collapseos/apps/forth/dict.asm

447 lines
7.1 KiB
NASM

; A dictionary entry has this structure:
; - 8b name (zero-padded)
; - 2b prev pointer
; - 2b code pointer
; - Parameter field (PF)
;
; The code pointer point to "word routines". These routines expect to be called
; with IY pointing to the PF. They themselves are expected to end by jumping
; to the address at the top of the Return Stack. They will usually do so with
; "jp exit".
; Execute a word containing native code at its PF address (PFA)
nativeWord:
jp (iy)
; Execute a compiled word containing a list of references to other words,
; usually ended by a reference to EXIT.
; A reference to a word in a compiledWord section is *not* a direct reference,
; but a word+CODELINK_OFFSET reference. Therefore, for a code link "link",
; (link) is the routine to call.
compiledWord:
push iy \ pop hl
inc hl
inc hl
; HL points to next Interpreter pointer.
call pushRS
ld l, (iy)
ld h, (iy+1)
push hl \ pop iy
; IY points to code link
jp executeCodeLink
; Pushes the PFA directly
cellWord:
push iy
jp exit
; Pushes the address in the first word of the PF
sysvarWord:
ld l, (iy)
ld h, (iy+1)
push hl
jp exit
; The word was spawned from a definition word that has a DOES>. PFA+2 (right
; after the actual cell) is a link to the slot right after that DOES>.
; Therefore, what we need to do push the cell addr like a regular cell, then
; follow the link from the PFA, and then continue as a regular compiledWord.
doesWord:
push iy ; like a regular cell
ld l, (iy+2)
ld h, (iy+3)
push hl \ pop iy
jr compiledWord
; This is not a word, but a number literal. This works a bit differently than
; others: PF means nothing and the actual number is placed next to the
; numberWord reference in the compiled word list. What we need to do to fetch
; that number is to play with the Return stack: We pop it, read the number, push
; it to the Parameter stack and then push an increase Interpreter Pointer back
; to RS.
numberWord:
call popRS
ld e, (hl)
inc hl
ld d, (hl)
inc hl
call pushRS
push de
jp exit
NUMBER:
.dw numberWord
; ( R:I -- )
EXIT:
.db "EXIT", 0, 0, 0, 0
.dw 0
.dw nativeWord
; When we call the EXIT word, we have to do a "double exit" because our current
; Interpreter pointer is pointing to the word *next* to our EXIT reference when,
; in fact, we want to continue processing the one above it.
call popRS
exit:
; Before we continue: is SP within bounds?
call chkPS
; we're good
call popRS
; We have a pointer to a word
push hl \ pop iy
jr compiledWord
; ( R:I -- )
QUIT:
.db "QUIT", 0, 0, 0, 0
.dw EXIT
.dw nativeWord
quit:
ld hl, FLAGS
set FLAG_QUITTING, (hl)
jr exit
ABORT:
.db "ABORT", 0, 0, 0
.dw QUIT
.dw nativeWord
abort:
ld sp, (INITIAL_SP)
ld hl, .msg
call printstr
call printcrlf
jr quit
.msg:
.db " err", 0
BYE:
.db "BYE"
.fill 5
.dw ABORT
.dw nativeWord
ld hl, FLAGS
set FLAG_ENDPGM, (hl)
jp exit
; ( c -- )
EMIT:
.db "EMIT", 0, 0, 0, 0
.dw BYE
.dw nativeWord
pop hl
ld a, l
call stdioPutC
jp exit
; ( addr -- )
EXECUTE:
.db "EXECUTE", 0
.dw EMIT
.dw nativeWord
pop iy ; Points to word_offset
ld de, CODELINK_OFFSET
add iy, de
executeCodeLink:
ld l, (iy)
ld h, (iy+1)
; HL points to code pointer
inc iy
inc iy
; IY points to PFA
jp (hl) ; go!
DEFINE:
.db ":"
.fill 7
.dw EXECUTE
.dw nativeWord
call entryhead
jp nz, quit
ld de, compiledWord
ld (hl), e
inc hl
ld (hl), d
inc hl
push hl \ pop iy
.loop:
call readword
jr nz, .end
call .issemicol
jr z, .end
call compile
jp nz, quit
jr .loop
.end:
; end chain with EXIT
ld hl, EXIT+CODELINK_OFFSET
call wrCompHL
ld (HERE), iy
jp exit
.issemicol:
ld a, (hl)
cp ';'
ret nz
inc hl
ld a, (hl)
dec hl
or a
ret
DOES:
.db "DOES>", 0, 0, 0
.dw DEFINE
.dw nativeWord
; We run this when we're in an entry creation context. Many things we
; need to do.
; 1. Change the code link to doesWord
; 2. Leave 2 bytes for regular cell variable.
; 3. Get the Interpreter pointer from the stack and write this down to
; entry PFA+2.
