File:  [gforth] / gforth / blocks.fs
Revision 1.60: download - view: text, annotated - select for diffs
Thu Feb 16 17:13:04 2012 UTC (7 years, 5 months ago) by anton
Branches: MAIN
CVS tags: HEAD
fixed http://savannah.gnu.org/bugs/?35540 (confusing doc)

    1: \ A less simple implementation of the blocks wordset. 
    2: 
    3: \ Copyright (C) 1995,1996,1997,1998,2000,2003,2006,2007,2008,2011 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 3
   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, see http://www.gnu.org/licenses/.
   19: 
   20: 
   21: \ A more efficient implementation would use mmap on OSs that
   22: \ provide it and many buffers on OSs that do not provide mmap.
   23: 
   24: \ Now, the replacement algorithm is "direct mapped"; change to LRU
   25: \ if too slow. Using more buffers helps, too.
   26: 
   27: \ I think I avoid the assumption 1 char = 1 here, but I have not tested this
   28: 
   29: \ 1024 constant chars/block \ mandated by the standard
   30: 
   31: require struct.fs
   32: 
   33: struct
   34:     cell%		field buffer-block   \ the block number
   35:     cell%		field buffer-fid     \ the block's fid
   36:     cell%		field buffer-dirty   \ the block dirty flag
   37:     char% chars/block * field block-buffer   \ the data
   38:     cell% 0 *		field next-buffer
   39: end-struct buffer-struct
   40: 
   41: Variable block-buffers
   42: Variable last-block
   43: 
   44: $20 Value buffers
   45: 
   46: \ limit block files to 2GB; gforth <0.6.0 erases larger block files on
   47: \ 32-bit systems
   48: $200000 Value block-limit
   49: 
   50: User block-fid
   51: User block-offset ( -- addr ) \ gforth
   52: \G User variable containing the number of the first block (default
   53: \G since 0.5.0: 0).  Block files created with Gforth versions before
   54: \G 0.5.0 have the offset 1.  If you use these files you can: @code{1
   55: \G offset !}; or add 1 to every block number used; or prepend 1024
   56: \G characters to the file.
   57: 0 block-offset !  \ store 1 here fore 0.4.0 compatibility
   58: 
   59: ' block-offset alias offset \ !! eliminate this?
   60: 
   61: : block-cold ( -- )
   62:     block-fid off  last-block off
   63:     buffer-struct buffers * %alloc dup block-buffers ! ( addr )
   64:     buffer-struct %size buffers * erase ;
   65: 
   66: :noname ( -- )
   67:     defers 'cold
   68:     block-cold
   69: ; is 'cold
   70: 
   71: block-cold
   72: 
   73: Defer flush-blocks ( -- ) \ gforth
   74: 
   75: : open-blocks ( c-addr u -- ) \ gforth
   76: \g Use the file, whose name is given by @i{c-addr u}, as the blocks file.
   77:     try ( c-addr u )
   78: 	2dup open-fpath-file throw
   79: 	rot close-file throw  2dup file-status throw bin open-file throw
   80: 	>r 2drop r>
   81:     endtry-iferror ( c-addr u ior )
   82: 	>r 2dup file-status nip 0= r> and throw \ does it really not exist?
   83: 	r/w bin create-file throw
   84:     then
   85:     block-fid @ IF
   86: 	flush-blocks block-fid @ close-file throw
   87:     THEN
   88:     block-fid ! ;
   89: 
   90: : use ( "file" -- ) \ gforth
   91:     \g Use @i{file} as the blocks file.
   92:     name name-too-short? open-blocks ;
   93: 
   94: \ the file is opened as binary file, since it either will contain text
   95: \ without newlines or binary data
   96: : get-block-fid ( -- wfileid ) \ gforth
   97:     \G Return the file-id of the current blocks file. If no blocks
   98:     \G file has been opened, use @file{blocks.fb} as the default
   99:     \G blocks file.
  100:     block-fid @ 0=
  101:     if
  102: 	s" blocks.fb" open-blocks
  103:     then
  104:     block-fid @ ;
  105: 
  106: : block-position ( u -- ) \ block
  107: \G Position the block file to the start of block @i{u}.
  108:     dup block-limit u>= -35 and throw
  109:     offset @ - chars/block chars um* get-block-fid reposition-file throw ;
  110: 
  111: : update ( -- ) \ block
  112:     \G Mark the state of the current block buffer as assigned-dirty.
