; 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 ; ( 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: call popRS ; We have a pointer to a word push hl \ pop iy jp compiledWord ; ( R:I -- ) QUIT: .db "QUIT", 0, 0, 0, 0 .dw EXIT .dw nativeWord quit: ld hl, FLAGS set FLAG_QUITTING, (hl) jp exit BYE: .db "BYE" .fill 5 .dw QUIT .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 jr nz, quit jr .loop .end: ; end chain with EXIT ld hl, EXIT+CODELINK_OFFSET ld (iy), l inc iy ld (iy), h inc iy ld (HERE), iy jp exit .issemicol: ld a, (hl) cp ';' ret nz inc hl ld a, (hl) dec hl or a ret ; ( -- c ) KEY: .db "KEY" .fill 5 .dw DEFINE .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 ; ( n -- ) DOT: .db "." .fill 7 .dw HERE_ .dw nativeWord pop de 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