Annotation of gforth/blocks.fs, revision 1.26
1.5 pazsan 1: \ A less simple implementation of the blocks wordset.
1.1 anton 2:
1.19 anton 3: \ Copyright (C) 1995,1996,1997,1998 Free Software Foundation, Inc.
1.7 anton 4:
5: \ This file is part of Gforth.
6:
7: \ Gforth is free software; you can redistribute it and/or
8: \ modify it under the terms of the GNU General Public License
9: \ as published by the Free Software Foundation; either version 2
10: \ of the License, or (at your option) any later version.
11:
12: \ This program is distributed in the hope that it will be useful,
13: \ but WITHOUT ANY WARRANTY; without even the implied warranty of
14: \ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15: \ GNU General Public License for more details.
16:
17: \ You should have received a copy of the GNU General Public License
18: \ along with this program; if not, write to the Free Software
19: \ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20:
21:
22: \ A more efficient implementation would use mmap on OSs that
1.1 anton 23: \ provide it and many buffers on OSs that do not provide mmap.
24:
1.5 pazsan 25: \ Now, the replacement algorithm is "direct mapped"; change to LRU
26: \ if too slow. Using more buffers helps, too.
27:
1.1 anton 28: \ I think I avoid the assumption 1 char = 1 here, but I have not tested this
29:
1.2 pazsan 30: \ 1024 constant chars/block \ mandated by the standard
1.1 anton 31:
1.5 pazsan 32: require struct.fs
33:
34: struct
1.17 anton 35: cell% field buffer-block \ the block number
36: cell% field buffer-fid \ the block's fid
37: cell% field buffer-dirty \ the block dirty flag
38: char% chars/block * field block-buffer \ the data
39: cell% 0 * field next-buffer
1.5 pazsan 40: end-struct buffer-struct
41:
42: Variable block-buffers
43: Variable last-block
44:
45: $20 Value buffers
46:
47: User block-fid
1.26 ! pazsan 48: User offset 0 offset ! \ store 1 here fore 0.4.0 compatibility
1.1 anton 49:
1.17 anton 50: : block-cold ( -- )
1.16 jwilke 51: block-fid off last-block off
1.17 anton 52: buffer-struct buffers * %alloc dup block-buffers ! ( addr )
53: buffer-struct %size buffers * erase ;
1.1 anton 54:
1.16 jwilke 55: ' block-cold INIT8 chained
1.5 pazsan 56:
57: block-cold
58:
1.24 crook 59: Defer flush-blocks ( -- ) \ gforth
1.5 pazsan 60:
1.24 crook 61: : open-blocks ( c-addr u -- ) \ gforth
62: \g Use the file, whose name is given by @i{c-addr u}, as the blocks file.
1.18 pazsan 63: 2dup open-fpath-file 0<>
1.5 pazsan 64: if
1.18 pazsan 65: r/w bin create-file throw
1.5 pazsan 66: else
1.8 pazsan 67: rot close-file throw 2dup file-status throw bin open-file throw
68: >r 2drop r>
1.5 pazsan 69: then
1.12 anton 70: block-fid @ IF flush-blocks block-fid @ close-file throw THEN
1.5 pazsan 71: block-fid ! ;
1.8 pazsan 72:
1.10 anton 73: : use ( "file" -- ) \ gforth
1.24 crook 74: \g Use @i{file} as the blocks file.
1.11 anton 75: name open-blocks ;
1.1 anton 76:
1.3 anton 77: \ the file is opened as binary file, since it either will contain text
78: \ without newlines or binary data
1.24 crook 79: : get-block-fid ( -- wfileid ) \ gforth
80: \G Return the file-id of the current blocks file. If no blocks
81: \G file has been opened, use @file{blocks.fb} as the default
82: \G blocks file.
1.1 anton 83: block-fid @ 0=
84: if
1.11 anton 85: s" blocks.fb" open-blocks
1.1 anton 86: then
87: block-fid @ ;
88:
1.20 pazsan 89: : block-position ( u -- ) \ block
1.24 crook 90: \G Position the block file to the start of block @i{u}.
1.26 ! pazsan 91: offset @ - chars/block chars um* get-block-fid reposition-file throw ;
1.1 anton 92:
1.20 pazsan 93: : update ( -- ) \ block
1.24 crook 94: \G Mark the current block buffer as dirty.
