7 size_RS = 1024 # Return stack size
8 size_PS = 1024 # Parameter stack size
9 size_TIB = 1096 # Terminal input buffer size
11 # The mem array constitutes the memory of the VM. It has the following geography:
13 # mem = +-----------------------+
14 # | Built-in Variables |
15 # +-----------------------+
17 # +-----------------------+
19 # +-----------------------+
20 # | Terminal Input Buffer |
21 # +-----------------------+
23 # +-----------------------+
25 # Note that all words (user-defined, primitive, variables, etc) are included in
28 # Simple linear addressing is used with one exception: references to primitive code
29 # blocks, which are represented as anonymous functions, appear as negative indicies
30 # into the primitives array which contains these functions.
32 mem = Array{Int64,1}(size_mem)
33 primitives = Array{Function,1}()
34 primNames = Array{ASCIIString,1}()
39 RSP0 = nextVarAddr; nextVarAddr += 1
40 PSP0 = nextVarAddr; nextVarAddr += 1
41 HERE = nextVarAddr; nextVarAddr += 1
42 LATEST = nextVarAddr; nextVarAddr += 1
44 mem[RSP0] = nextVarAddr # bottom of RS
45 mem[PSP0] = mem[RSP0] + size_RS # bottom of PS
46 TIB = mem[PSP0] + size_PS # address of terminal input buffer
47 mem[HERE] = TIB + size_TIB # location of bottom of dictionary
48 mem[LATEST] = 0 # no previous definition
50 DICT = mem[HERE] # Save bottom of dictionary as constant
54 RSP::Int64 # Return stack pointer
55 PSP::Int64 # Parameter/data stack pointer
56 IP::Int64 # Instruction pointer
57 W::Int64 # Working register
59 reg = Reg(mem[RSP0], mem[PSP0], 0, 0)
61 # Stack manipulation functions
63 type ParamStackUnderflow <: Exception end
64 type ReturnStackUnderflow <: Exception end
66 Base.showerror(io::IO, ex::ParamStackUnderflow) = print(io, "Parameter stack underflow.")
67 Base.showerror(io::IO, ex::ReturnStackUnderflow) = print(io, "Return stack underflow.")
69 getRSDepth() = reg.RSP - mem[RSP0]
70 getPSDepth() = reg.PSP - mem[PSP0]
72 function ensurePSDepth(depth::Int64)
74 throw(ParamStackUnderflow())
78 function ensureRSDepth(depth::Int64)
80 throw(ReturnStackUnderflow())
84 function pushRS(val::Int64)
96 function pushPS(val::Int64)
97 mem[reg.PSP += 1] = val
108 # Handy functions for adding/retrieving strings to/from memory.
110 getString(addr::Int64, len::Int64) = ASCIIString([Char(c) for c in mem[addr:(addr+len-1)]])
111 function putString(str::ASCIIString, addr::Int64)
112 mem[addr:(addr+length(str)-1)] = [Int64(c) for c in str]
115 # Primitive creation and calling functions
117 function defPrim(f::Function; name="nameless")
119 push!(primNames, replace(replace(name, "\004", "EOF"), "\n", "\\n"))
121 return -length(primitives)
124 callPrim(addr::Int64) = primitives[-addr]()
128 function createHeader(name::AbstractString, flags::Int64)
129 mem[mem[HERE]] = mem[LATEST]
130 mem[LATEST] = mem[HERE]
133 mem[mem[HERE]] = length(name) | flags; mem[HERE] += 1
134 putString(name, mem[HERE]); mem[HERE] += length(name)
137 function defPrimWord(name::AbstractString, f::Function; flags::Int64=0)
138 createHeader(name, flags)
140 codeWordAddr = mem[HERE]
141 mem[codeWordAddr] = defPrim(f, name=name)
147 function defWord(name::AbstractString, wordAddrs::Array{Int64,1}; flags::Int64=0)
