Annotation of gforth/blocks.fs, revision 1.9

1.5       pazsan      1: \ A less simple implementation of the blocks wordset. 
1.1       anton       2: 
1.7       anton       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
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
                     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
1.1       anton      48: 
1.5       pazsan     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 ;
1.1       anton      53: 
1.5       pazsan     54: ' block-cold IS 'cold
                     55: 
                     56: block-cold
                     57: 
                     58: Defer flush-file
                     59: 
                     60: : use-file ( addr u -- )
1.8       pazsan     61:     2dup ['] open-path-file catch 0<>
1.5       pazsan     62:     if
1.8       pazsan     63:        2drop r/w bin create-file throw
1.5       pazsan     64:     else
1.8       pazsan     65:        rot close-file throw  2dup file-status throw bin open-file throw
                     66:        >r 2drop r>
1.5       pazsan     67:     then
1.6       pazsan     68:     block-fid @ IF  flush-file block-fid @ close-file throw  THEN
1.5       pazsan     69:     block-fid ! ;
1.8       pazsan     70: 
                     71: : use ( "file" -- )
                     72:     name use-file ;
1.1       anton      73: 
1.3       anton      74: \ the file is opened as binary file, since it either will contain text
                     75: \ without newlines or binary data
1.1       anton      76: : get-block-fid ( -- fid )
                     77:     block-fid @ 0=
                     78:     if
1.5       pazsan     79:        s" blocks.fb" use-file
1.1       anton      80:     then
                     81:     block-fid @ ;
                     82: 
                     83: : block-position ( u -- )
                     84:     \ positions the block file to the start of block u
1.3       anton      85:     1- chars/block chars um* get-block-fid reposition-file throw ;
1.1       anton      86: 
                     87: : update ( -- )
1.5       pazsan     88:     last-block @ ?dup IF  buffer-dirty on  THEN ;
1.1       anton      89: 
1.5       pazsan     90: : save-buffer ( buffer -- ) >r
                     91:     r@ buffer-dirty @ r@ buffer-block @ 0<> and
1.1       anton      92:     if
1.5       pazsan     93:        r@ buffer-block @ block-position
                     94:        r@ block-buffer chars/block  r@ buffer-fid @  write-file throw
                     95:        r@ buffer-dirty off
                     96:     endif
                     97:     rdrop ;
                     98: 
                     99: : empty-buffer ( buffer -- )
                    100:     buffer-block off ;
                    101: 
                    102: : save-buffers  ( -- )    block-buffers @
                    103:     buffers 0 ?DO  dup save-buffer  next-buffer  LOOP  drop ;
1.1       anton     104: 
1.5       pazsan    105: : empty-buffers ( -- )    block-buffers @
                    106:     buffers 0 ?DO  dup empty-buffer  next-buffer  LOOP  drop ;
1.1       anton     107: 
                    108: : flush ( -- )
                    109:     save-buffers
                    110:     empty-buffers ;
                    111: 
1.5       pazsan    112: ' flush IS flush-file
                    113: 
                    114: : get-buffer ( n -- a-addr )
                    115:     buffers mod buffer-struct drop * block-buffers @ + ;
                    116: 
1.1       anton     117: : block ( u -- a-addr )
                    118:     dup 0= -35 and throw
1.5       pazsan    119:     dup get-buffer >r
                    120:     dup r@ buffer-block @ <>
1.9     ! pazsan    121:     r@ buffer-fid @ block-fid @ <> or
1.1       anton     122:     if
1.5       pazsan    123:        r@ save-buffer
1.1       anton     124:        dup block-position
1.5       pazsan    125:        r@ block-buffer chars/block get-block-fid read-file throw
1.1       anton     126:        \ clear the rest of the buffer if the file is too short
1.5       pazsan    127:        r@ block-buffer over chars + chars/block rot chars - blank
                    128:        r@ buffer-block !
                    129:        get-block-fid r@ buffer-fid !
1.1       anton     130:     else
                    131:        drop
                    132:     then
1.5       pazsan    133:     r> dup last-block ! block-buffer ;
1.1       anton     134: 
                    135: : buffer ( u -- a-addr )
                    136:     \ reading in the block is unnecessary, but simpler
                    137:     block ;
                    138: 
1.2       pazsan    139: User scr 0 scr !
1.1       anton     140: 
1.5       pazsan    141: : updated?  ( n -- f )   scr @ buffer
                    142:     [ 0 buffer-dirty 0 block-buffer - ] Literal + @ ;
                    143: 
1.1       anton     144: : list ( u -- )
                    145:     \ calling block again and again looks inefficient but is necessary
                    146:     \ in a multitasking environment
                    147:     dup scr !
1.5       pazsan    148:     ." Screen " u.
                    149:     updated?  0= IF ." not "  THEN  ." modified     " cr
1.1       anton     150:     16 0
                    151:     ?do
1.4       anton     152:        i 2 .r space scr @ block i 64 * chars + 64 type cr
1.1       anton     153:     loop ;
                    154: 
1.2       pazsan    155: : (source)  ( -- addr len )
                    156:   blk @ ?dup
                    157:   IF    block chars/block
                    158:   ELSE  tib #tib @
                    159:   THEN ;
                    160: 
                    161: ' (source) IS source
                    162: 
                    163: : load ( i*x n -- j*x )
                    164:   push-file
                    165:   dup loadline ! blk ! >in off ( ['] ) interpret ( catch )
                    166:   pop-file ( throw ) ;
1.1       anton     167: 
1.2       pazsan    168: : thru ( i*x n1 n2 -- j*x )
                    169:   1+ swap 0 ?DO  I load  LOOP ;
1.1       anton     170: 
1.2       pazsan    171: : +load ( i*x n -- j*x )  blk @ + load ;
                    172: 
                    173: : +thru ( i*x n1 n2 -- j*x )
                    174:   1+ swap 0 ?DO  I +load  LOOP ;
1.4       anton     175: 
1.5       pazsan    176: : --> ( -- )  refill drop ; immediate
                    177: 
                    178: : block-included ( addr u -- )
                    179:     block-fid @ >r block-fid off use-file
                    180:     1 load block-fid @ close-file throw flush
                    181:     r> block-fid ! ;
                    182: 
                    183: : include ( "name" -- )
                    184:     name 2dup dup 3 - /string s" .fb" compare
                    185:     0= IF  block-included  ELSE  included  THEN ;
                    186: 
1.4       anton     187: get-current environment-wordlist set-current
                    188: true constant block
                    189: true constant block-ext
                    190: set-current
1.5       pazsan    191: 
                    192: : bye  ['] flush catch drop bye ;

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