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111 lines
2.1 KiB
NASM
111 lines
2.1 KiB
NASM
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; A dictionary entry has this structure:
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; - 8b name (zero-padded)
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; - 2b prev pointer
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; - 2b code pointer
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; - Parameter field area (PFA)
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;
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; The code pointer point to "word routines". These routines expect to be called
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; with IY pointing to the PFA. They themselves are expected to end by jumping
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; to the address at the top of the Return Stack. They will usually do so with
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; "jp exit".
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; Execute a word containing native code at its PFA
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nativeWord:
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jp (iy)
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; Execute a compiled word containing a list of references to other words,
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; usually ended by a reference to EXIT.
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; A reference to a word in a compiledWord section is *not* a direct reference,
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; but a word+CODELINK_OFFSET reference. Therefore, for a code link "link",
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; (link) is the routine to call.
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compiledWord:
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push iy \ pop hl
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inc hl
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inc hl
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; HL points to next Interpreter pointer.
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call pushRS
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ld l, (iy)
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ld h, (iy+1)
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push hl \ pop iy
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; IY points to code link
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jp executeCodeLink
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; ( R:I -- )
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EXIT:
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.db "EXIT", 0, 0, 0, 0
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.dw 0
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.dw nativeWord
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; When we call the EXIT word, we have to do a "double exit" because our current
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; Interpreter pointer is pointing to the word *next* to our EXIT reference when,
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; in fact, we want to continue processing the one above it.
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call popRS
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exit:
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call popRS
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; We have a pointer to a word
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push hl \ pop iy
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jp compiledWord
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; ( c -- )
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EMIT:
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.db "EMIT", 0, 0, 0, 0
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.dw EXIT
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.dw nativeWord
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pop hl
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ld a, l
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call stdioPutC
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jp exit
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; ( addr -- )
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EXECUTE:
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.db "EXECUTE", 0
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.dw EMIT
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.dw nativeWord
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pop iy ; Points to word_offset
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ld de, CODELINK_OFFSET
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add iy, de
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executeCodeLink:
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ld l, (iy)
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ld h, (iy+1)
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; HL points to code pointer
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inc iy
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inc iy
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; IY points to PFA
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jp (hl) ; go!
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; ( -- c )
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KEY:
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.db "KEY", 0, 0, 0, 0, 0
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.dw EXECUTE
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.dw nativeWord
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call stdioGetC
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ld h, 0
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ld l, a
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push hl
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jp exit
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INTERPRET:
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.db "INTERPRE"
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.dw KEY
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.dw nativeWord
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call pad
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push hl \ pop iy
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call stdioReadLine
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ld (INPUTPOS), hl
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.loop:
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call readword
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jp nz, .loopend
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call compile
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jr nz, .notfound
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jr .loop
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.loopend:
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call compileExit
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call pad
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push hl \ pop iy
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jp compiledWord
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.notfound:
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ld hl, .msg
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call printstr
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jp exit
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.msg:
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.db "not found", 0
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