Annotation of gforth/blocks.fs, revision 1.25
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
1.1 anton 48:
1.17 anton 49: : block-cold ( -- )
1.16 jwilke 50: block-fid off last-block off
1.17 anton 51: buffer-struct buffers * %alloc dup block-buffers ! ( addr )
52: buffer-struct %size buffers * erase ;
1.1 anton 53:
1.16 jwilke 54: ' block-cold INIT8 chained
1.5 pazsan 55:
56: block-cold
57:
1.24 crook 58: Defer flush-blocks ( -- ) \ gforth
1.5 pazsan 59:
1.24 crook 60: : open-blocks ( c-addr u -- ) \ gforth
61: \g Use the file, whose name is given by @i{c-addr u}, as the blocks file.
1.18 pazsan 62: 2dup open-fpath-file 0<>
1.5 pazsan 63: if
1.18 pazsan 64: r/w bin create-file throw
1.5 pazsan 65: else
1.8 pazsan 66: rot close-file throw 2dup file-status throw bin open-file throw
67: >r 2drop r>
1.5 pazsan 68: then
1.12 anton 69: block-fid @ IF flush-blocks block-fid @ close-file throw THEN
1.5 pazsan 70: block-fid ! ;
1.8 pazsan 71:
1.10 anton 72: : use ( "file" -- ) \ gforth
1.24 crook 73: \g Use @i{file} as the blocks file.
1.11 anton 74: name open-blocks ;
1.1 anton 75:
1.3 anton 76: \ the file is opened as binary file, since it either will contain text
77: \ without newlines or binary data
1.24 crook 78: : get-block-fid ( -- wfileid ) \ gforth
79: \G Return the file-id of the current blocks file. If no blocks
80: \G file has been opened, use @file{blocks.fb} as the default
81: \G blocks file.
1.1 anton 82: block-fid @ 0=
83: if
1.11 anton 84: s" blocks.fb" open-blocks
1.1 anton 85: then
86: block-fid @ ;
87:
1.20 pazsan 88: : block-position ( u -- ) \ block
1.24 crook 89: \G Position the block file to the start of block @i{u}.
1.3 anton 90: 1- chars/block chars um* get-block-fid reposition-file throw ;
1.1 anton 91:
1.20 pazsan 92: : update ( -- ) \ block
1.24 crook 93: \G Mark the current block buffer as dirty.
1.5 pazsan 94: last-block @ ?dup IF buffer-dirty on THEN ;
1.1 anton 95:
1.20 pazsan 96: : save-buffer ( buffer -- ) \ gforth
97: >r
1.5 pazsan 98: r@ buffer-dirty @ r@ buffer-block @ 0<> and
1.1 anton 99: if
1.5 pazsan 100: r@ buffer-block @ block-position
101: r@ block-buffer chars/block r@ buffer-fid @ write-file throw
102: r@ buffer-dirty off
103: endif
104: rdrop ;
105:
1.20 pazsan 106: : empty-buffer ( buffer -- ) \ gforth
1.5 pazsan 107: buffer-block off ;
108:
1.20 pazsan 109: : save-buffers ( -- ) \ block
1.24 crook 110: \G Transfer the contents of each @code{update}d block buffer to
111: \G mass storage, then mark all block buffers as unassigned.
1.20 pazsan 112: block-buffers @
1.24 crook 113: buffers 0 ?DO dup save-buffer next-buffer LOOP drop ;
1.1 anton 114:
1.24 crook 115: : empty-buffers ( -- ) \ block-ext
116: \G Mark all block buffers as unassigned; if any had been marked as
117: \G assigned-dirty (by @code{update}), the changes to those blocks
118: \G will be lost.
1.20 pazsan 119: block-buffers @
1.24 crook 120: buffers 0 ?DO dup empty-buffer next-buffer LOOP drop ;
1.1 anton 121:
1.20 pazsan 122: : flush ( -- ) \ block
1.24 crook 123: \G Perform the functions of @code{save-buffers} then
124: \G @code{empty-buffers}.
1.1 anton 125: save-buffers
126: empty-buffers ;
127:
1.12 anton 128: ' flush IS flush-blocks
1.5 pazsan 129:
1.20 pazsan 130: : get-buffer ( n -- a-addr ) \ gforth
1.17 anton 131: buffers mod buffer-struct %size * block-buffers @ + ;
1.5 pazsan 132:
1.21 crook 133: : block ( u -- a-addr ) \ block- block
1.24 crook 134: \G If a block buffer is assigned for block @i{u}, return its
135: \G start address, @i{a-addr}. Otherwise, assign a block buffer
136: \G for block @i{u} (if the assigned block buffer has been
137: \G @code{update}d, transfer the contents to mass storage), read
138: \G the block into the block buffer and return its start address,
139: \G @i{a-addr}.
1.1 anton 140: dup 0= -35 and throw
1.5 pazsan 141: dup get-buffer >r
142: dup r@ buffer-block @ <>
1.9 pazsan 143: r@ buffer-fid @ block-fid @ <> or
1.1 anton 144: if
1.5 pazsan 145: r@ save-buffer
1.1 anton 146: dup block-position
1.5 pazsan 147: r@ block-buffer chars/block get-block-fid read-file throw
1.1 anton 148: \ clear the rest of the buffer if the file is too short
1.5 pazsan 149: r@ block-buffer over chars + chars/block rot chars - blank
150: r@ buffer-block !
151: get-block-fid r@ buffer-fid !
