mod drop buffer-struct %size * block-buffers @ + ;
: block ( u -- a-addr ) \ gforthman- block
\G If a block buffer is assigned for block @i{u}, return its
\G start address, @i{a-addr}. Otherwise, assign a block buffer
\G for block @i{u} (if the assigned block buffer has been
\G @code{update}d, transfer the contents to mass storage), read
\G the block into the block buffer and return its start address,
\G @i{a-addr}.
dup offset @ u< -35 and throw
dup get-buffer >r
dup r@ buffer-block @ <>
r@ buffer-fid @ block-fid @ <> or
if
r@ save-buffer
dup block-position
r@ block-buffer chars/block get-block-fid read-file throw
\ clear the rest of the buffer if the file is too short
r@ block-buffer over chars + chars/block rot chars - blank
r@ buffer-block !
get-block-fid r@ buffer-fid !
else
drop
then
r> dup last-block ! block-buffer ;
: buffer ( u -- a-addr ) \ block
\G If a block buffer is assigned for block @i{u}, return its
\G start address, @i{a-addr}. Otherwise, assign a block buffer
\G for block @i{u} (if the assigned block buffer has been
\G @code{update}d, transfer the contents to mass storage) and
\G return its start address, @i{a-addr}. The subtle difference
\G between @code{buffer} and @code{block} mean that you should
\G only use @code{buffer} if you don't care about the previous
\G contents of block @i{u}. In Gforth, this simply calls
\G @code{block}.
\ reading in the block is unnecessary, but simpler
block ;
User scr ( -- a-addr ) \ block-ext s-c-r
\G @code{User} variable -- @i{a-addr} is the address of a cell containing
\G the block number of the block most recently processed by
\G @code{list}.
0 scr !
\ nac31Mar1999 moved "scr @" to list to make the stack comment correct
: updated? ( n -- f ) \ gforth
\G Return true if @code{updated} has been used to mark block @i{n}
\G as assigned-dirty.
buffer
[ 0 buffer-dirty 0 block-buffer - ] Literal + @ ;
: list ( u -- ) \ block-ext
\G Display block @i{u}. In Gforth, the block is displayed as 16
\G numbered lines, each of 64 characters.
\ calling block again and again looks inefficient but is necessary
\ in a multitasking environment
dup scr !
." Screen " u.
scr @ updated? 0= IF ." not " THEN ." modified " cr
16 0
?do
i 2 .r space scr @ block i 64 * chars + 64 type cr
loop ;
[IFDEF] current-input
:noname 2 <> -12 and throw >in ! blk ! ;
\ restore-input
:noname blk @ >in @ 2 ; \ save-input
:noname 2 ; \ source-id "*a block*"
:noname 1 blk +! 1 loadline +! >in off true ; \ refill
:noname blk @ block chars/block ; \ source
Create block-input A, A, A, A, A,
: load ( i*x n -- j*x ) \ block
\G Save the current input source specification. Store @i{n} in
\G @code{BLK}, set @code{>IN} to 0 and interpret. When the parse
\G area is exhausted, restore the input source specification.
block-input 0 new-tib dup loadline ! blk ! s" * a block*" loadfilename 2!
['] interpret catch pop-file throw ;
[ELSE]
: (source) ( -- c-addr u )
blk @ ?dup
IF block chars/block
ELSE tib #tib @
THEN ;
' (source) IS source ( -- c-addr u ) \ core
\G @i{c-addr} is the address of the input buffer and @i{u} is the
\G number of characters in it.
: load ( i*x n -- j*x ) \ block
\G Save the current input source specification. Store @i{n} in
\G @code{BLK}, set @code{>IN} to 0 and interpret. When the parse
\G area is exhausted, restore the input source specification.
s" * a block*" loadfilename>r
push-file
dup loadline ! blk ! >in off ['] interpret catch
pop-file
r>loadfilename
throw ;
[THEN]
: thru ( i*x n1 n2 -- j*x ) \ block-ext
\G @code{load} the blocks @i{n1} through @i{n2} in sequence.
1+ swap ?DO I load LOOP ;
: +load ( i*x n -- j*x ) \ gforth
\G Used within a block to load the block specified as the
\G current block + @i{n}.
blk @ + load ;
: +thru ( i*x n1 n2 -- j*x ) \ gforth
\G Used within a block to load the range of blocks specified as the
\G current block + @i{n1} thru the current block + @i{n2}.
1+ swap ?DO I +load LOOP ;
: --> ( -- ) \ gforthman- gforth chain
\G If this symbol is encountered whilst loading block @i{n},
\G discard the remainder of the block and load block @i{n+1}. Used
\G for chaining multiple blocks together as a single loadable
\G unit. Not recommended, because it destroys the independence of
\G loading. Use @code{thru} (which is standard) or @code{+thru}
\G instead.
refill drop ; immediate
: block-included ( a-addr u -- ) \ gforth
\G Use within a block that is to be processed by @code{load}. Save
\G the current blocks file specification, open the blocks file
\G specified by @i{a-addr u} and @code{load} block 1 from that
\G file (which may in turn chain or load other blocks). Finally,
\G close the blocks file and restore the original blocks file.
block-fid @ >r block-fid off open-blocks
1 load block-fid @ close-file throw flush
r> block-fid ! ;
\ thrown out because it may provide unpleasant surprises - anton
\ : include ( "name" -- )
\ name 2dup dup 3 - /string s" .fb" compare
\ 0= IF block-included ELSE included THEN ;
get-current environment-wordlist set-current
true constant block
true constant block-ext
set-current
: bye ( -- ) \ tools-ext
\G Return control to the host operating system (if any).
['] flush catch drop bye ;
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