  113:     last-block @ ?dup IF  buffer-dirty on  THEN ;
  114: 
  115: : save-buffer ( buffer -- ) \ gforth
  116:     >r
  117:     r@ buffer-dirty @
  118:     if
  119: 	r@ buffer-block @ block-position
  120: 	r@ block-buffer chars/block  r@ buffer-fid @  write-file throw
  121: 	r@ buffer-fid @ flush-file throw
  122: 	r@ buffer-dirty off 
  123:     endif
  124:     rdrop ;
  125: 
  126: : empty-buffer ( buffer -- ) \ gforth
  127:     dup buffer-block on buffer-dirty off ;
  128: 
  129: : save-buffers  ( -- ) \ block
  130:     \G Transfer the contents of each @code{update}d block buffer to
  131:     \G mass storage, then mark all block buffers as assigned-clean.
  132:     block-buffers @
  133:     buffers 0 ?DO dup save-buffer next-buffer LOOP drop ;
  134: 
  135: : empty-buffers ( -- ) \ block-ext
  136:     \G Mark all block buffers as unassigned; if any had been marked as
  137:     \G assigned-dirty (by @code{update}), the changes to those blocks
  138:     \G will be lost.
  139:     block-buffers @
  140:     buffers 0 ?DO dup empty-buffer next-buffer LOOP drop ;
  141: 
  142: : flush ( -- ) \ block
  143:     \G Perform the functions of @code{save-buffers} then
  144:     \G @code{empty-buffers}.
  145:     save-buffers
  146:     empty-buffers ;
  147: 
  148: ' flush IS flush-blocks
  149: 
  150: : get-buffer ( u -- a-addr ) \ gforth
  151:     0 buffers um/mod drop buffer-struct %size * block-buffers @ + ;
  152: 
  153: : block ( u -- a-addr ) \ block
  154:     \G If a block buffer is assigned for block @i{u}, return its
  155:     \G start address, @i{a-addr}. Otherwise, assign a block buffer
  156:     \G for block @i{u} (if the assigned block buffer has been
  157:     \G @code{update}d, transfer the contents to mass storage), read
  158:     \G the block into the block buffer and return its start address,
  159:     \G @i{a-addr}.
  160:     dup offset @ u< -35 and throw
  161:     dup get-buffer >r
  162:     dup r@ buffer-block @ <>
  163:     r@ buffer-fid @ block-fid @ <> or
  164:     if
  165: 	r@ save-buffer
  166: 	dup block-position
  167: 	r@ block-buffer chars/block get-block-fid read-file throw
  168: 	\ clear the rest of the buffer if the file is too short
  169: 	r@ block-buffer over chars + chars/block rot chars - blank
  170: 	r@ buffer-block !
  171: 	get-block-fid r@ buffer-fid !
  172:     else
  173: 	drop
  174:     then
  175:     r> dup last-block ! block-buffer ;
  176: 
  177: : buffer ( u -- a-addr ) \ block
  178:     \G If a block buffer is assigned for block @i{u}, return its
  179:     \G start address, @i{a-addr}. Otherwise, assign a block buffer
  180:     \G for block @i{u} (if the assigned block buffer has been
  181:     \G @code{update}d, transfer the contents to mass storage) and
  182:     \G return its start address, @i{a-addr}.  The subtle difference
  183:     \G between @code{buffer} and @code{block} mean that you should
  184:     \G only use @code{buffer} if you don't care about the previous
  185:     \G contents of block @i{u}. In Gforth, this simply calls
  186:     \G @code{block}.
  187:     \ reading in the block is unnecessary, but simpler
  188:     block ;
  189: 
  190: User scr ( -- a-addr ) \ block-ext s-c-r
  191:     \G @code{User} variable containing
  192:     \G the block number of the block most recently processed by
  193:     \G @code{list}.
  194: 0 scr !
  195: 
  196: \ nac31Mar1999 moved "scr @" to list to make the stack comment correct
  197: : updated?  ( n -- f ) \ gforth
  198:     \G Return true if @code{updated} has been used to mark block @i{n}
  199:     \G as assigned-dirty.
  200:     buffer
  201:     [ 0 buffer-dirty 0 block-buffer - ] Literal + @ ;
  202: 
  203: : list ( u -- ) \ block-ext
  204:     \G Display block @i{u}. In Gforth, the block is displayed as 16
  205:     \G numbered lines, each of 64 characters.
