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 function callPrim(addr::Int64)
125 if addr >=0 || -addr>length(primitives)
126 error("Attempted to execute non-existent primitive at address $addr.")
131 getPrimName(addr::Int64) = primNames[-addr]
133 # Word creation functions
139 function createHeader(name::AbstractString, flags::Int64)
140 mem[mem[HERE]] = mem[LATEST]
141 mem[LATEST] = mem[HERE]
144 mem[mem[HERE]] = length(name) | flags; mem[HERE] += 1
145 putString(name, mem[HERE]); mem[HERE] += length(name)
148 function defPrimWord(name::AbstractString, f::Function; flags::Int64=0)
149 createHeader(name, flags)
151 codeWordAddr = mem[HERE]
152 mem[codeWordAddr] = defPrim(f, name=name)
158 function defWord(name::AbstractString, wordAddrs::Array{Int64,1}; flags::Int64=0)
159 createHeader(name, flags)
162 mem[mem[HERE]] = DOCOL
165 for wordAddr in wordAddrs
166 mem[mem[HERE]] = wordAddr
173 # Variable creation functions
175 function defExistingVar(name::AbstractString, varAddr::Int64; flags::Int64=0)
177 defPrimWord(name, eval(:(() -> begin
183 function defNewVar(name::AbstractString, initial::Int64; flags::Int64=0)
184 createHeader(name, flags)
186 codeWordAddr = mem[HERE]
187 varAddr = mem[HERE] + 1
189 mem[mem[HERE]] = DOVAR; mem[HERE] += 1
190 mem[mem[HERE]] = initial; mem[HERE] += 1
192 return varAddr, codeWordAddr
195 function defConst(name::AbstractString, val::Int64; flags::Int64=0)
196 createHeader(name, flags)
198 codeWordAddr = mem[HERE]
200 mem[mem[HERE]] = DOCON; mem[HERE] += 1
201 mem[mem[HERE]] = val; mem[HERE] += 1
206 # Threading Primitives (inner interpreter)
208 NEXT = defPrim(() -> begin
214 DOCOL = defPrim(() -> begin
220 DOVAR = defPrim(() -> begin
225 DOCON = defPrim(() -> begin
226 pushPS(mem[reg.W + 1])
230 EXIT = defPrimWord("EXIT", () -> begin
235 # Dictionary entries for core built-in variables, constants
237 HERE_CFA = defExistingVar("HERE", HERE)
238 LATEST_CFA = defExistingVar("LATEST", LATEST)
239 PSP0_CFA = defExistingVar("PSP0", PSP0)
240 RSP0_CFA = defExistingVar("RSP0", RSP0)
242 defConst("DOCOL", DOCOL)
243 defConst("DOCON", DOCON)
244 defConst("DOVAR", DOVAR)
246 defConst("DICT", DICT)
247 defConst("MEMSIZE", size_mem)
249 F_IMMED_CFA = defConst("F_IMMED", F_IMMED)
250 F_HIDDEN_CFA = defConst("F_HIDDEN", F_HIDDEN)
251 F_LENMASK_CFA = defConst("F_LENMASK", F_LENMASK)
253 # Basic forth primitives
255 DROP = defPrimWord("DROP", () -> begin
260 SWAP = defPrimWord("SWAP", () -> begin
268 DUP = defPrimWord("DUP", () -> begin
274 OVER = defPrimWord("OVER", () -> begin
276 pushPS(mem[reg.PSP-1])
280 ROT = defPrimWord("ROT", () -> begin
290 NROT = defPrimWord("-ROT", () -> begin
301 TWODROP = defPrimWord("2DROP", () -> begin
307 TWODUP = defPrimWord("2DUP", () -> begin
316 TWOSWAP = defPrimWord("2SWAP", () -> begin
328 TWOOVER = defPrimWord("2OVER", () -> begin
337 QDUP = defPrimWord("?DUP", () -> begin
346 INCR = defPrimWord("1+", () -> begin
352 DECR = defPrimWord("1-", () -> begin
358 INCR2 = defPrimWord("2+", () -> begin
364 DECR2 = defPrimWord("2-", () -> begin
370 ADD = defPrimWord("+", () -> begin
377 SUB = defPrimWord("-", () -> begin
384 MUL = defPrimWord("*", () -> begin
391 DIVMOD = defPrimWord("/MOD", () -> begin
400 TWOMUL = defPrimWord("2*", () -> begin
405 TWODIV = defPrimWord("2/", () -> begin
410 EQ = defPrimWord("=", () -> begin
413 pushPS(a==b ? -1 : 0)
417 NE = defPrimWord("<>", () -> begin
420 pushPS(a!=b ? -1 : 0)
424 LT = defPrimWord("<", () -> begin
431 GT = defPrimWord(">", () -> begin
438 LE = defPrimWord("<=", () -> begin
441 pushPS(a<=b ? -1 : 0)
445 GE = defPrimWord(">=", () -> begin
448 pushPS(a>=b ? -1 : 0)
452 ZE = defPrimWord("0=", () -> begin
453 pushPS(popPS() == 0 ? -1 : 0)
457 ZNE = defPrimWord("0<>", () -> begin
458 pushPS(popPS() != 0 ? -1 : 0)
462 ZLT = defPrimWord("0<", () -> begin
463 pushPS(popPS() < 0 ? -1 : 0)
467 ZGT = defPrimWord("0>", () -> begin
468 pushPS(popPS() > 0 ? -1 : 0)
472 ZLE = defPrimWord("0<=", () -> begin
473 pushPS(popPS() <= 0 ? -1 : 0)