1.1 anton 152: else
153: drop
154: then
1.5 pazsan 155: r> dup last-block ! block-buffer ;
1.1 anton 156:
1.20 pazsan 157: : buffer ( u -- a-addr ) \ block
1.24 crook 158: \G If a block buffer is assigned for block @i{u}, return its
159: \G start address, @i{a-addr}. Otherwise, assign a block buffer
160: \G for block @i{u} (if the assigned block buffer has been
161: \G @code{update}d, transfer the contents to mass storage) and
162: \G return its start address, @i{a-addr}. The subtle difference
163: \G between @code{buffer} and @code{block} mean that you should
164: \G only use @code{buffer} if you don't care about the previous
165: \G contents of block @i{u}. In Gforth, this simply calls
166: \G @code{block}.
1.1 anton 167: \ reading in the block is unnecessary, but simpler
168: block ;
169:
1.21 crook 170: User scr ( -- a-addr ) \ block-ext
1.24 crook 171: \G USER VARIABLE: @i{a-addr} is the address of a cell containing
1.21 crook 172: \G the block number of the block most recently processed by
1.24 crook 173: \G @code{list}.
174: 0 scr !
1.1 anton 175:
1.24 crook 176: \ nac31Mar1999 moved "scr @" to list to make the stack comment correct
1.20 pazsan 177: : updated? ( n -- f ) \ gforth
1.24 crook 178: \G Return true if block @i{n} has been marked as dirty.
179: buffer
1.5 pazsan 180: [ 0 buffer-dirty 0 block-buffer - ] Literal + @ ;
181:
1.24 crook 182: : list ( u -- ) \ block-ext
183: \G Display block @i{u}. In Gforth, the block is displayed as 16
184: \G numbered lines, each of 64 characters.
1.1 anton 185: \ calling block again and again looks inefficient but is necessary
186: \ in a multitasking environment
187: dup scr !
1.5 pazsan 188: ." Screen " u.
1.24 crook 189: scr @ updated? 0= IF ." not " THEN ." modified " cr
1.1 anton 190: 16 0
191: ?do
1.4 anton 192: i 2 .r space scr @ block i 64 * chars + 64 type cr
1.1 anton 193: loop ;
194:
1.23 crook 195: : (source) ( -- c-addr u )
1.2 pazsan 196: blk @ ?dup
197: IF block chars/block
198: ELSE tib #tib @
199: THEN ;
200:
1.23 crook 201: ' (source) IS source ( -- c-addr u ) \ core
1.24 crook 202: \G @i{c-addr} is the address of the input buffer and @i{u} is the
1.23 crook 203: \G number of characters in it.
1.2 pazsan 204:
1.20 pazsan 205: : load ( i*x n -- j*x ) \ block
1.24 crook 206: \G Save the current input source specification. Store @i{n} in
207: \G @code{BLK}, set @code{>IN} to 0 and interpret. When the parse
208: \G area is exhausted, restore the input source specification.
209: push-file
210: dup loadline ! blk ! >in off ['] interpret catch
211: pop-file throw ;
212:
213: : thru ( i*x n1 n2 -- j*x ) \ block-ext
214: \G @code{load} the blocks @i{n1} through @i{n2} in sequence.
215: 1+ swap ?DO I load LOOP ;
216:
217: : +load ( i*x n -- j*x ) \ gforth
218: \G Used within a block to load the block specified as the
219: \G current block + @i{n}.
1.20 pazsan 220: blk @ + load ;
1.2 pazsan 221:
1.24 crook 222: : +thru ( i*x n1 n2 -- j*x ) \ gforth
223: \G Used within a block to load the range of blocks specified as the
224: \G current block + @i{n1} thru the current block + @i{n2}.
225: 1+ swap ?DO I +load LOOP ;
226:
1.25 ! anton 227: : --> ( -- ) \ gforth- gforth chain
1.24 crook 228: \G If this symbol is encountered whilst loading block @i{n},
229: \G discard the remainder of the block and load block @i{n+1}. Used
1.25 ! anton 230: \G for chaining multiple blocks together as a single loadable
! 231: \G unit. Not recommended, because it destroys the independence of
! 232: \G loading. Use @code{thru} (which is standard) or @code{+thru}
! 233: \G instead.
1.20 pazsan 234: refill drop ; immediate
1.5 pazsan 235:
1.24 crook 236: : block-included ( a-addr u -- ) \ gforth
237: \G Use within a block that is to be processed by @code{load}. Save
238: \G the current blocks file specification, open the blocks file
239: \G specified by @i{a-addr u} and @code{load} block 1 from that
240: \G file (which may in turn chain or load other blocks). Finally,
241: \G close the blocks file and restore the original blocks file.
1.11 anton 242: block-fid @ >r block-fid off open-blocks
1.5 pazsan 243: 1 load block-fid @ close-file throw flush
244: r> block-fid ! ;
245:
1.13 anton 246: \ thrown out because it may provide unpleasant surprises - anton
247: \ : include ( "name" -- )
248: \ name 2dup dup 3 - /string s" .fb" compare
249: \ 0= IF block-included ELSE included THEN ;
1.5 pazsan 250:
1.4 anton 251: get-current environment-wordlist set-current
252: true constant block
253: true constant block-ext
254: set-current
1.5 pazsan 255:
1.21 crook 256: : bye ( -- ) \ tools-ext
257: \G Return control to the host operating system (if any).
258: ['] flush catch drop bye ;
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