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]()
126 # Word creation functions
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
162 # Variable creation functions
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 mem[mem[HERE]] = DOVAR; mem[HERE] += 1
179 mem[mem[HERE]] = initial; mem[HERE] += 1
181 return varAddr, codeWordAddr
184 function defConst(name::AbstractString, val::Int64; flags::Int64=0)
185 createHeader(name, flags)
187 mem[mem[HERE]] = DOCON; mem[HERE] += 1
188 mem[mem[HERE]] = val; mem[HERE] += 1
193 # Threading Primitives (inner interpreter)
195 NEXT = defPrim(() -> begin
201 DOCOL = defPrim(() -> begin
207 DOVAR = defPrim(() -> begin
212 DOCON = defPrim(() -> begin
213 pushPS(mem[reg.W + 1])
217 EXIT = defPrimWord("EXIT", () -> begin
222 # Dictionary entries for core built-in variables, constants
224 HERE_CFA = defExistingVar("HERE", HERE)
225 LATEST_CFA = defExistingVar("LATEST", LATEST)
226 PSP0_CFA = defExistingVar("PSP0", PSP0)
227 RSP0_CFA = defExistingVar("RSP0", RSP0)
229 defConst("DOCOL", DOCOL)
230 defConst("DOCON", DOCON)
231 defConst("DOVAR", DOVAR)
233 defConst("DICT", DICT)
235 F_IMMED = defConst("F_IMMED", 128)
236 F_HIDDEN = defConst("F_HIDDEN", 256)
237 F_LENMASK = defConst("F_LENMASK", 127)
241 # Basic forth primitives
243 DROP = defPrimWord("DROP", () -> begin
248 SWAP = defPrimWord("SWAP", () -> begin
256 DUP = defPrimWord("DUP", () -> begin
262 OVER = defPrimWord("OVER", () -> begin
264 pushPS(mem[reg.PSP-1])
268 ROT = defPrimWord("ROT", () -> begin
278 NROT = defPrimWord("-ROT", () -> begin
289 TWODROP = defPrimWord("2DROP", () -> begin
295 TWODUP = defPrimWord("2DUP", () -> begin
304 TWOSWAP = defPrimWord("2SWAP", () -> begin
316 TWOOVER = defPrimWord("2OVER", () -> begin
325 QDUP = defPrimWord("?DUP", () -> begin
334 INCR = defPrimWord("1+", () -> begin
340 DECR = defPrimWord("1-", () -> begin
346 INCR2 = defPrimWord("2+", () -> begin
352 DECR2 = defPrimWord("2-", () -> begin
358 ADD = defPrimWord("+", () -> begin
365 SUB = defPrimWord("-", () -> begin
372 MUL = defPrimWord("*", () -> begin
379 DIVMOD = defPrimWord("/MOD", () -> begin
388 TWOMUL = defPrimWord("2*", () -> begin
393 TWODIV = defPrimWord("2/", () -> begin
398 EQU = defPrimWord("=", () -> begin
401 pushPS(a==b ? -1 : 0)
405 NEQU = defPrimWord("<>", () -> begin
408 pushPS(a!=b ? -1 : 0)
412 LT = defPrimWord("<", () -> begin
419 GT = defPrimWord(">", () -> begin
426 LE = defPrimWord("<=", () -> begin
429 pushPS(a<=b ? -1 : 0)
433 GE = defPrimWord(">=", () -> begin
436 pushPS(a>=b ? -1 : 0)
440 ZEQU = defPrimWord("0=", () -> begin
441 pushPS(popPS() == 0 ? -1 : 0)
445 ZNEQU = defPrimWord("0<>", () -> begin
446 pushPS(popPS() != 0 ? -1 : 0)
450 ZLT = defPrimWord("0<", () -> begin
451 pushPS(popPS() < 0 ? -1 : 0)
455 ZGT = defPrimWord("0>", () -> begin
456 pushPS(popPS() > 0 ? -1 : 0)
460 ZLE = defPrimWord("0<=", () -> begin
461 pushPS(popPS() <= 0 ? -1 : 0)
465 ZGE = defPrimWord("0>=", () -> begin
466 pushPS(popPS() >= 0 ? -1 : 0)
470 AND = defPrimWord("AND", () -> begin
477 OR = defPrimWord("OR", () -> begin
484 XOR = defPrimWord("XOR", () -> begin
491 INVERT = defPrimWord("INVERT", () -> begin
498 LIT = defPrimWord("LIT", () -> begin