1.5 pazsan 95: last-block @ ?dup IF buffer-dirty on THEN ;
1.1 anton 96:
1.20 pazsan 97: : save-buffer ( buffer -- ) \ gforth
98: >r
1.5 pazsan 99: r@ buffer-dirty @ r@ buffer-block @ 0<> and
1.1 anton 100: if
1.5 pazsan 101: r@ buffer-block @ block-position
102: r@ block-buffer chars/block r@ buffer-fid @ write-file throw
103: r@ buffer-dirty off
104: endif
105: rdrop ;
106:
1.20 pazsan 107: : empty-buffer ( buffer -- ) \ gforth
1.5 pazsan 108: buffer-block off ;
109:
1.20 pazsan 110: : save-buffers ( -- ) \ block
1.24 crook 111: \G Transfer the contents of each @code{update}d block buffer to
112: \G mass storage, then mark all block buffers as unassigned.
1.20 pazsan 113: block-buffers @
1.24 crook 114: buffers 0 ?DO dup save-buffer next-buffer LOOP drop ;
1.1 anton 115:
1.24 crook 116: : empty-buffers ( -- ) \ block-ext
117: \G Mark all block buffers as unassigned; if any had been marked as
118: \G assigned-dirty (by @code{update}), the changes to those blocks
119: \G will be lost.
1.20 pazsan 120: block-buffers @
1.24 crook 121: buffers 0 ?DO dup empty-buffer next-buffer LOOP drop ;
1.1 anton 122:
1.20 pazsan 123: : flush ( -- ) \ block
1.24 crook 124: \G Perform the functions of @code{save-buffers} then
125: \G @code{empty-buffers}.
1.1 anton 126: save-buffers
127: empty-buffers ;
128:
1.12 anton 129: ' flush IS flush-blocks
1.5 pazsan 130:
1.26 ! pazsan 131: : get-buffer ( u -- a-addr ) \ gforth
! 132: 0 buffers um/mod drop buffer-struct %size * block-buffers @ + ;
1.5 pazsan 133:
1.21 crook 134: : block ( u -- a-addr ) \ block- block
1.24 crook 135: \G If a block buffer is assigned for block @i{u}, return its
136: \G start address, @i{a-addr}. Otherwise, assign a block buffer
137: \G for block @i{u} (if the assigned block buffer has been
138: \G @code{update}d, transfer the contents to mass storage), read
139: \G the block into the block buffer and return its start address,
140: \G @i{a-addr}.
1.26 ! pazsan 141: dup offset @ u< -35 and throw
1.5 pazsan 142: dup get-buffer >r
143: dup r@ buffer-block @ <>
1.9 pazsan 144: r@ buffer-fid @ block-fid @ <> or
1.1 anton 145: if
1.5 pazsan 146: r@ save-buffer
1.1 anton 147: dup block-position
1.5 pazsan 148: r@ block-buffer chars/block get-block-fid read-file throw
1.1 anton 149: \ clear the rest of the buffer if the file is too short
1.5 pazsan 150: r@ block-buffer over chars + chars/block rot chars - blank
151: r@ buffer-block !
152: get-block-fid r@ buffer-fid !
1.1 anton 153: else
154: drop
155: then
1.5 pazsan 156: r> dup last-block ! block-buffer ;
1.1 anton 157:
1.20 pazsan 158: : buffer ( u -- a-addr ) \ block
1.24 crook 159: \G If a block buffer is assigned for block @i{u}, return its
160: \G start address, @i{a-addr}. Otherwise, assign a block buffer
161: \G for block @i{u} (if the assigned block buffer has been
162: \G @code{update}d, transfer the contents to mass storage) and
163: \G return its start address, @i{a-addr}. The subtle difference
164: \G between @code{buffer} and @code{block} mean that you should
165: \G only use @code{buffer} if you don't care about the previous
166: \G contents of block @i{u}. In Gforth, this simply calls
167: \G @code{block}.
1.1 anton 168: \ reading in the block is unnecessary, but simpler
169: block ;
170:
1.21 crook 171: User scr ( -- a-addr ) \ block-ext
1.24 crook 172: \G USER VARIABLE: @i{a-addr} is the address of a cell containing
1.21 crook 173: \G the block number of the block most recently processed by
1.24 crook 174: \G @code{list}.
