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 NROT = defPrimWord("-ROT", () -> begin
254 ROT = defPrimWord("ROT", () -> begin
265 TWODROP = defPrimWord("2DROP", () -> begin
271 TWODUP = defPrimWord("2DUP", () -> begin
280 TWOSWAP = defPrimWord("2SWAP", () -> begin
292 QDUP = defPrimWord("?DUP", () -> begin
301 INCR = defPrimWord("1+", () -> begin
307 DECR = defPrimWord("1-", () -> begin
313 INCR2 = defPrimWord("2+", () -> begin
319 DECR2 = defPrimWord("2-", () -> begin
325 ADD = defPrimWord("+", () -> begin
332 SUB = defPrimWord("-", () -> begin
339 MUL = defPrimWord("*", () -> begin
346 DIVMOD = defPrimWord("/MOD", () -> begin
355 TWOMUL = defPrimWord("2*", () -> begin
360 TWODIV = defPrimWord("2/", () -> begin
365 EQU = defPrimWord("=", () -> begin
368 pushPS(a==b ? -1 : 0)
372 NEQU = defPrimWord("<>", () -> begin
375 pushPS(a!=b ? -1 : 0)
379 LT = defPrimWord("<", () -> begin
386 GT = defPrimWord(">", () -> begin
393 LE = defPrimWord("<=", () -> begin
396 pushPS(a<=b ? -1 : 0)
400 GE = defPrimWord(">=", () -> begin
403 pushPS(a>=b ? -1 : 0)
407 ZEQU = defPrimWord("0=", () -> begin
408 pushPS(popPS() == 0 ? -1 : 0)
412 ZNEQU = defPrimWord("0<>", () -> begin
413 pushPS(popPS() != 0 ? -1 : 0)
417 ZLT = defPrimWord("0<", () -> begin
418 pushPS(popPS() < 0 ? -1 : 0)
422 ZGT = defPrimWord("0>", () -> begin
423 pushPS(popPS() > 0 ? -1 : 0)
427 ZLE = defPrimWord("0<=", () -> begin
428 pushPS(popPS() <= 0 ? -1 : 0)
432 ZGE = defPrimWord("0>=", () -> begin
433 pushPS(popPS() >= 0 ? -1 : 0)
437 AND = defPrimWord("AND", () -> begin
444 OR = defPrimWord("OR", () -> begin
451 XOR = defPrimWord("XOR", () -> begin
458 INVERT = defPrimWord("INVERT", () -> begin
465 LIT = defPrimWord("LIT", () -> begin
473 STORE = defPrimWord("!", () -> begin
480 FETCH = defPrimWord("@", () -> begin
486 ADDSTORE = defPrimWord("+!", () -> begin
493 SUBSTORE = defPrimWord("-!", () -> begin
503 HERE_CFA = defExistingVar("HERE", HERE)
504 LATEST_CFA = defExistingVar("LATEST", LATEST)
505 PSP0_CFA = defExistingVar("PSP0", PSP0)
506 RSP0_CFA = defExistingVar("RSP0", RSP0)
507 STATE, STATE_CFA = defNewVar("STATE", 0)
508 BASE, BASE_CFA = defNewVar("BASE", 10)
512 defConst("VERSION", 1)
513 defConst("DOCOL", DOCOL)
514 defConst("DICT", DICT)
515 F_IMMED = defConst("F_IMMED", 128)
516 F_HIDDEN = defConst("F_HIDDEN", 256)
517 F_LENMASK = defConst("F_LENMASK", 127)
521 TOR = defPrimWord(">R", () -> begin
526 FROMR = defPrimWord("R>", () -> begin
531 RFETCH = defPrimWord("R@", () -> begin
536 RSPFETCH = defPrimWord("RSP@", () -> begin
541 RSPSTORE = defPrimWord("RSP!", () -> begin
546 RDROP = defPrimWord("RDROP", () -> begin
553 PSPFETCH = defPrimWord("PSP@", () -> begin
558 PSPSTORE = defPrimWord("PSP!", () -> begin
565 WFETCH = defPrimWord("W@", () -> begin
570 WSTORE = defPrimWord("W!", () -> begin
577 sources = Array{Any,1}()
578 currentSource() = sources[length(sources)]
