1: \ A less simple implementation of the blocks wordset.
2:
3: \ Copyright (C) 1995 Free Software Foundation, Inc.
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
23: \ provide it and many buffers on OSs that do not provide mmap.
24:
25: \ Now, the replacement algorithm is "direct mapped"; change to LRU
26: \ if too slow. Using more buffers helps, too.
27:
28: \ I think I avoid the assumption 1 char = 1 here, but I have not tested this
29:
30: \ 1024 constant chars/block \ mandated by the standard
31:
32: require struct.fs
33:
34: struct
35: 1 cells: field buffer-block \ the block number
36: 1 cells: field buffer-fid \ the block's fid
37: 1 cells: field buffer-dirty \ the block dirty flag
38: chars/block chars: field block-buffer \ the data
39: 0 cells: field next-buffer
40: end-struct buffer-struct
41:
42: Variable block-buffers
43: Variable last-block
44:
45: $20 Value buffers
46:
47: User block-fid
48:
49: : block-cold
50: defers 'cold block-fid off last-block off
51: buffers buffer-struct drop * allocate throw dup block-buffers !
52: buffers buffer-struct drop * erase ;
53:
54: ' block-cold IS 'cold
55:
56: block-cold
57:
58: Defer flush-blocks
59:
60: : open-blocks ( addr u -- ) \ gforth
61: \g use the file, whose name is given by @var{addr u}, as blocks file
62: 2dup ['] open-path-file catch 0<>
63: if
64: 2drop r/w bin create-file throw
65: else
66: rot close-file throw 2dup file-status throw bin open-file throw
67: >r 2drop r>
68: then
69: block-fid @ IF flush-blocks block-fid @ close-file throw THEN
70: block-fid ! ;
71:
72: : use ( "file" -- ) \ gforth
73: \g use @var{file} as blocks file
74: name open-blocks ;
75:
76: \ the file is opened as binary file, since it either will contain text
77: \ without newlines or binary data
78: : get-block-fid ( -- fid )
79: block-fid @ 0=
80: if
81: s" blocks.fb" open-blocks
82: then
83: block-fid @ ;
84:
85: : block-position ( u -- )
86: \ positions the block file to the start of block u
87: 1- chars/block chars um* get-block-fid reposition-file throw ;
88:
89: : update ( -- )
90: last-block @ ?dup IF buffer-dirty on THEN ;
91:
92: : save-buffer ( buffer -- ) >r
93: r@ buffer-dirty @ r@ buffer-block @ 0<> and
94: if
95: r@ buffer-block @ block-position
96: r@ block-buffer chars/block r@ buffer-fid @ write-file throw
97: r@ buffer-dirty off
98: endif
99: rdrop ;
100:
101: : empty-buffer ( buffer -- )
102: buffer-block off ;
103:
104: : save-buffers ( -- ) block-buffers @
105: buffers 0 ?DO dup save-buffer next-buffer LOOP drop ;
106:
107: : empty-buffers ( -- ) block-buffers @
108: buffers 0 ?DO dup empty-buffer next-buffer LOOP drop ;
109:
110: : flush ( -- )
111: save-buffers
112: empty-buffers ;
113:
114: ' flush IS flush-blocks
115:
116: : get-buffer ( n -- a-addr )
117: buffers mod buffer-struct drop * block-buffers @ + ;
118:
119: : block ( u -- a-addr )
120: dup 0= -35 and throw
121: dup get-buffer >r
122: dup r@ buffer-block @ <>
123: r@ buffer-fid @ block-fid @ <> or
124: if
125: r@ save-buffer
126: dup block-position
127: r@ block-buffer chars/block get-block-fid read-file throw
128: \ clear the rest of the buffer if the file is too short
129: r@ block-buffer over chars + chars/block rot chars - blank
130: r@ buffer-block !
131: get-block-fid r@ buffer-fid !
132: else
133: drop
134: then
135: r> dup last-block ! block-buffer ;
136:
137: : buffer ( u -- a-addr )
138: \ reading in the block is unnecessary, but simpler
139: block ;
140:
141: User scr 0 scr !
142:
143: : updated? ( n -- f ) scr @ buffer
144: [ 0 buffer-dirty 0 block-buffer - ] Literal + @ ;
145:
146: : list ( u -- )
147: \ calling block again and again looks inefficient but is necessary
148: \ in a multitasking environment
149: dup scr !
150: ." Screen " u.
151: updated? 0= IF ." not " THEN ." modified " cr
152: 16 0
153: ?do
154: i 2 .r space scr @ block i 64 * chars + 64 type cr
155: loop ;
156:
157: : (source) ( -- addr len )
158: blk @ ?dup
159: IF block chars/block
160: ELSE tib #tib @
161: THEN ;
162:
163: ' (source) IS source
164:
165: : load ( i*x n -- j*x )
166: push-file
167: dup loadline ! blk ! >in off ( ['] ) interpret ( catch )
168: pop-file ( throw ) ;
169:
170: : thru ( i*x n1 n2 -- j*x )
171: 1+ swap 0 ?DO I load LOOP ;
172:
173: : +load ( i*x n -- j*x ) blk @ + load ;
174:
175: : +thru ( i*x n1 n2 -- j*x )
176: 1+ swap 0 ?DO I +load LOOP ;
177:
178: : --> ( -- ) refill drop ; immediate
179:
180: : block-included ( addr u -- )
181: block-fid @ >r block-fid off open-blocks
182: 1 load block-fid @ close-file throw flush
183: r> block-fid ! ;
184:
185: : include ( "name" -- )
186: name 2dup dup 3 - /string s" .fb" compare
187: 0= IF block-included ELSE included THEN ;
188:
189: get-current environment-wordlist set-current
190: true constant block
191: true constant block-ext
192: set-current
193:
194: : bye ['] flush catch drop bye ;
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