Annotation of gforth/struct.fs, revision 1.25

1.8       anton       1: \ data structures (like C structs)
                      2: 
1.24      anton       3: \ Copyright (C) 1995,1997,2000,2003,2007 Free Software Foundation, Inc.
1.8       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
1.25    ! anton       9: \ as published by the Free Software Foundation, either version 3
1.8       anton      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
1.25    ! anton      18: \ along with this program. If not, see http://www.gnu.org/licenses/.
1.8       anton      19: 
1.14      anton      20: : naligned ( addr1 n -- addr2 ) \ gforth
1.15      crook      21: \g @var{addr2} is the aligned version of @var{addr1} with respect to the
                     22: \g alignment @var{n}.
1.1       anton      23:  1- tuck +  swap invert and ;
1.14      anton      24: 
                     25: ' naligned alias nalign \ old name, obsolete
1.1       anton      26: 
1.11      anton      27: : dozerofield ( -- )
                     28:     \ a field that makes no change
                     29:     \ to enable accessing the offset with "['] <field> >body @" this
                     30:     \ is not implemented with "['] noop alias"
1.22      anton      31:     latest
1.11      anton      32:     if
                     33:        immediate
                     34:     then
1.12      anton      35: does> ( name execution: -- )
1.11      anton      36:     drop ;
                     37: 
1.12      anton      38: : field, ( align1 offset1 align size --  align2 offset2 )
1.13      anton      39:     swap rot over nalign dup , ( align1 size align offset )
                     40:     rot + >r nalign r> ;
1.12      anton      41: 
                     42: : create-field ( align1 offset1 align size --  align2 offset2 )
                     43:     create field, ;
                     44: 
                     45: : field ( align1 offset1 align size "name" --  align2 offset2 ) \ gforth
1.16      anton      46:     \g Create a field @var{name} with offset @var{offset1}, and the type
                     47:     \g given by @var{align size}. @var{offset2} is the offset of the
                     48:     \g next field, and @var{align2} is the alignment of all fields.@*
                     49:     \g @code{name} execution: @var{addr1} -- @var{addr2}.@*
                     50:     \g @var{addr2}=@var{addr1}+@var{offset1}
1.12      anton      51:     2 pick 
1.11      anton      52:     if \ field offset <> 0
                     53:        [IFDEF]  (Field)
                     54:            (Field)
                     55:        [ELSE]
                     56:            Header reveal dofield: cfa,
                     57:        [THEN]
                     58:     else
                     59:        create dozerofield
1.12      anton      60:     then
                     61:     field, ;
1.1       anton      62: 
1.12      anton      63: : end-struct ( align size "name" -- ) \ gforth
1.16      anton      64: \g Define a structure/type descriptor @var{name} with alignment
                     65: \g @var{align} and size @var{size1} (@var{size} rounded up to be a
                     66: \g multiple of @var{align}).@*
                     67: \g @code{name} execution: -- @var{align size1}@*
1.12      anton      68:     over nalign \ pad size to full alignment
                     69:     2constant ;
                     70: 
                     71: 1 chars 0 end-struct struct ( -- align size ) \ gforth
1.15      crook      72: \g An empty structure, used to start a structure definition.
1.12      anton      73: 
                     74: \ type descriptors
                     75: 1 aligned   1 cells   2constant cell% ( -- align size ) \ gforth
                     76: 1 chars     1 chars   2constant char% ( -- align size ) \ gforth
                     77: 1 faligned  1 floats  2constant float% ( -- align size ) \ gforth
                     78: 1 dfaligned 1 dfloats 2constant dfloat% ( -- align size ) \ gforth
                     79: 1 sfaligned 1 sfloats 2constant sfloat% ( -- align size ) \ gforth
                     80: cell% 2*              2constant double% ( -- align size ) \ gforth
                     81: 
                     82: \ memory allocation words
                     83: ' drop alias %alignment ( align size -- align ) \ gforth
1.15      crook      84: \g The alignment of the structure.
1.12      anton      85: ' nip alias %size ( align size -- size ) \ gforth
1.15      crook      86: \g The size of the structure.
1.12      anton      87: 
                     88: : %align ( align size -- ) \ gforth
1.15      crook      89:     \G Align the data space pointer to the alignment @var{align}. 
1.12      anton      90:     drop here swap nalign here - allot ;
                     91: 
                     92: : %allot ( align size -- addr ) \ gforth
1.15      crook      93:     \g Allot @var{size} address units of data space with alignment
                     94:     \g @var{align}; the resulting block of data is found at
                     95:     \g @var{addr}.
1.12      anton      96:     tuck %align
1.2       anton      97:     here swap allot ;
                     98: 
1.12      anton      99: : %allocate ( align size -- addr ior ) \ gforth
1.15      crook     100:     \g Allocate @var{size} address units with alignment @var{align},
1.12      anton     101:     \g similar to @code{allocate}.
                    102:     nip allocate ;
                    103: 
1.23      anton     104: : %alloc ( align size -- addr ) \ gforth
1.15      crook     105:     \g Allocate @var{size} address units with alignment @var{align},
                    106:     \g giving a data block at @var{addr}; @code{throw} an ior code
1.12      anton     107:     \g if not successful.
                    108:     %allocate throw ;

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