581 NUMTIB, NUMTIB_CFA = defNewVar("#TIB", 0)
582 TOIN, TOIN_CFA = defNewVar(">IN", 0)
583 EOF = defConst("EOF", 4)
585 KEY = defPrimWord("KEY", () -> begin
586 if mem[TOIN] >= mem[NUMTIB]
589 if !eof(currentSource())
590 line = readline(currentSource())
591 mem[NUMTIB] = length(line)
599 pushPS(mem[TIB + mem[TOIN]])
605 EMIT = defPrimWord("EMIT", () -> begin
610 WORD = defPrimWord("WORD", () -> begin
627 if c == '\n' || c == eof_char
633 if c == ' ' || c == '\t'
643 if c == '\n' || c == eof_char
644 # Treat newline as a special word
646 mem[wordAddr + offset] = Int64(c)
653 mem[wordAddr + offset] = Int64(c)
659 if c == ' ' || c == '\t' || c == '\n' || c == eof_char
674 NUMBER = defPrimWord("NUMBER", () -> begin
679 s = getString(wordAddr, wordLen)
682 pushPS(parse(Int64, s, mem[BASE]))
685 pushPS(1) # Error indication
691 # Dictionary searches
693 FIND = defPrimWord("FIND", () -> begin
697 word = lowercase(getString(wordAddr, wordLen))
702 while (latest = mem[latest]) > 0
703 lenAndFlags = mem[latest+1]
704 len = lenAndFlags & F_LENMASK
705 hidden = (lenAndFlags & F_HIDDEN) == F_HIDDEN
707 if hidden || len != wordLen
712 thisWord = lowercase(getString(thisAddr, len))
714 if lowercase(thisWord) == lowercase(word)
724 TOCFA = defPrimWord(">CFA", () -> begin
727 lenAndFlags = mem[addr+1]
728 len = lenAndFlags & F_LENMASK
730 pushPS(addr + 2 + len)
735 TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
739 BRANCH = defPrimWord("BRANCH", () -> begin
740 reg.IP += mem[reg.IP]
744 ZBRANCH = defPrimWord("0BRANCH", () -> begin
746 reg.IP += mem[reg.IP]
756 CREATE = defPrimWord("CREATE", () -> begin
760 word = getString(wordAddr, wordLen)
762 createHeader(word, 0)
767 COMMA = defPrimWord(",", () -> begin
768 mem[mem[HERE]] = popPS()
774 LBRAC = defPrimWord("[", () -> begin
779 RBRAC = defPrimWord("]", () -> begin
784 HIDDEN = defPrimWord("HIDDEN", () -> begin
786 mem[addr] = mem[addr] $ F_HIDDEN
790 HIDE = defWord("HIDE",
800 LATEST_CFA, FETCH, HIDDEN,
804 SEMICOLON = defWord(";",
806 LATEST_CFA, FETCH, HIDDEN,
808 EXIT], flags=F_IMMED)
810 IMMEDIATE = defPrimWord("IMMEDIATE", () -> begin
811 lenAndFlagsAddr = mem[LATEST] + 1
812 mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
817 [STATE_CFA, FETCH, ZBRANCH, 7,
818 FROMR, DUP, INCR, TOR, FETCH, EXIT,
819 WORD, FIND, TOCFA, EXIT])
823 LITSTRING = defPrimWord("LITSTRING", () -> begin
833 TELL = defPrimWord("TELL", () -> begin
836 str = getString(addr, len)
843 EXECUTE = defPrimWord("EXECUTE", () -> begin
848 type ParseError <: Exception
849 wordName::ASCIIString
851 Base.showerror(io::IO, ex::ParseError) = print(io, "Parse error at word: '$(ex.wordName)'.")
853 DEBUG, DEBUG_CFA = defNewVar("DEBUG", 0)
855 INTERPRET = defPrimWord("INTERPRET", () -> begin
859 wordName = getString(mem[reg.PSP-1], mem[reg.PSP])
861 println("... ", replace(replace(wordName, "\004", "EOF"), "\n", "\\n"), " ...")
