X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=src%2Fforth.jl;h=fb7121c27d13851b98c445e2daf7db1000219e4c;hb=87b17b0ee12c90f028186761fbb2bd5f6b4008eb;hp=7f5756efaf767e3ed7fda33c0fd4dc003aac941a;hpb=c917b31a088bbbfa0d279626f8092aaa7a991ec7;p=forth.jl.git

diff --git a/src/forth.jl b/src/forth.jl
index 7f5756e..fb7121c 100644
--- a/src/forth.jl
+++ b/src/forth.jl
@@ -1,93 +1,1081 @@
 module forth
 
-instream = STDIN
+# VM mem size
+size_mem = 1000000 # 1 mega-int
 
-currentLine = ""
-currentPos = 0
+# Buffer sizes
+size_RS = 1000   # Return stack size
+size_PS = 1000   # Parameter stack size
+size_TIB = 1000  # Terminal input buffer size
 
-function readPattern(pattern::Regex)
+# The mem array constitutes the memory of the VM. It has the following geography:
+#
+# mem = +-----------------------+
+#       | Built-in Variables    |
+#       +-----------------------+
+#       | Return Stack          |
+#       +-----------------------+
+#       | Parameter Stack       |
+#       +-----------------------+
+#       | Terminal Input Buffer |
+#       +-----------------------+
+#       | Dictionary            |
+#       +-----------------------+
+#
+# Note that all words (user-defined, primitive, variables, etc) are included in
+# the dictionary.
+#
+# Simple linear addressing is used with one exception: references to primitive code
+# blocks, which are represented as anonymous functions, appear as negative indicies
+# into the primitives array which contains these functions.
 
-    if currentPos<1 || currentPos>length(currentLine)
-        if eof(instream)
-            return ""
-        else
-            global currentLine = readline(instream)
-            global currentPos = 1
-        end
+mem = Array{Int64,1}(size_mem)
+primitives = Array{Function,1}()
+primNames = Array{ASCIIString,1}()
+
+# Built-in variables
+
+nextVarAddr = 1
+HERE = nextVarAddr; nextVarAddr += 1
+LATEST = nextVarAddr; nextVarAddr += 1
+
+RSP0 = nextVarAddr                  # bottom of RS
+PSP0 = RSP0 + size_RS               # bottom of PS
+TIB = PSP0 + size_PS                # address of terminal input buffer
+mem[HERE] = TIB + size_TIB          # location of bottom of dictionary
+mem[LATEST] = 0                     # no previous definition
+
+DICT = mem[HERE] # Save bottom of dictionary as constant
+
+# VM registers
+type Reg
+    RSP::Int64  # Return stack pointer
+    PSP::Int64  # Parameter/data stack pointer
+    IP::Int64   # Instruction pointer
+    W::Int64    # Working register
+end
+reg = Reg(RSP0, PSP0, 0, 0)
+
+# Stack manipulation functions
+
+type ParamStackUnderflow <: Exception end
+type ReturnStackUnderflow <: Exception end
+
+Base.showerror(io::IO, ex::ParamStackUnderflow) = print(io, "Parameter stack underflow.")
+Base.showerror(io::IO, ex::ReturnStackUnderflow) = print(io, "Return stack underflow.")
+
+getRSDepth() = reg.RSP - RSP0
+getPSDepth() = reg.PSP - PSP0
+
+function ensurePSDepth(depth::Int64)
+    if getPSDepth()<depth
+        throw(ParamStackUnderflow())
     end
+end
+
+function ensureRSDepth(depth::Int64)
+    if getRSDepth()<depth
+        throw(ReturnStackUnderflow())
+    end
+end
+
+function pushRS(val::Int64)
+    mem[reg.RSP+=1] = val
+end
+
+function popRS()
+    ensureRSDepth(1)
+
+    val = mem[reg.RSP]
+    reg.RSP -= 1
+    return val
+end
+
+function pushPS(val::Int64)
+    mem[reg.PSP += 1] = val
+end
+
+function popPS()
+    ensurePSDepth(1)
+
+    val = mem[reg.PSP]
+    reg.PSP -= 1
+    return val
+end
+
+# Handy functions for adding/retrieving strings to/from memory.
+
+getString(addr::Int64, len::Int64) = ASCIIString([Char(c) for c in mem[addr:(addr+len-1)]])
+
+function putString(str::ASCIIString, addr::Int64)
+    mem[addr:(addr+length(str)-1)] = [Int64(c) for c in str]
+end
+
+# Primitive creation and calling functions
+
+function defPrim(f::Function; name="nameless")
+    push!(primitives, f)
+    push!(primNames, replace(name, "\004", "EOF"))
 
