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Hash :
1a08f436
Author :
Date :
2010-08-25T09:23:17
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\ loclabel.fth 2.10 02/05/02
\ Copyright 1985-1990 Bradley Forthware
\ Copyright 1990-2002 Sun Microsystems, Inc. All Rights Reserved
\ Copyright Use is subject to license terms.
\ Local labels for the assembler.
\ A local label can be inserted in an assembly-language program
\ to mark a position. A relative branch instruction can then reference
\ that location by its local name.
\
\ Local label names: 0 L: 1 L: 2 L: 3 L: etc.
\ Local label forward references: 0 F: 1 F: etc
\ Local label backward references: 0 B: 1 B: etc
\
\ There are 5 local labels, numbered 0 to 4.
\ Each local label may be referenced from up to 10 locations.
\
decimal
also assembler definitions
headerless
20 constant #references-max
10 constant #labels-max
#labels-max #references-max * /n* buffer: references
#labels-max /n* buffer: local-labels
#labels-max /n* buffer: next-references
: >reference ( index -- adr ) /n* #references-max * references + ;
: >label ( index -- adr ) local-labels swap na+ ;
: >next-reference ( index -- adr ) next-references swap na+ ;
: resolve-forward-references ( label# -- )
dup >next-reference @
[ also forth ] swap [ previous ] >reference
?do i @ >resolve /n +loop
;
\ Erase all forward references from this label
: clear-label ( label# -- ) dup >reference swap >next-reference ! ;
headers
: L: ( label# -- )
dup resolve-forward-references ( label# )
dup >label over >next-reference ! ( label# )
dup clear-label ( label# )
>label <mark [ also forth ] swap [ previous ] !
;
: B: ( label# -- adr ) \ Find the address of a backward reference
>label @ <resolve
;
: F: ( label# -- adr ) \ Remember a forward reference
>mark
over >next-reference @ !
/n [ also forth ] swap [ previous ] >next-reference +!
here \ the address we leave is a dummy
;
headerless
: init-labels ( -- )
#labels-max 0 do i clear-label loop
;
init-labels
[ifexist] do-label-hook
' init-labels is do-label-hook
[else]
where ." Bootstrap code.." cr
\ Bootstrapping..
also forth definitions
: code code [ also assembler ] init-labels [ previous ] ;
: label label [ also assembler ] init-labels [ previous ] ;
previous definitions
[then]
previous definitions