4 size_mem = 1000000 # 1 mega-int
7 size_RS = 1000 # Return stack size
8 size_PS = 1000 # Parameter stack size
9 size_TIB = 1000 # 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)
234 defConst("MEMSIZE", size_mem)
236 F_IMMED = defConst("F_IMMED", 128)
237 F_HIDDEN = defConst("F_HIDDEN", 256)
238 F_LENMASK = defConst("F_LENMASK", 127)
240 # Basic forth primitives
242 DROP = defPrimWord("DROP", () -> begin
247 SWAP = defPrimWord("SWAP", () -> begin
255 DUP = defPrimWord("DUP", () -> begin
261 OVER = defPrimWord("OVER", () -> begin
263 pushPS(mem[reg.PSP-1])
267 ROT = defPrimWord("ROT", () -> begin
277 NROT = defPrimWord("-ROT", () -> begin
288 TWODROP = defPrimWord("2DROP", () -> begin
294 TWODUP = defPrimWord("2DUP", () -> begin
303 TWOSWAP = defPrimWord("2SWAP", () -> begin
315 TWOOVER = defPrimWord("2OVER", () -> begin
324 QDUP = defPrimWord("?DUP", () -> begin
333 INCR = defPrimWord("1+", () -> begin
339 DECR = defPrimWord("1-", () -> begin
345 INCR2 = defPrimWord("2+", () -> begin
351 DECR2 = defPrimWord("2-", () -> begin
357 ADD = defPrimWord("+", () -> begin
364 SUB = defPrimWord("-", () -> begin
371 MUL = defPrimWord("*", () -> begin
378 DIVMOD = defPrimWord("/MOD", () -> begin
387 TWOMUL = defPrimWord("2*", () -> begin
392 TWODIV = defPrimWord("2/", () -> begin
397 EQU = defPrimWord("=", () -> begin
400 pushPS(a==b ? -1 : 0)
404 NEQU = defPrimWord("<>", () -> begin
407 pushPS(a!=b ? -1 : 0)
411 LT = defPrimWord("<", () -> begin
418 GT = defPrimWord(">", () -> begin
425 LE = defPrimWord("<=", () -> begin
428 pushPS(a<=b ? -1 : 0)
432 GE = defPrimWord(">=", () -> begin
435 pushPS(a>=b ? -1 : 0)
439 ZEQU = defPrimWord("0=", () -> begin
440 pushPS(popPS() == 0 ? -1 : 0)
444 ZNEQU = defPrimWord("0<>", () -> begin
445 pushPS(popPS() != 0 ? -1 : 0)
449 ZLT = defPrimWord("0<", () -> begin
450 pushPS(popPS() < 0 ? -1 : 0)
454 ZGT = defPrimWord("0>", () -> begin
455 pushPS(popPS() > 0 ? -1 : 0)
459 ZLE = defPrimWord("0<=", () -> begin
460 pushPS(popPS() <= 0 ? -1 : 0)
464 ZGE = defPrimWord("0>=", () -> begin
465 pushPS(popPS() >= 0 ? -1 : 0)
469 AND = defPrimWord("AND", () -> begin
476 OR = defPrimWord("OR", () -> begin
483 XOR = defPrimWord("XOR", () -> begin
490 INVERT = defPrimWord("INVERT", () -> begin
497 LIT = defPrimWord("LIT", () -> begin
505 STORE = defPrimWord("!", () -> begin
512 FETCH = defPrimWord("@", () -> begin
518 ADDSTORE = defPrimWord("+!", () -> begin
525 SUBSTORE = defPrimWord("-!", () -> begin
535 TOR = defPrimWord(">R", () -> begin
540 FROMR = defPrimWord("R>", () -> begin
545 RFETCH = defPrimWord("R@", () -> begin
550 RSPFETCH = defPrimWord("RSP@", () -> begin