-    m = match(pattern, currentLine[currentPos:length(currentLine)])
-    if m != nothing
-        global currentPos += length(m.match)
-        return m.match
+    return -length(primitives)
+end
+
+function callPrim(addr::Int64)
+    if addr >=0 || -addr>length(primitives)
+        error("Attempted to execute non-existent primitive at address $addr.")
     else
-        return ""
+        primitives[-addr]()
     end
 end
+getPrimName(addr::Int64) = primNames[-addr]
+
+# Word creation functions
+
+F_IMMED = 128
+F_HIDDEN = 256
+F_LENMASK = 127
+
+function createHeader(name::AbstractString, flags::Int64)
+    mem[mem[HERE]] = mem[LATEST]
+    mem[LATEST] = mem[HERE]
+    mem[HERE] += 1
+
+    mem[mem[HERE]] = length(name) | flags; mem[HERE] += 1
+    putString(name, mem[HERE]); mem[HERE] += length(name)
+end
+
+function defPrimWord(name::AbstractString, f::Function; flags::Int64=0)
+    createHeader(name, flags)
+
+    codeWordAddr = mem[HERE]
+    mem[codeWordAddr] = defPrim(f, name=name)
+    mem[HERE] += 1
+
+    return codeWordAddr
+end
+
+function defWord(name::AbstractString, wordAddrs::Array{Int64,1}; flags::Int64=0)
+    createHeader(name, flags)
 
-readSpaces() = readPattern(r"^([ \t]*)")
-readWord() = readPattern(r"^([^\s]+)")
-readNewline() = readPattern(r"^(\n)")
-readRestOfLine() = readPattern(r"^([^\n]*)")
+    addr = mem[HERE]
+    mem[mem[HERE]] = DOCOL
+    mem[HERE] += 1
 
-word = ""
-function getWordOrNewline()
-    global word = readWord()
-    if word == ""
-        global word = readNewline()
+    for wordAddr in wordAddrs
+        mem[mem[HERE]] = wordAddr
+        mem[HERE] += 1
     end
+
+    return addr
+end
+
+# Variable creation functions
+
+function defExistingVar(name::AbstractString, varAddr::Int64; flags::Int64=0)
+
+    defPrimWord(name, eval(:(() -> begin
+        pushPS($(varAddr))
+        return NEXT
+    end)))
+end
+
+function defNewVar(name::AbstractString, initial::Int64; flags::Int64=0)
+    createHeader(name, flags)
+    
+    codeWordAddr = mem[HERE]
+    varAddr = mem[HERE] + 1
+
+    mem[mem[HERE]] = DOVAR; mem[HERE] += 1
+    mem[mem[HERE]] = initial; mem[HERE] += 1
+
+    return varAddr, codeWordAddr
 end
 
-modes = Dict{AbstractString,Function}()
-mode = ""
+function defConst(name::AbstractString, val::Int64; flags::Int64=0)
+    createHeader(name, flags)
+
+    codeWordAddr = mem[HERE]
 
-dict = Dict{AbstractString, Function}()
-dict["%J"] = () -> begin
-    rol = readRestOfLine()
-    println("Evaluating '$rol'")
-    eval(parse(rol))
+    mem[mem[HERE]] = DOCON; mem[HERE] += 1
+    mem[mem[HERE]] = val; mem[HERE] += 1
+
+    return codeWordAddr
 end
 
