collapseos/apps/zasm/directive.asm

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; *** CONSTS ***
.equ D_DB 0x00
.equ D_DW 0x01
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.equ D_EQU 0x02
.equ D_BAD 0xff
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; *** Variables ***
.equ DIREC_SCRATCHPAD DIREC_RAMSTART
.equ DIREC_RAMEND DIREC_SCRATCHPAD+SCRATCHPAD_SIZE
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; *** CODE ***
; 4 bytes per row, fill with zero
directiveNames:
.db ".DB", 0
.db ".DW", 0
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.db ".EQU"
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; This is a list of handlers corresponding to indexes in directiveNames
directiveHandlers:
.dw handleDB
.dw handleDW
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.dw handleEQU
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handleDB:
push hl
call toWord
call readWord
ld hl, scratchpad
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call parseLiteral
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ld a, ixl
ld (direcData), a
ld a, 1
pop hl
ret
handleDW:
push hl
call toWord
call readWord
ld hl, scratchpad
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call parseExpr
ld a, ixl
ld (direcData), a
ld a, ixh
ld (direcData+1), a
ld a, 2
pop hl
ret
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handleEQU:
call zasmIsFirstPass
jr nz, .begin
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; first pass? .equ are noops
xor a
ret
.begin:
push hl
push de
push bc
; Read our constant name
call toWord
call readWord
; We can't register our symbol yet: we don't have our value!
; Let's copy it over.
push hl
ld hl, scratchpad
ld de, DIREC_SCRATCHPAD
ld bc, SCRATCHPAD_SIZE
ldir
pop hl
; Now, read the value associated to it
call toWord
call readWord
ld hl, scratchpad
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call parseExpr
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jr nz, .error
ld hl, DIREC_SCRATCHPAD
ld d, ixh
ld e, ixl
call symRegister
jr .end
.error:
.end:
xor a ; 0 bytes written
pop bc
pop de
pop hl
ret
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; Reads string in (HL) and returns the corresponding ID (D_*) in A. Sets Z if
; there's a match.
getDirectiveID:
push bc
push de
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ld b, D_EQU+1 ; D_EQU is last
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ld c, 4
ld de, directiveNames
call findStringInList
pop de
pop bc
ret
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; Parse directive specified in A (D_* const) with args in (HL) and act in
; an appropriate manner. If the directive results in writing data at its
; current location, that data is in (direcData) and A is the number of bytes
; in it.
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parseDirective:
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push de
; double A to have a proper offset in directiveHandlers
add a, a
ld de, directiveHandlers
call JUMP_ADDDE
call JUMP_INTODE
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ld ixh, d
ld ixl, e
pop de
jp (ix)
; *** Variables ***
direcData:
.fill 2