collapseos/apps/zasm/directive.asm
2019-05-16 21:15:00 -04:00

148 lines
2.5 KiB
NASM

; *** CONSTS ***
.equ D_DB 0x00
.equ D_DW 0x01
.equ D_EQU 0x02
.equ D_INC 0x03
.equ D_BAD 0xff
; *** Variables ***
.equ DIREC_SCRATCHPAD DIREC_RAMSTART
.equ DIREC_RAMEND DIREC_SCRATCHPAD+SCRATCHPAD_SIZE
; *** CODE ***
; 4 bytes per row, fill with zero
directiveNames:
.db ".DB", 0
.db ".DW", 0
.db ".EQU"
.db "#inc"
; This is a list of handlers corresponding to indexes in directiveNames
directiveHandlers:
.dw handleDB
.dw handleDW
.dw handleEQU
.dw handleINC
handleDB:
push hl
call readWord
ld hl, scratchpad
call parseLiteral
ld a, ixl
ld (direcData), a
ld a, 1
pop hl
ret
handleDW:
push hl
call readWord
ld hl, scratchpad
call parseExpr
ld a, ixl
ld (direcData), a
ld a, ixh
ld (direcData+1), a
ld a, 2
pop hl
ret
handleEQU:
call zasmIsFirstPass
jr nz, .begin
; first pass? .equ are noops Consume args and return
call readWord
call readWord
xor a
ret
.begin:
push hl
push de
push bc
; Read our constant name
call readWord
; We can't register our symbol yet: we don't have our value!
; Let's copy it over.
ld de, DIREC_SCRATCHPAD
ld bc, SCRATCHPAD_SIZE
ldir
; Now, read the value associated to it
call readWord
ld hl, scratchpad
call parseExpr
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
handleINC:
call readWord
jr nz, .end
; HL points to scratchpad
; First, let's verify that our string is enquoted
ld a, (hl)
cp '"'
jr nz, .end
; We have opening quote
inc hl
xor a
call JUMP_FINDCHAR ; go to end of string
dec hl
ld a, (hl)
cp '"'
jr nz, .end
; we have ending quote, let's replace with null char
xor a
ld (hl), a
; Good, let's go back
ld hl, scratchpad+1 ; +1 because of the opening quote
call ioOpenInclude
.end:
xor a ; zero bytes written
ret
; Reads string in (HL) and returns the corresponding ID (D_*) in A. Sets Z if
; there's a match.
getDirectiveID:
push bc
push de
ld b, D_INC+1 ; D_INC is last
ld c, 4
ld de, directiveNames
call findStringInList
pop de
pop bc
ret
; Parse directive specified in A (D_* const) with args in I/O 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.
parseDirective:
push de
; double A to have a proper offset in directiveHandlers
add a, a
ld de, directiveHandlers
call JUMP_ADDDE
call JUMP_INTODE
ld ixh, d
ld ixl, e
pop de
jp (ix)
; *** Variables ***
direcData:
.fill 2