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Annotation of gforth/kernel/vars.fs, revision 1.12

1.1       anton       1: \ VARS.FS      Kernal variables
                      2: 
1.6       anton       3: \ Copyright (C) 1995,1996,1997,1998 Free Software Foundation, Inc.
1.1       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: 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)
1.10      crook      28:  -1 Constant true ( -- f ) \ core-ext
                     29: \G CONSTANT: 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 CONSTANT: f is a cell with all bits clear.
1.1       anton      34: 
                     35: 1 cells Constant cell ( -- u ) \ gforth
                     36: 1 floats Constant float ( -- u ) \ gforth
                     37: 
1.10      crook      38: 20 Constant bl ( -- c-char ) \ core
                     39: \G c-char is the character value for a space.
                     40: \ used by docon:, must be constant
1.1       anton      41: 
                     42: FF Constant /line
                     43: 
                     44: 40 Constant c/l
                     45: 10 Constant l/s
                     46: 400 Constant chars/block
                     47: 
1.2       anton      48: $20 8 2* cells + 2 + cell+ constant word-pno-size ( -- u )
1.11      anton      49: create holdbuf word-pno-size chars allot
                     50: holdbuf word-pno-size chars + aconstant holdbuf-end
                     51: avariable holdptr holdbuf-end holdptr a!
1.12    ! anton      52: avariable holdend holdbuf-end holdend a!
1.11      anton      53: 
1.2       anton      54: 84 constant pad-minsize ( -- u )
1.11      anton      55: 
1.2       anton      56: 
1.1       anton      57: \ that's enough so long
                     58: 
                     59: \ User variables                                       13feb93py
                     60: 
                     61: \ initialized by COLD
                     62: 
1.7       pazsan     63: Create main-task  has? OS [IF] 100 [ELSE] 40 [THEN] cells allot
1.3       jwilke     64: 
                     65: \ set user-pointer from cross-compiler right
                     66: main-task 
                     67: UNLOCK tup ! LOCK
1.1       anton      68: 
1.8       anton      69: Variable udp \ user area size? -anton
1.1       anton      70: 
                     71: AUser next-task        main-task next-task !
                     72: AUser prev-task        main-task prev-task !
                     73: AUser save-task        0 save-task !
1.10      crook      74: AUser sp0 ( -- a-addr ) \ gforth
                     75: \G USER VARIABLE: Initial value of the data stack pointer.
                     76: \ sp0 is used by douser:, must be user
                     77:     ' sp0 Alias s0 ( -- a-addr ) \ gforth
                     78: \G OBSOLETE alias of @code{sp0}
                     79: 
                     80: AUser rp0 ( -- a-addr ) \ gforth
                     81: \G USER VARIABLE: Initial value of the return stack pointer.
                     82:     ' rp0 Alias r0 ( -- a-addr ) \ gforth
                     83: \G OBSOLETE alias of @code{rp0}
                     84: 
                     85: AUser fp0 ( -- a-addr ) \ gforth
                     86: \G USER VARIABLE: Initial value of the floating-point stack pointer.
                     87: \ no f0, because this leads to unexpected results when using hex
                     88: 
                     89: AUser lp0 ( -- a-addr ) \ gforth
                     90: \G USER VARIABLE: Initial value of the locals stack pointer.
                     91:     ' lp0 Alias l0 ( -- a-addr ) \ gforth
                     92: \G OBSOLETE alias of @code{lp0}
                     93: 
1.3       jwilke     94: AUser handler  \ pointer to last throw frame
1.9       anton      95: AUser backtrace-empty \ true if the next THROW should store a backtrace
1.1       anton      96: \ AUser output
                     97: \ AUser input
                     98: 
                     99: AUser errorhandler
                    100: 
                    101: AUser "error            0 "error !
                    102: 
1.3       jwilke    103: [IFUNDEF] #tib         \ in ec-Version we may define this ourself
                    104:  User tibstack         \ saves >tib in execute
                    105:  User >tib             \ pointer to terminal input buffer
1.10      crook     106:  User #tib ( -- a-addr ) \ core-ext
                    107:  \G USER VARIABLE: a-addr is the address of a cell containing
                    108:  \G the number of characters in the terminal input buffer.
                    109:  \G OBSOLESCENT: @code{source} superceeds the function of this word.
                    110: 
                    111:  User >in ( -- a-addr ) \ core
                    112:  \G USER VARIABLE: a-addr is the address of a cell containing the
                    113:  \G char offset from the start of the terminal input buffer to the
                    114:  \G start of the parse area
                    115:                         0 >in ! \ char number currently processed in tib
1.3       jwilke    116: [THEN]
1.7       pazsan    117: has? file [IF]
1.10      crook     118:  User blk ( -- a-addr ) \ block
                    119:  \G USER VARIABLE: a-addr is the address of a cell containing zero
                    120:  \G (in which case the input source is not a block and can be identified
                    121:  \G by @code{source-id}) or the number of the block currently being
                    122:  \G interpreted. A Standard program should not alter @code{blk} directly.
                    123:                        0 blk !
                    124: 
1.1       anton     125:  User loadfile          0 loadfile !
                    126: 
                    127:  User loadfilename#    0 loadfilename# !
                    128: 
                    129:  User loadline          \ number of the currently interpreted
                    130:                         \ (in TIB) line if the interpretation
                    131:                         \ is in a textfile
                    132:                         \ the first line is 1
                    133: 
                    134: 2User linestart         \ starting file postition of
                    135:                         \ the current interpreted line (in TIB)
1.7       pazsan    136: [THEN]
1.1       anton     137: 
1.10      crook     138:  User base ( -- a-addr ) \ core
                    139:  \G USER VARIABLE: a-addr is the address of a cell that stores the
                    140:  \G number base used by default for number conversion during input and output.
                    141:                         A base !
1.1       anton     142:  User dpl               -1 dpl !
                    143: 
1.10      crook     144:  User state ( -- a-addr ) \ core,tools-ext
1.12    ! anton     145:  \G Recommended reading: @cite{@code{State}-smartness--Why it is evil
        !           146:  \G and how to exorcise it},
        !           147:  \G @url{http://www.complang.tuwien.ac.at/papers/ertl98.ps.gz}; short
        !           148:  \G version: Don't use @code{state}! @xref{Interpretation and
        !           149:  \G Compilation Semantics} for an alternative. USER VARIABLE: a-addr
        !           150:  \G is the address of a cell containing the compilation state flag. 0
        !           151:  \G => interpreting, -1 => compiling.  A program shall not directly
        !           152:  \G alter the value of @code{state}. The following Standard words
        !           153:  \G alter the value in @code{state}: @code{:} (colon) @code{;}
        !           154:  \G (semicolon) @code{abort} @code{quit} @code{:noname} @code{[}
        !           155:  \G (left-bracket) @code{]} (right-bracket) @code{;code}
1.10      crook     156:                        0 state !
                    157: 
1.1       anton     158: AUser normal-dp                \ the usual dictionary pointer
                    159: AUser dpp              normal-dp dpp !
                    160:                        \ the pointer to the current dictionary pointer
                    161:                         \ ist reset to normal-dp on (doerror)
                    162:                         \  (i.e. any throw caught by quit)
                    163: AUser LastCFA
                    164: AUser Last
                    165: 
1.7       pazsan    166: has? glocals [IF]
1.1       anton     167: User locals-size \ this is the current size of the locals stack
                    168:                 \ frame of the current word
1.7       pazsan    169: [THEN]
1.1       anton     170: