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Simplify macro that links dictionary entries

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Cesar Blum 2020-10-01 21:42:45 -07:00
parent 845744842d
commit d55d6bc190
1 changed files with 7 additions and 23 deletions
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30
sectorforth.asm
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@ -52,33 +52,17 @@ F_IMMEDIATE equ 0x80
F_HIDDEN equ 0x40 F_HIDDEN equ 0x40
LENMASK equ 0x1f LENMASK equ 0x1f
; Each dictionary entry needs a link to the previous entry. The ; Each dictionary entry needs a link to the previous entry. The
; initlink macro uses the nasm context stack to push a context and ; last entry links to zero, marking the end of the dictionary.
; define a context-local macro called %$link that represents the ; As dictionary entries are defined, link will be redefined to
; end of the dictionary. ; point to the previous entry.
%macro initlink 0 %define link 0
%push
%define %$link 0
%endmacro
initlink ; expand initlink so %$link is initialized
; The link macro links dictionary entries by pushing a new context
; and redefining %$link as a context-local label at the current
; location (address) in the code. It then writes a 16-bit data
; word with the value of %$link in the previous context (i.e. the
; previous expansion of link), effectively writing a link field to
; the previous location.
%macro link 0
%push
%$link:
dw %$$link
%endmacro
; defword lays out a dictionary entry where it is expanded. ; defword lays out a dictionary entry where it is expanded.
%macro defword 3-4 0 ; name, length, label, flags %macro defword 3-4 0 ; name, length, label, flags
word_%3: word_%3:
link ; link to previous word dw link ; link to previous word
%define link word_%3
db %4+%2 ; flags+length db %4+%2 ; flags+length
db %1 ; name db %1 ; name
%3: ; code starts here %3: ; code starts here