555 RSPSTORE = defPrimWord("RSP!", () -> begin
560 RDROP = defPrimWord("RDROP", () -> begin
567 PSPFETCH = defPrimWord("PSP@", () -> begin
572 PSPSTORE = defPrimWord("PSP!", () -> begin
579 WFETCH = defPrimWord("W@", () -> begin
584 WSTORE = defPrimWord("W!", () -> begin
591 sources = Array{Any,1}()
592 currentSource() = sources[length(sources)]
594 EOF = defConst("EOF", 4)
596 EMIT = defPrimWord("EMIT", () -> begin
601 SPAN, SPAN_CFA = defNewVar("SPAN", 0)
602 EXPECT = defPrimWord("EXPECT", () -> begin
606 if !eof(currentSource())
607 line = readline(currentSource())
608 mem[SPAN] = max(length(line), maxLen)
609 putString(line[1:mem[SPAN]], addr)
618 BASE, BASE_CFA = defNewVar("BASE", 10)
619 NUMBER = defPrimWord("NUMBER", () -> begin
622 wordLen = mem[wordAddr-1]
624 s = getString(wordAddr, wordLen)
626 pushPS(parse(Int64, s, mem[BASE]))
631 # Dictionary searches
633 FIND = defPrimWord("FIND", () -> begin
635 countedAddr = popPS()
636 wordAddr = countedAddr + 1
637 wordLen = mem[countedAddr]
638 word = lowercase(getString(wordAddr, wordLen))
643 while (latest = mem[latest]) > 0
644 lenAndFlags = mem[latest+1]
645 len = lenAndFlags & F_LENMASK
646 hidden = (lenAndFlags & F_HIDDEN) == F_HIDDEN
648 if hidden || len != wordLen
653 thisWord = lowercase(getString(thisAddr, len))
655 if lowercase(thisWord) == lowercase(word)
665 TOCFA = defPrimWord(">CFA", () -> begin
668 lenAndFlags = mem[addr+1]
669 len = lenAndFlags & F_LENMASK
671 pushPS(addr + 2 + len)
676 TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
680 BRANCH = defPrimWord("BRANCH", () -> begin
681 reg.IP += mem[reg.IP]
685 ZBRANCH = defPrimWord("0BRANCH", () -> begin
687 reg.IP += mem[reg.IP]
697 LITSTRING = defPrimWord("LITSTRING", () -> begin
707 TYPE = defPrimWord("TYPE", () -> begin
710 str = getString(addr, len)
718 NUMTIB, NUMTIB_CFA = defNewVar("#TIB", 0)
719 TOIN, TOIN_CFA = defNewVar(">IN", 0)
721 QUERY = defWord("QUERY",
722 [LIT, TIB, LIT, 80, EXPECT,
723 LIT, SPAN, FETCH, NUMTIB, STORE,
727 EXECUTE = defPrimWord("EXECUTE", () -> begin
732 STATE, STATE_CFA = defNewVar("STATE", 0)
734 INTERPRET = defWord("INTERPRET",
735 [LIT, 32, WORD, # Read next space-delimited word
737 DUP, FETCH, ZEQ, ZBRANCH, 3,
738 DROP, EXIT, # Exit if TIB is exhausted
740 STATE_CFA, FETCH, ZBRANCH, 26,
742 DUP, FIND, ZBRANCH, 17,
745 DUP, TOCFA, SWAP, INCR, FETCH, LIT, F_IMMED, AND, ZBRANCH, 4,
746 # Immediate: Execute!
747 EXECUTE, BRANCH, -30,
749 # Not immediate: Compile!
752 # No word found, parse number
753 NUMBER, BTICK, LIT, COMMA, BRANCH, -39,
756 DUP, FIND, ZBRANCH, 5,
758 # Found word. Execute!