477 ZGE = defPrimWord("0>=", () -> begin
478 pushPS(popPS() >= 0 ? -1 : 0)
482 AND = defPrimWord("AND", () -> begin
489 OR = defPrimWord("OR", () -> begin
496 XOR = defPrimWord("XOR", () -> begin
503 INVERT = defPrimWord("INVERT", () -> begin
510 LIT = defPrimWord("LIT", () -> begin
518 STORE = defPrimWord("!", () -> begin
525 FETCH = defPrimWord("@", () -> begin
531 ADDSTORE = defPrimWord("+!", () -> begin
538 SUBSTORE = defPrimWord("-!", () -> begin
548 TOR = defPrimWord(">R", () -> begin
553 FROMR = defPrimWord("R>", () -> begin
558 RFETCH = defPrimWord("R@", () -> begin
563 RSPFETCH = defPrimWord("RSP@", () -> begin
568 RSPSTORE = defPrimWord("RSP!", () -> begin
573 RDROP = defPrimWord("RDROP", () -> begin
580 PSPFETCH = defPrimWord("PSP@", () -> begin
585 PSPSTORE = defPrimWord("PSP!", () -> begin
592 WFETCH = defPrimWord("W@", () -> begin
597 WSTORE = defPrimWord("W!", () -> begin
604 sources = Array{Any,1}()
605 currentSource() = sources[length(sources)]
607 EOF_CFA = defConst("EOF", 4)
609 EMIT = defPrimWord("EMIT", () -> begin
614 SPAN, SPAN_CFA = defNewVar("SPAN", 0)
615 EXPECT = defPrimWord("EXPECT", () -> begin
619 if !eof(currentSource())
620 line = chomp(readline(currentSource()))
621 mem[SPAN] = min(length(line), maxLen)
622 putString(line[1:mem[SPAN]], addr)
631 BASE, BASE_CFA = defNewVar("BASE", 10)
632 NUMBER = defPrimWord("NUMBER", () -> begin
634 wordLen = mem[wordAddr-1]
636 s = getString(wordAddr, wordLen)
638 pushPS(parse(Int64, s, mem[BASE]))
643 # Dictionary searches
645 FIND = defPrimWord("FIND", () -> begin
647 countedAddr = popPS()
648 wordAddr = countedAddr + 1
649 wordLen = mem[countedAddr]
650 word = lowercase(getString(wordAddr, wordLen))
655 while (latest = mem[latest]) > 0
656 lenAndFlags = mem[latest+1]
657 len = lenAndFlags & F_LENMASK
658 hidden = (lenAndFlags & F_HIDDEN) == F_HIDDEN
660 if hidden || len != wordLen
665 thisWord = lowercase(getString(thisAddr, len))
667 if lowercase(thisWord) == lowercase(word)
677 TOCFA = defPrimWord(">CFA", () -> begin
680 lenAndFlags = mem[addr+1]
681 len = lenAndFlags & F_LENMASK
683 pushPS(addr + 2 + len)
688 TOPFA = defWord(">PFA", [TOCFA, INCR, EXIT])
692 BRANCH = defPrimWord("BRANCH", () -> begin
693 reg.IP += mem[reg.IP]
697 ZBRANCH = defPrimWord("0BRANCH", () -> begin
699 reg.IP += mem[reg.IP]
709 LITSTRING = defPrimWord("LITSTRING", () -> begin
719 TYPE = defPrimWord("TYPE", () -> begin
722 str = getString(addr, len)
729 TRACE = defPrimWord("TRACE", () -> begin
730 println("reg.W: $(reg.W) reg.IP: $(reg.IP)")
731 print("PS: "); printPS()
732 print("RS: "); printRS()
739 COMMA = defPrimWord(",", () -> begin
740 mem[mem[HERE]] = popPS()
746 BTICK = defWord("[']",
747 [FROMR, DUP, INCR, TOR, FETCH, EXIT])
749 EXECUTE = defPrimWord("EXECUTE", () -> begin
754 TIB_CFA = defConst("TIB", TIB)
755 NUMTIB, NUMTIB_CFA = defNewVar("#TIB", 0)
756 TOIN, TOIN_CFA = defNewVar(">IN", 0)
758 QUERY = defWord("QUERY",
759 [TIB_CFA, LIT, 80, EXPECT,
760 SPAN_CFA, FETCH, NUMTIB_CFA, STORE,
761 LIT, 0, TOIN_CFA, STORE,
764 WORD = defPrimWord("WORD", () -> begin
767 # Chew up initial occurrences of delim
768 while (mem[TOIN]<mem[NUMTIB] && mem[TIB+mem[TOIN]] == delim)
772 countAddr = mem[HERE]
775 # Start reading in word
777 while (mem[TOIN]<mem[NUMTIB])
778 mem[addr] = mem[TIB+mem[TOIN]]
781 if (mem[addr] == delim)
790 mem[countAddr] = count
796 PARSE = defPrimWord("PARSE", () -> begin
799 # Chew up initial occurrences of delim
802 # Start reading input stream
804 while (mem[TOIN]<mem[NUMTIB])
805 mem[addr] = mem[TIB+mem[TOIN]]
808 if (mem[addr] == delim)
822 BYE = defPrimWord("BYE", () -> begin
827 STATE, STATE_CFA = defNewVar("STATE", 0)
829 INTERPRET = defWord("INTERPRET",
830 [LIT, 32, WORD, # Read next space-delimited word
832 DUP, FETCH, ZE, ZBRANCH, 3,
833 DROP, EXIT, # Exit if TIB is exhausted
835 STATE_CFA, FETCH, ZBRANCH, 31,
837 DUP, FIND, QDUP, ZBRANCH, 19,
841 DUP, TOCFA, SWAP, INCR, FETCH, LIT, F_IMMED, AND, ZBRANCH, 4,
842 # Immediate: Execute!