148 createHeader(name, flags)
151 mem[mem[HERE]] = DOCOL
154 for wordAddr in wordAddrs
155 mem[mem[HERE]] = wordAddr
164 function defExistingVar(name::AbstractString, varAddr::Int64; flags::Int64=0)
166 defPrimWord(name, eval(:(() -> begin
172 function defNewVar(name::AbstractString, initial::Int64; flags::Int64=0)
173 createHeader(name, flags)
175 codeWordAddr = mem[HERE]
176 varAddr = mem[HERE] + 1
178 f = eval(:(() -> begin
183 mem[mem[HERE]] = defPrim(f, name=name); mem[HERE] += 1
184 mem[mem[HERE]] = initial; mem[HERE] += 1
186 return varAddr, codeWordAddr
189 function defConst(name::AbstractString, val::Int64; flags::Int64=0)
190 defPrimWord(name, eval(:(() -> begin
198 # Threading Primitives (inner interpreter)
200 NEXT = defPrim(() -> begin
206 DOCOL = defPrim(() -> begin
212 EXIT = defPrimWord("EXIT", () -> begin
217 # Basic forth primitives
219 DROP = defPrimWord("DROP", () -> begin
224 SWAP = defPrimWord("SWAP", () -> begin
232 DUP = defPrimWord("DUP", () -> begin
238 OVER = defPrimWord("OVER", () -> begin
240 pushPS(mem[reg.PSP-1])
244 ROT = defPrimWord("ROT", () -> begin
254 NROT = defPrimWord("-ROT", () -> begin
265 TWODROP = defPrimWord("2DROP", () -> begin
271 TWODUP = defPrimWord("2DUP", () -> begin
280 TWOSWAP = defPrimWord("2SWAP", () -> begin
292 TWOOVER = defPrimWord("2OVER", () -> begin
301 QDUP = defPrimWord("?DUP", () -> begin
310 INCR = defPrimWord("1+", () -> begin
316 DECR = defPrimWord("1-", () -> begin
322 INCR2 = defPrimWord("2+", () -> begin
328 DECR2 = defPrimWord("2-", () -> begin
334 ADD = defPrimWord("+", () -> begin
341 SUB = defPrimWord("-", () -> begin
348 MUL = defPrimWord("*", () -> begin
355 DIVMOD = defPrimWord("/MOD", () -> begin
364 TWOMUL = defPrimWord("2*", () -> begin
369 TWODIV = defPrimWord("2/", () -> begin
374 EQU = defPrimWord("=", () -> begin
377 pushPS(a==b ? -1 : 0)
381 NEQU = defPrimWord("<>", () -> begin
384 pushPS(a!=b ? -1 : 0)
388 LT = defPrimWord("<", () -> begin
395 GT = defPrimWord(">", () -> begin
402 LE = defPrimWord("<=", () -> begin
405 pushPS(a<=b ? -1 : 0)
409 GE = defPrimWord(">=", () -> begin
412 pushPS(a>=b ? -1 : 0)
416 ZEQU = defPrimWord("0=", () -> begin
417 pushPS(popPS() == 0 ? -1 : 0)
421 ZNEQU = defPrimWord("0<>", () -> begin
422 pushPS(popPS() != 0 ? -1 : 0)
426 ZLT = defPrimWord("0<", () -> begin
427 pushPS(popPS() < 0 ? -1 : 0)
431 ZGT = defPrimWord("0>", () -> begin
432 pushPS(popPS() > 0 ? -1 : 0)
436 ZLE = defPrimWord("0<=", () -> begin
437 pushPS(popPS() <= 0 ? -1 : 0)
441 ZGE = defPrimWord("0>=", () -> begin
442 pushPS(popPS() >= 0 ? -1 : 0)
446 AND = defPrimWord("AND", () -> begin
453 OR = defPrimWord("OR", () -> begin
460 XOR = defPrimWord("XOR", () -> begin
467 INVERT = defPrimWord("INVERT", () -> begin
474 LIT = defPrimWord("LIT", () -> begin
482 STORE = defPrimWord("!", () -> begin
489 FETCH = defPrimWord("@", () -> begin
495 ADDSTORE = defPrimWord("+!", () -> begin
502 SUBSTORE = defPrimWord("-!", () -> begin
512 HERE_CFA = defExistingVar("HERE", HERE)
513 LATEST_CFA = defExistingVar("LATEST", LATEST)
514 PSP0_CFA = defExistingVar("PSP0", PSP0)
515 RSP0_CFA = defExistingVar("RSP0", RSP0)
516 STATE, STATE_CFA = defNewVar("STATE", 0)
