File:  [gforth] / gforth / struct.fs
Revision 1.21: download - view: text, annotated - select for diffs
Sun Mar 9 15:16:56 2003 UTC (16 years, 8 months ago) by anton
Branches: MAIN
CVS tags: v0-6-1, v0-6-0, HEAD
updated copyright years

    1: \ data structures (like C structs)
    2: 
    3: \ Copyright (C) 1995,1997,2000,2003 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: : naligned ( addr1 n -- addr2 ) \ gforth
   22: \g @var{addr2} is the aligned version of @var{addr1} with respect to the
   23: \g alignment @var{n}.
   24:  1- tuck +  swap invert and ;
   25: 
   26: ' naligned alias nalign \ old name, obsolete
   27: 
   28: : dozerofield ( -- )
   29:     \ a field that makes no change
   30:     \ to enable accessing the offset with "['] <field> >body @" this
   31:     \ is not implemented with "['] noop alias"
   32:     last @
   33:     if
   34: 	immediate
   35:     then
   36: does> ( name execution: -- )
   37:     drop ;
   38: 
   39: : field, ( align1 offset1 align size --  align2 offset2 )
   40:     swap rot over nalign dup , ( align1 size align offset )
   41:     rot + >r nalign r> ;
   42: 
   43: : create-field ( align1 offset1 align size --  align2 offset2 )
   44:     create field, ;
   45: 
   46: : field ( align1 offset1 align size "name" --  align2 offset2 ) \ gforth
   47:     \g Create a field @var{name} with offset @var{offset1}, and the type
   48:     \g given by @var{align size}. @var{offset2} is the offset of the
   49:     \g next field, and @var{align2} is the alignment of all fields.@*
   50:     \g @code{name} execution: @var{addr1} -- @var{addr2}.@*
   51:     \g @var{addr2}=@var{addr1}+@var{offset1}
   52:     2 pick 
   53:     if \ field offset <> 0
   54: 	[IFDEF]  (Field)
   55: 	    (Field)
   56: 	[ELSE]
   57: 	    Header reveal dofield: cfa,
   58: 	[THEN]
   59:     else
   60: 	create dozerofield
   61:     then
   62:     field, ;
   63: 
   64: : end-struct ( align size "name" -- ) \ gforth
   65: \g Define a structure/type descriptor @var{name} with alignment
   66: \g @var{align} and size @var{size1} (@var{size} rounded up to be a
   67: \g multiple of @var{align}).@*
   68: \g @code{name} execution: -- @var{align size1}@*
   69:     over nalign \ pad size to full alignment
   70:     2constant ;
   71: 
   72: 1 chars 0 end-struct struct ( -- align size ) \ gforth
   73: \g An empty structure, used to start a structure definition.
   74: 
   75: \ type descriptors
   76: 1 aligned   1 cells   2constant cell% ( -- align size ) \ gforth
   77: 1 chars     1 chars   2constant char% ( -- align size ) \ gforth
   78: 1 faligned  1 floats  2constant float% ( -- align size ) \ gforth
   79: 1 dfaligned 1 dfloats 2constant dfloat% ( -- align size ) \ gforth
   80: 1 sfaligned 1 sfloats 2constant sfloat% ( -- align size ) \ gforth
   81: cell% 2*              2constant double% ( -- align size ) \ gforth
   82: 
   83: \ memory allocation words
   84: ' drop alias %alignment ( align size -- align ) \ gforth
   85: \g The alignment of the structure.
   86: ' nip alias %size ( align size -- size ) \ gforth
   87: \g The size of the structure.
   88: 
   89: : %align ( align size -- ) \ gforth
   90:     \G Align the data space pointer to the alignment @var{align}. 
   91:     drop here swap nalign here - allot ;
   92: 
   93: : %allot ( align size -- addr ) \ gforth
   94:     \g Allot @var{size} address units of data space with alignment
   95:     \g @var{align}; the resulting block of data is found at
   96:     \g @var{addr}.
   97:     tuck %align
   98:     here swap allot ;
   99: 
  100: : %allocate ( align size -- addr ior ) \ gforth
  101:     \g Allocate @var{size} address units with alignment @var{align},
  102:     \g similar to @code{allocate}.
  103:     nip allocate ;
  104: 
  105: : %alloc ( size align -- addr ) \ gforth
  106:     \g Allocate @var{size} address units with alignment @var{align},
  107:     \g giving a data block at @var{addr}; @code{throw} an ior code
  108:     \g if not successful.
  109:     %allocate throw ;

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