506 STORE = defPrimWord("!", () -> begin
513 FETCH = defPrimWord("@", () -> begin
519 ADDSTORE = defPrimWord("+!", () -> begin
526 SUBSTORE = defPrimWord("-!", () -> begin
536 TOR = defPrimWord(">R", () -> begin
541 FROMR = defPrimWord("R>", () -> begin
546 RFETCH = defPrimWord("R@", () -> begin
551 RSPFETCH = defPrimWord("RSP@", () -> begin
556 RSPSTORE = defPrimWord("RSP!", () -> begin
561 RDROP = defPrimWord("RDROP", () -> begin
568 PSPFETCH = defPrimWord("PSP@", () -> begin
573 PSPSTORE = defPrimWord("PSP!", () -> begin
580 WFETCH = defPrimWord("W@", () -> begin
585 WSTORE = defPrimWord("W!", () -> begin
592 sources = Array{Any,1}()
593 currentSource() = sources[length(sources)]
596 NUMTIB, NUMTIB_CFA = defNewVar("#TIB", 0)
597 TOIN, TOIN_CFA = defNewVar(">IN", 0)
598 EOF = defConst("EOF", 4)
600 KEY = defPrimWord("KEY", () -> begin
601 if mem[TOIN] >= mem[NUMTIB]
604 if !eof(currentSource())
605 line = readline(currentSource())
606 mem[NUMTIB] = length(line)
614 pushPS(mem[TIB + mem[TOIN]])
620 EMIT = defPrimWord("EMIT", () -> begin
625 WORD = defPrimWord("WORD", () -> begin
642 if c == '\n' || c == eof_char
648 if c == ' ' || c == '\t'
658 if c == '\n' || c == eof_char
659 # Treat newline as a special word
661 mem[wordAddr + offset] = Int64(c)
668 mem[wordAddr + offset] = Int64(c)
674 if c == ' ' || c == '\t' || c == '\n' || c == eof_char
689 BASE, BASE_CFA = defNewVar("BASE", 10)
690 NUMBER = defPrimWord("NUMBER", () -> begin
695 s = getString(wordAddr, wordLen)
698 pushPS(parse(Int64, s, mem[BASE]))
701 pushPS(1) # Error indication
707 # Dictionary searches
709 FIND = defPrimWord("FIND", () -> begin
713 word = lowercase(getString(wordAddr, wordLen))
718 while (latest = mem[latest]) > 0
719 lenAndFlags = mem[latest+1]
720 len = lenAndFlags & F_LENMASK
721 hidden = (lenAndFlags & F_HIDDEN) == F_HIDDEN
723 if hidden || len != wordLen
728 thisWord = lowercase(getString(thisAddr, len))
730 if lowercase(thisWord) == lowercase(word)
740 TOCFA = defPrimWord(">CFA", () -> begin
743 lenAndFlags = mem[addr+1]
744 len = lenAndFlags & F_LENMASK
746 pushPS(addr + 2 + len)
751 TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
755 BRANCH = defPrimWord("BRANCH", () -> begin
756 reg.IP += mem[reg.IP]
760 ZBRANCH = defPrimWord("0BRANCH", () -> begin
762 reg.IP += mem[reg.IP]
772 HEADER = defPrimWord("HEADER", () -> begin
776 word = getString(wordAddr, wordLen)
778 createHeader(word, 0)
783 COMMA = defPrimWord(",", () -> begin
784 mem[mem[HERE]] = popPS()
790 STATE, STATE_CFA = defNewVar("STATE", 0)
792 LBRAC = defPrimWord("[", () -> begin
797 RBRAC = defPrimWord("]", () -> begin
802 HIDDEN = defPrimWord("HIDDEN", () -> begin
804 mem[addr] = mem[addr] $ F_HIDDEN
808 HIDE = defWord("HIDE",
818 LATEST_CFA, FETCH, HIDDEN,
822 SEMICOLON = defWord(";",
824 LATEST_CFA, FETCH, HIDDEN,
826 EXIT], flags=F_IMMED)
828 IMMEDIATE = defPrimWord("IMMEDIATE", () -> begin
829 lenAndFlagsAddr = mem[LATEST] + 1
830 mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
835 [WORD, FIND, TOCFA, EXIT])
837 BTICK = defWord("[']",
838 [FROMR, DUP, INCR, TOR, FETCH, EXIT])
843 LITSTRING = defPrimWord("LITSTRING", () -> begin
853 TELL = defPrimWord("TELL", () -> begin
856 str = getString(addr, len)