517 BASE, BASE_CFA = defNewVar("BASE", 10)
521 defConst("VERSION", 1)
522 defConst("DOCOL", DOCOL)
523 defConst("DICT", DICT)
524 F_IMMED = defConst("F_IMMED", 128)
525 F_HIDDEN = defConst("F_HIDDEN", 256)
526 F_LENMASK = defConst("F_LENMASK", 127)
530 TOR = defPrimWord(">R", () -> begin
535 FROMR = defPrimWord("R>", () -> begin
540 RFETCH = defPrimWord("R@", () -> begin
545 RSPFETCH = defPrimWord("RSP@", () -> begin
550 RSPSTORE = defPrimWord("RSP!", () -> begin
555 RDROP = defPrimWord("RDROP", () -> begin
562 PSPFETCH = defPrimWord("PSP@", () -> begin
567 PSPSTORE = defPrimWord("PSP!", () -> begin
574 WFETCH = defPrimWord("W@", () -> begin
579 WSTORE = defPrimWord("W!", () -> begin
586 sources = Array{Any,1}()
587 currentSource() = sources[length(sources)]
590 NUMTIB, NUMTIB_CFA = defNewVar("#TIB", 0)
591 TOIN, TOIN_CFA = defNewVar(">IN", 0)
592 EOF = defConst("EOF", 4)
594 KEY = defPrimWord("KEY", () -> begin
595 if mem[TOIN] >= mem[NUMTIB]
598 if !eof(currentSource())
599 line = readline(currentSource())
600 mem[NUMTIB] = length(line)
608 pushPS(mem[TIB + mem[TOIN]])
614 EMIT = defPrimWord("EMIT", () -> begin
619 WORD = defPrimWord("WORD", () -> begin
636 if c == '\n' || c == eof_char
642 if c == ' ' || c == '\t'
652 if c == '\n' || c == eof_char
653 # Treat newline as a special word
655 mem[wordAddr + offset] = Int64(c)
662 mem[wordAddr + offset] = Int64(c)
668 if c == ' ' || c == '\t' || c == '\n' || c == eof_char
683 NUMBER = defPrimWord("NUMBER", () -> begin
688 s = getString(wordAddr, wordLen)
691 pushPS(parse(Int64, s, mem[BASE]))
694 pushPS(1) # Error indication
700 # Dictionary searches
702 FIND = defPrimWord("FIND", () -> begin
706 word = lowercase(getString(wordAddr, wordLen))
711 while (latest = mem[latest]) > 0
712 lenAndFlags = mem[latest+1]
713 len = lenAndFlags & F_LENMASK
714 hidden = (lenAndFlags & F_HIDDEN) == F_HIDDEN
716 if hidden || len != wordLen
721 thisWord = lowercase(getString(thisAddr, len))
723 if lowercase(thisWord) == lowercase(word)
733 TOCFA = defPrimWord(">CFA", () -> begin
736 lenAndFlags = mem[addr+1]
737 len = lenAndFlags & F_LENMASK
739 pushPS(addr + 2 + len)
744 TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
748 BRANCH = defPrimWord("BRANCH", () -> begin
749 reg.IP += mem[reg.IP]
753 ZBRANCH = defPrimWord("0BRANCH", () -> begin
755 reg.IP += mem[reg.IP]
765 CREATE = defPrimWord("CREATE", () -> begin
769 word = getString(wordAddr, wordLen)
771 createHeader(word, 0)
776 COMMA = defPrimWord(",", () -> begin
777 mem[mem[HERE]] = popPS()
783 LBRAC = defPrimWord("[", () -> begin
788 RBRAC = defPrimWord("]", () -> begin
793 HIDDEN = defPrimWord("HIDDEN", () -> begin
795 mem[addr] = mem[addr] $ F_HIDDEN
799 HIDE = defWord("HIDE",
809 LATEST_CFA, FETCH, HIDDEN,
813 SEMICOLON = defWord(";",
815 LATEST_CFA, FETCH, HIDDEN,
817 EXIT], flags=F_IMMED)
819 IMMEDIATE = defPrimWord("IMMEDIATE", () -> begin
820 lenAndFlagsAddr = mem[LATEST] + 1
821 mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
826 [STATE_CFA, FETCH, ZBRANCH, 7,
827 FROMR, DUP, INCR, TOR, FETCH, EXIT,
828 WORD, FIND, TOCFA, EXIT])
832 LITSTRING = defPrimWord("LITSTRING", () -> begin
842 TELL = defPrimWord("TELL", () -> begin
845 str = getString(addr, len)