-function interpretPrimitive()
-    if haskey(dict, word)
-        dict[word]()
-        return true
+# Threading Primitives (inner interpreter)
+
+NEXT = defPrim(() -> begin
+    reg.W = mem[reg.IP]
+    reg.IP += 1
+    return mem[reg.W]
+end, name="NEXT")
+
+DOCOL = defPrim(() -> begin
+    pushRS(reg.IP)
+    reg.IP = reg.W + 1
+    return NEXT
+end, name="DOCOL")
+
+DOVAR = defPrim(() -> begin
+    pushPS(reg.W + 1)
+    return NEXT
+end, name="DOVAR")
+
+DOCON = defPrim(() -> begin
+    pushPS(mem[reg.W + 1])
+    return NEXT
+end, name="DOVAR")
+
+EXIT = defPrimWord("EXIT", () -> begin
+    reg.IP = popRS()
+    return NEXT
+end)
+
+# Dictionary entries for core built-in variables, constants
+
+HERE_CFA = defExistingVar("HERE", HERE)
+LATEST_CFA = defExistingVar("LATEST", LATEST)
+
+PSP0_CFA = defConst("PSP0", PSP0)
+RSP0_CFA = defConst("RSP0", RSP0)
+
+defConst("DOCOL", DOCOL)
+defConst("DOCON", DOCON)
+defConst("DOVAR", DOVAR)
+
+defConst("DICT", DICT)
+defConst("MEMSIZE", size_mem)
+
+F_IMMED_CFA = defConst("F_IMMED", F_IMMED)
+F_HIDDEN_CFA = defConst("F_HIDDEN", F_HIDDEN)
+F_LENMASK_CFA = defConst("F_LENMASK", F_LENMASK)
+
+# Basic forth primitives
+
+DROP = defPrimWord("DROP", () -> begin
+    popPS()
+    return NEXT
+end)
+
+SWAP = defPrimWord("SWAP", () -> begin
+    a = popPS()
+    b = popPS()
+    pushPS(a)
+    pushPS(b)
+    return NEXT
+end)
+
+DUP = defPrimWord("DUP", () -> begin
+    ensurePSDepth(1)
+    pushPS(mem[reg.PSP])
+    return NEXT
+end)
+
+OVER = defPrimWord("OVER", () -> begin
+    ensurePSDepth(2)
+    pushPS(mem[reg.PSP-1])
+    return NEXT
+end)
+
+ROT = defPrimWord("ROT", () -> begin
+    a = popPS()
+    b = popPS()
+    c = popPS()
+    pushPS(b)
+    pushPS(a)
+    pushPS(c)
+    return NEXT
+end)
+
+NROT = defPrimWord("-ROT", () -> begin
+    a = popPS()
+    b = popPS()
+    c = popPS()
+    pushPS(a)
+    pushPS(c)
+    pushPS(b)
+    return NEXT
+end)
+
+
+TWODROP = defPrimWord("2DROP", () -> begin
+    popPS()
+    popPS()
+    return NEXT
+end)
+
+TWODUP = defPrimWord("2DUP", () -> begin
+    ensurePSDepth(2)
+    a = mem[reg.PSP-1]
+    b = mem[reg.PSP]
+    pushPS(a)
+    pushPS(b)
+    return NEXT
+end)
+
+TWOSWAP = defPrimWord("2SWAP", () -> begin
+    a = popPS()
+    b = popPS()
+    c = popPS()
+    d = popPS()
+    pushPS(b)
+    pushPS(a)
+    pushPS(d)
+    pushPS(c)
+    return NEXT
+end)
+
+TWOOVER = defPrimWord("2OVER", () -> begin
+    ensurePSDepth(4)
+    a = mem[reg.PSP-3]
+    b = mem[reg.PSP-2]
+    pushPS(a)
+    pushPS(b)
+    return NEXT
+end)
+
+QDUP = defPrimWord("?DUP", () -> begin
+    ensurePSDepth(1)
+    val = mem[reg.PSP]
+    if val != 0
+        pushPS(val)
+    end
+    return NEXT
+end)
+
+INCR = defPrimWord("1+", () -> begin
+    ensurePSDepth(1)
+    mem[reg.PSP] += 1
+    return NEXT
+end)
+
+DECR = defPrimWord("1-", () -> begin
+    ensurePSDepth(1)
+    mem[reg.PSP] -= 1
+    return NEXT
+end)
+
+INCR2 = defPrimWord("2+", () -> begin