864 callPrim(mem[TWODUP])
867 wordAddr = mem[reg.PSP]
872 isImmediate = (mem[wordAddr+1] & F_IMMED) != 0
875 callPrim(mem[ROT]) # get rid of extra copy of word string details
879 if mem[STATE] == 0 || isImmediate
881 return callPrim(mem[EXECUTE])
883 # Append CFA to dictionary
887 # Not in dictionary, assume number
891 callPrim(mem[NUMBER])
894 throw(ParseError(wordName))
898 # Number already on stack!
900 # Append literal to dictionary
910 QUIT = defWord("QUIT",
915 BYE = defPrimWord("BYE", () -> begin
919 PROMPT = defPrimWord("PROMPT", () -> begin
923 NL = defPrimWord("\n", () -> begin
924 if mem[STATE] == 0 && currentSource() == STDIN
925 callPrim(mem[PROMPT])
930 INCLUDE = defPrimWord("INCLUDE", () -> begin
934 word = getString(wordAddr, wordLen)
936 push!(sources, open(word, "r"))
944 EOF_WORD = defPrimWord("\x04", () -> begin
945 if currentSource() != STDIN
946 close(currentSource())
952 if currentSource() == STDIN
953 callPrim(mem[PROMPT])
964 CHAR = defPrimWord("CHAR", () -> begin
968 word = getString(wordAddr, wordLen)
969 pushPS(Int64(word[1]))
975 initFileName = nothing
977 initFileName = "lib.4th"
978 elseif isfile(Pkg.dir("forth/src/lib.4th"))
979 initFileName = Pkg.dir("forth/src/lib.4th")
984 function run(;initialize=true)
985 # Begin with STDIN as source
986 push!(sources, STDIN)
988 global initialized, initFileName
989 if !initialized && initialize
990 if initFileName != nothing
991 print("Including definitions from $initFileName...")
992 push!(sources, open(initFileName, "r"))
995 println("No library file found. Only primitive words available.")
999 # Start with IP pointing to first instruction of outer interpreter
1002 # Primitive processing loop.
1003 # Everyting else is simply a consequence of this loop!
1008 println("Evaluating prim ", jmp," ", primNames[-jmp])
1014 showerror(STDOUT, ex)
1017 while !isempty(sources) && currentSource() != STDIN
1018 close(pop!(sources))
1031 function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
1032 chars = Array{Char,1}(cellsPerLine)
1034 lineStartAddr = cellsPerLine*div((startAddr-1),cellsPerLine) + 1
1035 endAddr = startAddr + count - 1
1037 q, r = divrem((endAddr-lineStartAddr+1), cellsPerLine)
1038 numLines = q + (r > 0 ? 1 : 0)
1044 for c in 1:cellsPerLine
1045 if i >= startAddr && i <= endAddr
1047 if mem[i]>=32 && mem[i]<128
1048 chars[c] = Char(mem[i])
1060 println("\t", ASCIIString(chars))
1065 count = reg.PSP - mem[PSP0]
1069 for i in (mem[PSP0]+1):reg.PSP
1074 println("Parameter stack empty")
1079 count = reg.RSP - mem[RSP0]
1083 for i in (mem[RSP0]+1):reg.RSP
1088 println("Return stack empty")
1092 DUMP = defPrimWord("DUMP", () -> begin
1096 dump(addr, count=count)