  206:     \ calling block again and again looks inefficient but is necessary
  207:     \ in a multitasking environment
  208:     dup scr !
  209:     ." Screen " u.
  210:     scr @ updated?  0= IF ." not "  THEN  ." modified     " cr
  211:     16 0
  212:     ?do
  213: 	i 2 .r space scr @ block i 64 * chars + 64 type cr
  214:     loop ;
  215: 
  216: [IFDEF] current-input
  217: :noname  2 <> -12 and throw >in ! blk ! ;
  218:                               \ restore-input
  219: :noname  blk @ >in @ 2 ;      \ save-input
  220: :noname  2 ;                  \ source-id "*a block*"
  221: :noname  1 blk +! 1 loadline +! >in off true ;      \ refill
  222: :noname  blk @ block chars/block ;  \ source
  223: 
  224: Create block-input   A, A, A, A, A,
  225: 
  226: : load  ( i*x u -- j*x ) \ block
  227:     \g Text-interpret block @i{u}.  Block 0 cannot be @code{load}ed.
  228:     dup 0= -35 and throw
  229:     block-input 0 new-tib dup loadline ! blk !  s" * a block*" loadfilename 2!
  230:     ['] interpret catch pop-file throw ;
  231: [ELSE]
  232: : (source)  ( -- c-addr u )
  233:   blk @ ?dup
  234:   IF    block chars/block
  235:   ELSE  tib #tib @
  236:   THEN ;
  237: 
  238: ' (source) IS source ( -- c-addr u ) \ core
  239: \G @i{c-addr} is the address of the input buffer and @i{u} is the
  240: \G number of characters in it.
  241: 
  242: : load ( i*x u -- j*x ) \ block
  243:     \g Text-interpret block @i{u}.  Block 0 cannot be @code{load}ed.
  244:     dup 0= -35 and throw
  245:     s" * a block*" loadfilename>r
  246:     push-file
  247:     dup loadline ! blk ! >in off ['] interpret catch
  248:     pop-file
  249:     r>loadfilename
  250:     throw ;
  251: [THEN]
  252: 
  253: : thru ( i*x n1 n2 -- j*x ) \ block-ext
  254:     \G @code{load} the blocks @i{n1} through @i{n2} in sequence.
  255:     1+ swap ?DO  I load  LOOP ;
  256: 
  257: : +load ( i*x n -- j*x ) \ gforth
  258:     \G Used within a block to load the block specified as the
  259:     \G current block + @i{n}.
  260:     blk @ + load ;
  261: 
  262: : +thru ( i*x n1 n2 -- j*x ) \ gforth
  263:     \G Used within a block to load the range of blocks specified as the
  264:     \G current block + @i{n1} thru the current block + @i{n2}.
  265:     1+ swap ?DO  I +load  LOOP ;
  266: 
  267: : --> ( -- ) \ gforthman- gforth chain
  268:     \G If this symbol is encountered whilst loading block @i{n},
  269:     \G discard the remainder of the block and load block @i{n+1}. Used
  270:     \G for chaining multiple blocks together as a single loadable
  271:     \G unit.  Not recommended, because it destroys the independence of
  272:     \G loading.  Use @code{thru} (which is standard) or @code{+thru}
  273:     \G instead.
  274:     refill drop ; immediate
  275: 
  276: : block-included ( a-addr u -- ) \ gforth
  277:     \G Use within a block that is to be processed by @code{load}. Save
  278:     \G the current blocks file specification, open the blocks file
  279:     \G specified by @i{a-addr u} and @code{load} block 1 from that
  280:     \G file (which may in turn chain or load other blocks). Finally,
  281:     \G close the blocks file and restore the original blocks file.
  282:     block-fid @ >r block-fid off open-blocks
  283:     1 load block-fid @ close-file throw flush
  284:     r> block-fid ! ;
  285: 
  286: \ thrown out because it may provide unpleasant surprises - anton
  287: \ : include ( "name" -- )
  288: \     name 2dup dup 3 - /string s" .fb" compare
  289: \     0= IF  block-included  ELSE  included  THEN ;
  290: 
  291: get-current environment-wordlist set-current
  292: true constant block \ environment- environment
  293: true constant block-ext
  294: set-current
  295: 
  296: : bye ( -- ) \ tools-ext
  297:   \G Return control to the host operating system (if any).
  298:   ['] flush catch drop bye ;

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