759 TOCFA, EXECUTE, BRANCH, -47,
761 # No word found, parse number and leave on stack
766 PROMPT = defPrimWord("PROMPT", () -> begin
767 if (mem[STATE] == 0 and currentSource() == STDIN)
772 QUIT = defWord("QUIT",
778 BYE = defPrimWord("BYE", () -> begin
782 INCLUDE = defPrimWord("INCLUDE", () -> begin
786 word = getString(wordAddr, wordLen)
788 push!(sources, open(word, "r"))
798 HEADER = defPrimWord("HEADER", () -> begin
801 wordLen = mem[wordAddr-1]
802 word = getString(wordAddr, wordLen)
804 createHeader(word, 0)
809 COMMA = defPrimWord(",", () -> begin
810 mem[mem[HERE]] = popPS()
816 LBRAC = defPrimWord("[", () -> begin
821 RBRAC = defPrimWord("]", () -> begin
826 HIDDEN = defPrimWord("HIDDEN", () -> begin
828 mem[addr] = mem[addr] $ F_HIDDEN
832 HIDE = defWord("HIDE",
842 LATEST_CFA, FETCH, HIDDEN,
846 SEMICOLON = defWord(";",
848 LATEST_CFA, FETCH, HIDDEN,
850 EXIT], flags=F_IMMED)
852 IMMEDIATE = defPrimWord("IMMEDIATE", () -> begin
853 lenAndFlagsAddr = mem[LATEST] + 1
854 mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
859 [WORD, FIND, TOCFA, EXIT])
861 BTICK = defWord("[']",
862 [FROMR, DUP, INCR, TOR, FETCH, EXIT])
866 CREATE = defWord("CREATE",
869 LIT, DOVAR, COMMA, EXIT]);
871 DODOES = defPrim(() -> begin
877 defConst("DODOES", DODOES)
879 FROMDOES_PAREN = defWord("(DOES>)",
880 [DODOES, LATEST, FETCH, TOCFA, STORE, EXIT])
882 FROMDOES = defWord("DOES>",
883 [BTICK, FROMDOES_PAREN, COMMA, BTICK, EXIT, COMMA,
884 BTICK, LIT, COMMA, LATEST, FETCH, TODFA, COMMA], flags=F_IMMED)
891 initFileName = nothing
893 initFileName = "lib.4th"
894 elseif isfile(Pkg.dir("forth/src/lib.4th"))
895 initFileName = Pkg.dir("forth/src/lib.4th")
898 function run(;initialize=false)
899 # Begin with STDIN as source
900 push!(sources, STDIN)
902 global initialized, initFileName
903 if !initialized && initialize
904 if initFileName != nothing
905 print("Including definitions from $initFileName...")
906 push!(sources, open(initFileName, "r"))
909 println("No library file found. Only primitive words available.")
913 # Start with IP pointing to first instruction of outer interpreter
916 # Primitive processing loop.
917 # Everyting else is simply a consequence of this loop!
922 println("Evaluating prim ", jmp," ", primNames[-jmp])
928 showerror(STDOUT, ex)
931 while !isempty(sources) && currentSource() != STDIN
947 function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
948 chars = Array{Char,1}(cellsPerLine)
950 lineStartAddr = cellsPerLine*div((startAddr-1),cellsPerLine) + 1
951 endAddr = startAddr + count - 1
953 q, r = divrem((endAddr-lineStartAddr+1), cellsPerLine)
954 numLines = q + (r > 0 ? 1 : 0)
960 for c in 1:cellsPerLine
961 if i >= startAddr && i <= endAddr
963 if mem[i]>=32 && mem[i]<128
964 chars[c] = Char(mem[i])
976 println("\t", ASCIIString(chars))
981 count = reg.PSP - mem[PSP0]
985 for i in (mem[PSP0]+1):reg.PSP
990 println("Parameter stack empty")
995 count = reg.RSP - mem[RSP0]
999 for i in (mem[RSP0]+1):reg.RSP
1004 println("Return stack empty")
1008 DUMP = defPrimWord("DUMP", () -> begin
1012 dump(addr, count=count)