File:  [gforth] / gforth / kernel / vars.fs
Revision 1.25: download - view: text, annotated - select for diffs
Sun Oct 29 20:27:03 2000 UTC (20 years, 6 months ago) by pazsan
Branches: MAIN
CVS tags: HEAD
Added new input handling (OO approach). Only available if capability
new-input is true (so setting that to false in machpc.fs gets you the old
input handling back).

    1: \ VARS.FS      Kernal variables
    2: 
    3: \ Copyright (C) 1995,1996,1997,1998,2000 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., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
   20: 
   21: hex \ everything now hex!                               11may93jaw
   22: 
   23: \ important constants                                  17dec92py
   24: 
   25: \ dpANS6 (sect 3.1.3.1) says 
   26: \ "a true flag ... [is] a single-cell value with all bits set"
   27: \ better definition: 0 0= constant true ( no dependence on 2's compl)
   28:  -1 Constant true ( -- f ) \ core-ext
   29: \G @code{Constant} -- @i{f} is a cell with all bits set.
   30: \ see starts looking for primitives after this word!
   31: 
   32:   0 Constant false ( -- f ) \ core-ext
   33: \G @code{Constant} -- @i{f} is a cell with all bits clear.
   34: 
   35: [IFUNDEF] cell 
   36: 1 cells Constant cell ( -- u ) \ gforth
   37: \G @code{Constant} -- @code{1 cells}
   38: [THEN]
   39: 
   40: has? floating [IF]
   41: 1 floats Constant float ( -- u ) \ gforth
   42: \G @code{Constant} -- the number of address units corresponding to a floating-point number.
   43: [THEN]
   44: 
   45: 20 Constant bl ( -- c-char ) \ core b-l
   46: \G @i{c-char} is the character value for a space.
   47: \ used by docon:, must be constant
   48: 
   49: FF Constant /line
   50: 
   51: 40 Constant c/l
   52: 10 Constant l/s
   53: 400 Constant chars/block
   54: 
   55: 20 8 2* cells + 2 + cell+ constant word-pno-size ( -- u )
   56: create holdbuf word-pno-size chars allot
   57: holdbuf word-pno-size chars + aconstant holdbuf-end
   58: avariable holdptr holdbuf-end holdptr a!
   59: avariable holdend holdbuf-end holdend a!
   60: 
   61: 84 constant pad-minsize ( -- u )
   62: 
   63: $400 Value def#tib
   64: \G default size of terminal input buffer. Default size is 1K
   65: 
   66: \ that's enough so long
   67: 
   68: \ User variables                                       13feb93py
   69: 
   70: \ initialized by COLD
   71: 
   72: Create main-task  has? OS [IF] 100 [ELSE] 40 [THEN] cells allot
   73: 
   74: \ set user-pointer from cross-compiler right
   75: main-task 
   76: UNLOCK tup ! LOCK
   77: 
   78: Variable udp ( -- a-addr ) \ gforth
   79: \ user area size? -anton
   80: 
   81: AUser next-task        main-task next-task !
   82: AUser prev-task        main-task prev-task !
   83: AUser save-task        0 save-task !
   84: AUser sp0 ( -- a-addr ) \ gforth
   85: \G @code{User} variable -- initial value of the data stack pointer.
   86: \ sp0 is used by douser:, must be user
   87:     ' sp0 Alias s0 ( -- a-addr ) \ gforth
   88: \G OBSOLETE alias of @code{sp0}
   89: 
   90: AUser rp0 ( -- a-addr ) \ gforth
   91: \G @code{User} variable -- initial value of the return stack pointer.
   92:     ' rp0 Alias r0 ( -- a-addr ) \ gforth
   93: \G OBSOLETE alias of @code{rp0}
   94: 
   95: has? floating [IF]
   96: AUser fp0 ( -- a-addr ) \ gforth
   97: \G @code{User} variable -- initial value of the floating-point stack pointer.
   98: \ no f0, because this leads to unexpected results when using hex
   99: [THEN]
  100: 
  101: has? glocals [IF]
  102: AUser lp0 ( -- a-addr ) \ gforth
  103: \G @code{User} variable -- initial value of the locals stack pointer.
