Annotation of gforth/struct.fs, revision 1.17
1.8 anton 1: \ data structures (like C structs)
2:
1.17 ! anton 3: \ Copyright (C) 1995,1997,2000 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
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:
1.14 anton 21: : naligned ( addr1 n -- addr2 ) \ gforth
1.15 crook 22: \g @var{addr2} is the aligned version of @var{addr1} with respect to the
23: \g alignment @var{n}.
1.1 anton 24: 1- tuck + swap invert and ;
1.14 anton 25:
26: ' naligned alias nalign \ old name, obsolete
1.1 anton 27:
1.11 anton 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
1.12 anton 36: does> ( name execution: -- )
1.11 anton 37: drop ;
38:
1.12 anton 39: : field, ( align1 offset1 align size -- align2 offset2 )
1.13 anton 40: swap rot over nalign dup , ( align1 size align offset )
41: rot + >r nalign r> ;
1.12 anton 42:
43: : create-field ( align1 offset1 align size -- align2 offset2 )
44: create field, ;
45:
46: : field ( align1 offset1 align size "name" -- align2 offset2 ) \ gforth
1.16 anton 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}
1.12 anton 52: 2 pick
1.11 anton 53: if \ field offset <> 0
54: [IFDEF] (Field)
55: (Field)
56: [ELSE]
57: Header reveal dofield: cfa,
58: [THEN]
59: else
60: create dozerofield
1.12 anton 61: then
62: field, ;
1.1 anton 63:
1.12 anton 64: : end-struct ( align size "name" -- ) \ gforth
1.16 anton 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}@*
1.12 anton 69: over nalign \ pad size to full alignment
70: 2constant ;
71:
72: 1 chars 0 end-struct struct ( -- align size ) \ gforth
1.15 crook 73: \g An empty structure, used to start a structure definition.
1.12 anton 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
1.15 crook 85: \g The alignment of the structure.
1.12 anton 86: ' nip alias %size ( align size -- size ) \ gforth
1.15 crook 87: \g The size of the structure.
1.12 anton 88:
89: : %align ( align size -- ) \ gforth
1.15 crook 90: \G Align the data space pointer to the alignment @var{align}.
1.12 anton 91: drop here swap nalign here - allot ;
92:
93: : %allot ( align size -- addr ) \ gforth
1.15 crook 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}.
1.12 anton 97: tuck %align
1.2 anton 98: here swap allot ;
99:
1.12 anton 100: : %allocate ( align size -- addr ior ) \ gforth
1.15 crook 101: \g Allocate @var{size} address units with alignment @var{align},
1.12 anton 102: \g similar to @code{allocate}.
103: nip allocate ;
104:
105: : %alloc ( size align -- addr ) \ gforth
1.15 crook 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
1.12 anton 108: \g if not successful.
109: %allocate throw ;
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