175: 0 scr !
1.1 anton 176:
1.24 crook 177: \ nac31Mar1999 moved "scr @" to list to make the stack comment correct
1.20 pazsan 178: : updated? ( n -- f ) \ gforth
1.24 crook 179: \G Return true if block @i{n} has been marked as dirty.
180: buffer
1.5 pazsan 181: [ 0 buffer-dirty 0 block-buffer - ] Literal + @ ;
182:
1.24 crook 183: : list ( u -- ) \ block-ext
184: \G Display block @i{u}. In Gforth, the block is displayed as 16
185: \G numbered lines, each of 64 characters.
1.1 anton 186: \ calling block again and again looks inefficient but is necessary
187: \ in a multitasking environment
188: dup scr !
1.5 pazsan 189: ." Screen " u.
1.24 crook 190: scr @ updated? 0= IF ." not " THEN ." modified " cr
1.1 anton 191: 16 0
192: ?do
1.4 anton 193: i 2 .r space scr @ block i 64 * chars + 64 type cr
1.1 anton 194: loop ;
195:
1.23 crook 196: : (source) ( -- c-addr u )
1.2 pazsan 197: blk @ ?dup
198: IF block chars/block
199: ELSE tib #tib @
200: THEN ;
201:
1.23 crook 202: ' (source) IS source ( -- c-addr u ) \ core
1.24 crook 203: \G @i{c-addr} is the address of the input buffer and @i{u} is the
1.23 crook 204: \G number of characters in it.
1.2 pazsan 205:
1.20 pazsan 206: : load ( i*x n -- j*x ) \ block
1.24 crook 207: \G Save the current input source specification. Store @i{n} in
208: \G @code{BLK}, set @code{>IN} to 0 and interpret. When the parse
209: \G area is exhausted, restore the input source specification.
210: push-file
211: dup loadline ! blk ! >in off ['] interpret catch
212: pop-file throw ;
213:
214: : thru ( i*x n1 n2 -- j*x ) \ block-ext
215: \G @code{load} the blocks @i{n1} through @i{n2} in sequence.
216: 1+ swap ?DO I load LOOP ;
217:
218: : +load ( i*x n -- j*x ) \ gforth
219: \G Used within a block to load the block specified as the
220: \G current block + @i{n}.
1.20 pazsan 221: blk @ + load ;
1.2 pazsan 222:
1.24 crook 223: : +thru ( i*x n1 n2 -- j*x ) \ gforth
224: \G Used within a block to load the range of blocks specified as the
225: \G current block + @i{n1} thru the current block + @i{n2}.
226: 1+ swap ?DO I +load LOOP ;
227:
1.25 anton 228: : --> ( -- ) \ gforth- gforth chain
1.24 crook 229: \G If this symbol is encountered whilst loading block @i{n},
230: \G discard the remainder of the block and load block @i{n+1}. Used
1.25 anton 231: \G for chaining multiple blocks together as a single loadable
232: \G unit. Not recommended, because it destroys the independence of
233: \G loading. Use @code{thru} (which is standard) or @code{+thru}
234: \G instead.
1.20 pazsan 235: refill drop ; immediate
1.5 pazsan 236:
1.24 crook 237: : block-included ( a-addr u -- ) \ gforth
238: \G Use within a block that is to be processed by @code{load}. Save
239: \G the current blocks file specification, open the blocks file
240: \G specified by @i{a-addr u} and @code{load} block 1 from that
241: \G file (which may in turn chain or load other blocks). Finally,
242: \G close the blocks file and restore the original blocks file.
1.11 anton 243: block-fid @ >r block-fid off open-blocks
1.5 pazsan 244: 1 load block-fid @ close-file throw flush
245: r> block-fid ! ;
246:
1.13 anton 247: \ thrown out because it may provide unpleasant surprises - anton
248: \ : include ( "name" -- )
249: \ name 2dup dup 3 - /string s" .fb" compare
250: \ 0= IF block-included ELSE included THEN ;
1.5 pazsan 251:
1.4 anton 252: get-current environment-wordlist set-current
253: true constant block
254: true constant block-ext
255: set-current
1.5 pazsan 256:
1.21 crook 257: : bye ( -- ) \ tools-ext
258: \G Return control to the host operating system (if any).
259: ['] flush catch drop bye ;
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