852 EXECUTE = defPrimWord("EXECUTE", () -> begin
857 type ParseError <: Exception
858 wordName::ASCIIString
860 Base.showerror(io::IO, ex::ParseError) = print(io, "Parse error at word: '$(ex.wordName)'.")
862 DEBUG, DEBUG_CFA = defNewVar("DEBUG", 0)
864 INTERPRET = defPrimWord("INTERPRET", () -> begin
868 wordName = getString(mem[reg.PSP-1], mem[reg.PSP])
870 println("... ", replace(replace(wordName, "\004", "EOF"), "\n", "\\n"), " ...")
873 callPrim(mem[TWODUP])
876 wordAddr = mem[reg.PSP]
881 isImmediate = (mem[wordAddr+1] & F_IMMED) != 0
884 callPrim(mem[NROT]) # get rid of extra copy of word string details
888 if mem[STATE] == 0 || isImmediate
890 return callPrim(mem[EXECUTE])
892 # Append CFA to dictionary
896 # Not in dictionary, assume number
900 callPrim(mem[NUMBER])
903 throw(ParseError(wordName))
907 # Number already on stack!
909 # Append literal to dictionary
919 QUIT = defWord("QUIT",
924 BYE = defPrimWord("BYE", () -> begin
928 PROMPT = defPrimWord("PROMPT", () -> begin
932 NL = defPrimWord("\n", () -> begin
933 if mem[STATE] == 0 && currentSource() == STDIN
934 callPrim(mem[PROMPT])
939 INCLUDE = defPrimWord("INCLUDE", () -> begin
943 word = getString(wordAddr, wordLen)
945 push!(sources, open(word, "r"))
953 EOF_WORD = defPrimWord("\x04", () -> begin
954 if currentSource() != STDIN
955 close(currentSource())
961 if currentSource() == STDIN
962 callPrim(mem[PROMPT])
973 CHAR = defPrimWord("CHAR", () -> begin
977 word = getString(wordAddr, wordLen)
978 pushPS(Int64(word[1]))
984 initFileName = nothing
986 initFileName = "lib.4th"
987 elseif isfile(Pkg.dir("forth/src/lib.4th"))
988 initFileName = Pkg.dir("forth/src/lib.4th")
993 function run(;initialize=true)
994 # Begin with STDIN as source
995 push!(sources, STDIN)
997 global initialized, initFileName
998 if !initialized && initialize
999 if initFileName != nothing
1000 print("Including definitions from $initFileName...")
1001 push!(sources, open(initFileName, "r"))
1004 println("No library file found. Only primitive words available.")
1008 # Start with IP pointing to first instruction of outer interpreter
1011 # Primitive processing loop.
1012 # Everyting else is simply a consequence of this loop!
1017 println("Evaluating prim ", jmp," ", primNames[-jmp])
1023 showerror(STDOUT, ex)
1026 while !isempty(sources) && currentSource() != STDIN
1027 close(pop!(sources))
1042 function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
1043 chars = Array{Char,1}(cellsPerLine)
1045 lineStartAddr = cellsPerLine*div((startAddr-1),cellsPerLine) + 1
1046 endAddr = startAddr + count - 1
1048 q, r = divrem((endAddr-lineStartAddr+1), cellsPerLine)
1049 numLines = q + (r > 0 ? 1 : 0)
1055 for c in 1:cellsPerLine
1056 if i >= startAddr && i <= endAddr
1058 if mem[i]>=32 && mem[i]<128
1059 chars[c] = Char(mem[i])
1071 println("\t", ASCIIString(chars))
1076 count = reg.PSP - mem[PSP0]
1080 for i in (mem[PSP0]+1):reg.PSP
1085 println("Parameter stack empty")
1090 count = reg.RSP - mem[RSP0]
1094 for i in (mem[RSP0]+1):reg.RSP
1099 println("Return stack empty")
1103 DUMP = defPrimWord("DUMP", () -> begin
1107 dump(addr, count=count)