; 3. exit. Because we've already popped RS, a regular exit will abort
; colon definition, so we're good.
ld iy, (CURRENT)
ld de, CODELINK_OFFSET
add iy, de
ld hl, doesWord
call wrCompHL
inc iy \ inc iy ; cell variable space
call popRS
call wrCompHL
ld (HERE), iy
jp exit
; ( -- c )
KEY:
.db "KEY"
.fill 5
.dw DOES
.dw nativeWord
call stdioGetC
ld h, 0
ld l, a
push hl
jp exit
INTERPRET:
.db "INTERPRE"
.dw KEY
.dw nativeWord
interpret:
call readword
jp nz, quit
ld iy, COMPBUF
call compile
jp nz, .notfound
ld hl, EXIT+CODELINK_OFFSET
ld (iy), l
ld (iy+1), h
ld iy, COMPBUF
jp compiledWord
.notfound:
ld hl, .msg
call printstr
jp quit
.msg:
.db "not found", 0
CREATE:
.db "CREATE", 0, 0
.dw INTERPRET
.dw nativeWord
call entryhead
jp nz, quit
ld de, cellWord
ld (hl), e
inc hl
ld (hl), d
inc hl
ld (HERE), hl
jp exit
HERE_: ; Caution: conflicts with actual variable name
.db "HERE"
.fill 4
.dw CREATE
.dw sysvarWord
.dw HERE
CURRENT_:
.db "CURRENT", 0
.dw HERE_
.dw sysvarWord
.dw CURRENT
; ( n -- )
DOT:
.db "."
.fill 7
.dw CURRENT_
.dw nativeWord
pop de
; We check PS explicitly because it doesn't look nice to spew gibberish
; before aborting the stack underflow.
call chkPS
call pad
call fmtDecimalS
call printstr
jp exit
; ( n a -- )
STORE:
.db "!"
.fill 7
.dw DOT
.dw nativeWord
pop iy
pop hl
ld (iy), l
ld (iy+1), h
jp exit
; ( a -- n )
FETCH:
.db "@"
.fill 7
.dw STORE
.dw nativeWord
pop hl
call intoHL
push hl
jp exit
; ( a b -- b a )
SWAP:
.db "SWAP"
.fill 4
.dw FETCH
.dw nativeWord
pop hl
ex (sp), hl
push hl
jp exit
; ( a -- a a )
DUP:
.db "DUP"
.fill 5
.dw SWAP
.dw nativeWord
pop hl
push hl
push hl
jp exit
; ( a b -- a b a )
OVER:
.db "OVER"
.fill 4
.dw DUP
.dw nativeWord
pop hl ; B
pop de ; A
push de
push hl
push de
jp exit
; ( a b -- c ) A + B
PLUS:
.db "+"
.fill 7
.dw OVER
.dw nativeWord
pop hl
pop de
add hl, de
push hl
jp exit
; ( a b -- c ) A - B
MINUS:
.db "-"
.fill 7
.dw PLUS
.dw nativeWord
pop de ; B
pop hl ; A
or a ; reset carry
sbc hl, de
push hl
jp exit
; ( a b -- c ) A * B
MULT:
.db "*"
.fill 7
.dw MINUS
.dw nativeWord
pop de
pop bc
call multDEBC
push hl
jp exit
; ( a b -- c ) A / B
DIV:
.db "/"
.fill 7
.dw MULT
.dw nativeWord
pop de
pop hl
call divide
push bc
jp exit
; End of native words
; ( a -- )
; @ .
FETCHDOT:
.db "?"
.fill 7
.dw DIV
.dw compiledWord
.dw FETCH+CODELINK_OFFSET
.dw DOT+CODELINK_OFFSET
.dw EXIT+CODELINK_OFFSET
; ( n a -- )
; SWAP OVER @ + SWAP !
STOREINC:
.db "+!"
.fill 6
.dw FETCHDOT
.dw compiledWord
.dw SWAP+CODELINK_OFFSET
.dw OVER+CODELINK_OFFSET
.dw FETCH+CODELINK_OFFSET
.dw PLUS+CODELINK_OFFSET
.dw SWAP+CODELINK_OFFSET
.dw STORE+CODELINK_OFFSET
.dw EXIT+CODELINK_OFFSET
; ( n -- )
; HERE +!
ALLOT:
.db "ALLOT", 0, 0, 0
.dw STOREINC
.dw compiledWord
.dw HERE_+CODELINK_OFFSET
.dw STOREINC+CODELINK_OFFSET
.dw EXIT+CODELINK_OFFSET
; ( n -- )
; CREATE HERE @ ! DOES> @
CONSTANT:
.db "CONSTANT"
.dw ALLOT
.dw compiledWord
.dw CREATE+CODELINK_OFFSET
.dw HERE_+CODELINK_OFFSET
.dw FETCH+CODELINK_OFFSET
.dw STORE+CODELINK_OFFSET
.dw DOES+CODELINK_OFFSET
.dw FETCH+CODELINK_OFFSET
.dw EXIT+CODELINK_OFFSET