+    ensurePSDepth(1)
+    mem[reg.PSP] += 2
+    return NEXT
+end)
+
+DECR2 = defPrimWord("2-", () -> begin
+    ensurePSDepth(1)
+    mem[reg.PSP] -= 2
+    return NEXT
+end)
+
+ADD = defPrimWord("+", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a+b)
+    return NEXT
+end)
+
+SUB = defPrimWord("-", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a-b)
+    return NEXT
+end)
+
+MUL = defPrimWord("*", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a*b)
+    return NEXT
+end)
+
+DIVMOD = defPrimWord("/MOD", () -> begin
+    b = popPS()
+    a = popPS()
+    q,r = divrem(a,b)
+    pushPS(r)
+    pushPS(q)
+    return NEXT
+end)
+
+TWOMUL = defPrimWord("2*", () -> begin
+    pushPS(popPS() << 1)
+    return NEXT
+end)
+
+TWODIV = defPrimWord("2/", () -> begin
+    pushPS(popPS() >> 1)
+    return NEXT
+end)
+
+EQ = defPrimWord("=", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a==b ? -1 : 0)
+    return NEXT
+end)
+
+NE = defPrimWord("<>", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a!=b ? -1 : 0)
+    return NEXT
+end)
+
+LT = defPrimWord("<", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a<b ? -1 : 0)
+    return NEXT
+end)
+
+GT = defPrimWord(">", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a>b ? -1 : 0)
+    return NEXT
+end)
+
+LE = defPrimWord("<=", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a<=b ? -1 : 0)
+    return NEXT
+end)
+
+GE = defPrimWord(">=", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a>=b ? -1 : 0)
+    return NEXT
+end)
+
+ZE = defPrimWord("0=", () -> begin
+    pushPS(popPS() == 0 ? -1 : 0)
+    return NEXT
+end)
+
+ZNE = defPrimWord("0<>", () -> begin
+    pushPS(popPS() != 0 ? -1 : 0)
+    return NEXT
+end)
+
+ZLT = defPrimWord("0<", () -> begin
+    pushPS(popPS() < 0 ? -1 : 0)
+    return NEXT
+end)
+
+ZGT = defPrimWord("0>", () -> begin
+    pushPS(popPS() > 0 ? -1 : 0)
+    return NEXT
+end)
+
+ZLE = defPrimWord("0<=", () -> begin
+    pushPS(popPS() <= 0 ? -1 : 0)
+    return NEXT
+end)
+
+ZGE = defPrimWord("0>=", () -> begin
+    pushPS(popPS() >= 0 ? -1 : 0)
+    return NEXT
+end)
+
+AND = defPrimWord("AND", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a & b)
+    return NEXT
+end)
+
+OR = defPrimWord("OR", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a | b)
+    return NEXT
+end)
+
+XOR = defPrimWord("XOR", () -> begin
+    b = popPS()
+    a = popPS()
+    pushPS(a $ b)
+    return NEXT
+end)
+
+INVERT = defPrimWord("INVERT", () -> begin
+    pushPS(~popPS())
+    return NEXT
+end)
+
+# Literals
+
+LIT = defPrimWord("LIT", () -> begin
+    pushPS(mem[reg.IP])
+    reg.IP += 1
+    return NEXT
+end)
+
+# Memory primitives
+
+STORE = defPrimWord("!", () -> begin
+    addr = popPS()
+    dat = popPS()
+    mem[addr] = dat
+    return NEXT
+end)
+
+FETCH = defPrimWord("@", () -> begin
+    addr = popPS()
+    pushPS(mem[addr])
+    return NEXT
+end)
+
+ADDSTORE = defPrimWord("+!", () -> begin