  104:     ' lp0 Alias l0 ( -- a-addr ) \ gforth
  105: \G OBSOLETE alias of @code{lp0}
  106: [THEN]
  107: 
  108: AUser handler	\ pointer to last throw frame
  109: has? backtrace [IF]
  110: User backtrace-empty \ true if the next THROW should store a backtrace
  111: AUser backtrace-rp0 \ rp at last call of interpret
  112: [THEN]
  113: \ AUser output
  114: \ AUser input
  115: 
  116: AUser errorhandler
  117: 
  118: AUser "error            0 "error !
  119: 
  120: has? new-input [IF]
  121:     User current-input
  122: [ELSE]
  123:     [IFUNDEF] #tib		\ in ec-Version we may define this ourself
  124: 	User tibstack		\ saves >tib in execute
  125: 	User >tib		\ pointer to terminal input buffer
  126: 	User #tib ( -- a-addr ) \ core-ext number-t-i-b
  127: 	\G @code{User} variable -- @i{a-addr} is the address of a cell containing
  128: 	\G the number of characters in the terminal input buffer.
  129: 	\G OBSOLESCENT: @code{source} superceeds the function of this word.
  130: 	
  131: 	User >in ( -- a-addr ) \ core to-in
  132: 	\G @code{User} variable -- @i{a-addr} is the address of a cell containing the
  133: 	\G char offset from the start of the input buffer to the start of the
  134: 	\G parse area.
  135: 	0 >in ! \ char number currently processed in tib
  136:     [THEN]
  137: 
  138: has? file [IF]
  139:  User blk ( -- a-addr ) \ block b-l-k
  140:  \G @code{User} variable -- @i{a-addr} is the address of a cell containing zero
  141:  \G (in which case the input source is not a block and can be identified
  142:  \G by @code{source-id}) or the number of the block currently being
  143:  \G interpreted. A Standard program should not alter @code{blk} directly.
  144: 			0 blk !
  145: 
  146:  User loadfile          0 loadfile !
  147: 
  148:  User loadfilename#	0 loadfilename# !
  149: 
  150:  User loadline          \ number of the currently interpreted
  151:                         \ (in TIB) line if the interpretation
  152:                         \ is in a textfile
  153:                         \ the first line is 1
  154: 
  155: 2User linestart         \ starting file postition of
  156:                         \ the current interpreted line (in TIB)
  157: [THEN]
  158: [THEN]
  159: 
  160:  User base ( -- a-addr ) \ core
  161:  \G @code{User} variable -- @i{a-addr} is the address of a cell that stores the
  162:  \G number base used by default for number conversion during input and output.
  163:                         A base !
  164:  User dpl ( -- a-addr ) \ gforth
  165:  \G @code{User} variable -- @i{a-addr} is the address of a cell that stores the 		
  166:  \G position of the decimal point in the most recent numeric conversion.
  167:  \G Initialised to -1. After the conversion of a number containing no
  168:  \G decimal point, @code{@ dpl} is -1. After the conversion of @code{2.} it holds
  169:  \G 0. After the conversion of 234123.9 it contains 1, and so forth.
  170:  -1 dpl !
  171: 
  172:  User state ( -- a-addr ) \ core,tools-ext
  173:  \G @code{User} variable -- @i{a-addr} is the address of a cell
  174:  \G containing the compilation state flag. 0 => interpreting, -1 =>
  175:  \G compiling.  A program shall not directly alter the value of
  176:  \G @code{state}. The following Standard words alter the value in
  177:  \G @code{state}: @code{:} (colon) @code{;} (semicolon) @code{abort}
  178:  \G @code{quit} @code{:noname} @code{[} (left-bracket) @code{]}
  179:  \G (right-bracket) @code{;code}. Don't use @code{state}! For an
  180:  \G alternative see @ref{Interpretation and Compilation Semantics}.
  181:  \ Recommended reading: @cite{@code{State}-smartness--Why it is evil
  182:  \ and how to exorcise it},
  183:  \ @url{http://www.complang.tuwien.ac.at/papers/ertl98.ps.gz}; short
  184:  \ version: Don't use @code{state}!
  185:  0 state !
  186: 
  187: AUser normal-dp		\ the usual dictionary pointer
  188: AUser dpp		normal-dp dpp !
  189: 			\ the pointer to the current dictionary pointer
  190:                         \ ist reset to normal-dp on (doerror)
  191:                         \  (i.e. any throw caught by quit)
  192: AUser LastCFA
  193: AUser Last
  194: 
  195: has? glocals [IF]
  196: User locals-size \ this is the current size of the locals stack
  197: 		 \ frame of the current word
  198: [THEN]
  199: 

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