843 EXECUTE, BRANCH, -33,
845 # Not immediate: Compile!
848 # No word found, parse number
849 NUMBER, BTICK, LIT, COMMA, COMMA, BRANCH, -43,
852 DUP, FIND, QDUP, ZBRANCH, 7,
854 # Found word. Execute!
855 SWAP, DROP, TOCFA, EXECUTE, BRANCH, -54,
857 # No word found, parse number and leave on stack
862 PROMPT = defPrimWord("PROMPT", () -> begin
863 if (mem[STATE] == 0 && currentSource() == STDIN)
870 QUIT = defWord("QUIT",
876 INCLUDE = defPrimWord("INCLUDE", () -> begin
880 wordLen = mem[wordAddr-1]
881 word = getString(wordAddr, wordLen)
883 push!(sources, open(word, "r"))
893 HEADER = defPrimWord("HEADER", () -> begin
895 wordLen = mem[wordAddr-1]
896 word = getString(wordAddr, wordLen)
898 createHeader(word, 0)
903 LBRAC = defPrimWord("[", () -> begin
908 RBRAC = defPrimWord("]", () -> begin
913 HIDDEN = defPrimWord("HIDDEN", () -> begin
915 mem[addr] = mem[addr] $ F_HIDDEN
919 HIDE = defWord("HIDE",
929 LATEST_CFA, FETCH, HIDDEN,
933 SEMICOLON = defWord(";",
935 LATEST_CFA, FETCH, HIDDEN,
937 EXIT], flags=F_IMMED)
939 IMMEDIATE = defPrimWord("IMMEDIATE", () -> begin
940 lenAndFlagsAddr = mem[LATEST] + 1
941 mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
949 initFileName = nothing
951 initFileName = "lib.4th"
952 elseif isfile(Pkg.dir("forth/src/lib.4th"))
953 initFileName = Pkg.dir("forth/src/lib.4th")
956 function run(;initialize=true)
957 # Begin with STDIN as source
958 push!(sources, STDIN)
960 global initialized, initFileName
961 if !initialized && initialize
962 if initFileName != nothing
963 print("Including definitions from $initFileName...")
964 push!(sources, open(initFileName, "r"))
967 println("No library file found. Only primitive words available.")
971 # Start with IP pointing to first instruction of outer interpreter
974 # Primitive processing loop.
975 # Everyting else is simply a consequence of this loop!
979 #println("Entering prim $(getPrimName(jmp))")
983 showerror(STDOUT, ex)
986 while !isempty(sources) && currentSource() != STDIN
990 # Want backtrace in here eventually
991 println("reg.W: $(reg.W) reg.IP: $(reg.IP)")
992 print("PS: "); printPS()
993 print("RS: "); printRS()
1007 function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
1008 chars = Array{Char,1}(cellsPerLine)
1010 lineStartAddr = cellsPerLine*div((startAddr-1),cellsPerLine) + 1
1011 endAddr = startAddr + count - 1
1013 q, r = divrem((endAddr-lineStartAddr+1), cellsPerLine)
1014 numLines = q + (r > 0 ? 1 : 0)
1020 for c in 1:cellsPerLine
1021 if i >= startAddr && i <= endAddr
1023 if mem[i]>=32 && mem[i]<128
1024 chars[c] = Char(mem[i])
1036 println("\t", ASCIIString(chars))
1041 count = reg.PSP - mem[PSP0]
1045 for i in (mem[PSP0]+1):reg.PSP
1050 println("Parameter stack empty")
1055 count = reg.RSP - mem[RSP0]
1059 for i in (mem[RSP0]+1):reg.RSP
1064 println("Return stack empty")
1068 DUMP = defPrimWord("DUMP", () -> begin
1072 dump(addr, count=count)