863 EXECUTE = defPrimWord("EXECUTE", () -> begin
868 type ParseError <: Exception
869 wordName::ASCIIString
871 Base.showerror(io::IO, ex::ParseError) = print(io, "Parse error at word: '$(ex.wordName)'.")
873 DEBUG, DEBUG_CFA = defNewVar("DEBUG", 0)
875 INTERPRET = defPrimWord("INTERPRET", () -> begin
879 wordName = getString(mem[reg.PSP-1], mem[reg.PSP])
881 println("... ", replace(replace(wordName, "\004", "EOF"), "\n", "\\n"), " ...")
884 callPrim(mem[TWODUP])
887 wordAddr = mem[reg.PSP]
892 isImmediate = (mem[wordAddr+1] & F_IMMED) != 0
895 callPrim(mem[NROT]) # get rid of extra copy of word string details
899 if mem[STATE] == 0 || isImmediate
901 return callPrim(mem[EXECUTE])
903 # Append CFA to dictionary
907 # Not in dictionary, assume number
911 callPrim(mem[NUMBER])
914 throw(ParseError(wordName))
918 # Number already on stack!
920 # Append literal to dictionary
930 QUIT = defWord("QUIT",
935 BYE = defPrimWord("BYE", () -> begin
939 PROMPT = defPrimWord("PROMPT", () -> begin
943 NL = defPrimWord("\n", () -> begin
944 if mem[STATE] == 0 && currentSource() == STDIN
945 callPrim(mem[PROMPT])
950 INCLUDE = defPrimWord("INCLUDE", () -> begin
954 word = getString(wordAddr, wordLen)
956 push!(sources, open(word, "r"))
964 EOF_WORD = defPrimWord("\x04", () -> begin
965 if currentSource() != STDIN
966 close(currentSource())
972 if currentSource() == STDIN
973 callPrim(mem[PROMPT])
984 CHAR = defPrimWord("CHAR", () -> begin
988 word = getString(wordAddr, wordLen)
989 pushPS(Int64(word[1]))
995 initFileName = nothing
997 initFileName = "lib.4th"
998 elseif isfile(Pkg.dir("forth/src/lib.4th"))
999 initFileName = Pkg.dir("forth/src/lib.4th")
1004 function run(;initialize=true)
1005 # Begin with STDIN as source
1006 push!(sources, STDIN)
1008 global initialized, initFileName
1009 if !initialized && initialize
1010 if initFileName != nothing
1011 print("Including definitions from $initFileName...")
1012 push!(sources, open(initFileName, "r"))
1015 println("No library file found. Only primitive words available.")
1019 # Start with IP pointing to first instruction of outer interpreter
1022 # Primitive processing loop.
1023 # Everyting else is simply a consequence of this loop!
1028 println("Evaluating prim ", jmp," ", primNames[-jmp])
1034 showerror(STDOUT, ex)
1037 while !isempty(sources) && currentSource() != STDIN
1038 close(pop!(sources))
1053 function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
1054 chars = Array{Char,1}(cellsPerLine)
1056 lineStartAddr = cellsPerLine*div((startAddr-1),cellsPerLine) + 1
1057 endAddr = startAddr + count - 1
1059 q, r = divrem((endAddr-lineStartAddr+1), cellsPerLine)
1060 numLines = q + (r > 0 ? 1 : 0)
1066 for c in 1:cellsPerLine
1067 if i >= startAddr && i <= endAddr
1069 if mem[i]>=32 && mem[i]<128
1070 chars[c] = Char(mem[i])
1082 println("\t", ASCIIString(chars))
1087 count = reg.PSP - mem[PSP0]
1091 for i in (mem[PSP0]+1):reg.PSP
1096 println("Parameter stack empty")
1101 count = reg.RSP - mem[RSP0]
1105 for i in (mem[RSP0]+1):reg.RSP
1110 println("Return stack empty")
1114 DUMP = defPrimWord("DUMP", () -> begin
1118 dump(addr, count=count)