+    addr = popPS()
+    toAdd = popPS()
+    mem[addr] += toAdd
+    return NEXT
+end)
+
+SUBSTORE = defPrimWord("-!", () -> begin
+    addr = popPS()
+    toSub = popPS()
+    mem[addr] -= toSub
+    return NEXT
+end)
+
+
+# Return Stack
+
+TOR = defPrimWord(">R", () -> begin
+    pushRS(popPS())
+    return NEXT
+end)
+
+FROMR = defPrimWord("R>", () -> begin
+    pushPS(popRS())
+    return NEXT
+end)
+
+RFETCH = defPrimWord("R@", () -> begin
+    pushPS(mem[reg.RSP])
+    return NEXT
+end)
+
+RSPFETCH = defPrimWord("RSP@", () -> begin
+    pushPS(reg.RSP)
+    return NEXT
+end)
+
+RSPSTORE = defPrimWord("RSP!", () -> begin
+    reg.RSP = popPS()
+    return NEXT
+end)
+
+RDROP = defPrimWord("RDROP", () -> begin
+    popRS()
+    return NEXT
+end)
+
+# Parameter Stack
+
+PSPFETCH = defPrimWord("PSP@", () -> begin
+    pushPS(reg.PSP)
+    return NEXT
+end)
+
+PSPSTORE = defPrimWord("PSP!", () -> begin
+    reg.PSP = popPS()
+    return NEXT
+end)
+
+# Working Register
+
+WFETCH = defPrimWord("W@", () -> begin
+    pushPS(reg.W)
+    return NEXT
+end)
+
+WSTORE = defPrimWord("W!", () -> begin
+    reg.W = popPS()
+    return NEXT
+end)
+
+# I/O
+
+sources = Array{Any,1}()
+currentSource() = sources[length(sources)]
+
+EOF = defPrimWord("\x04", () -> begin
+    close(pop!(sources))
+    if !isempty(sources)
+        return NEXT
+    else
+        return 0
+    end
+end)
+
+EMIT = defPrimWord("EMIT", () -> begin
+    print(Char(popPS()))
+    return NEXT
+end)
+
+SPAN, SPAN_CFA = defNewVar("SPAN", 0)
+EXPECT = defPrimWord("EXPECT", () -> begin
+    maxLen = popPS()
+    addr = popPS()
+
+    if !eof(currentSource())
+        line = chomp(readline(currentSource()))
+        mem[SPAN] = min(length(line), maxLen)
+        putString(line[1:mem[SPAN]], addr)
+    else
+        mem[SPAN] = 1
+        mem[addr] = 4 # eof
+    end
+
+    return NEXT
+end)
+
+BASE, BASE_CFA = defNewVar("BASE", 10)
+NUMBER = defPrimWord("NUMBER", () -> begin
+    wordAddr = popPS()+1
+    wordLen = mem[wordAddr-1]
+
+    s = getString(wordAddr, wordLen)
+
+    pushPS(parse(Int64, s, mem[BASE]))
+
+    return NEXT
+end)
+
+# Dictionary searches
+
+FIND = defPrimWord("FIND", () -> begin
+
+    countedAddr = popPS()
+    wordAddr = countedAddr + 1
+    wordLen = mem[countedAddr]
+    word = lowercase(getString(wordAddr, wordLen))
+
+    latest = LATEST
+    
+    i = 0
+    while (latest = mem[latest]) > 0
+        lenAndFlags = mem[latest+1]
+        len = lenAndFlags & F_LENMASK
+        hidden = (lenAndFlags & F_HIDDEN) == F_HIDDEN
+
+        if hidden || len != wordLen
+            continue
+        end
+        
+        thisAddr = latest+2
+        thisWord = lowercase(getString(thisAddr, len))
+
+        if lowercase(thisWord) == lowercase(word)
+            break
+        end
+    end
+
+    pushPS(latest)
+
+    return NEXT
+end)
+
+TOCFA = defPrimWord(">CFA", () -> begin
+
+    addr = popPS()
+    lenAndFlags = mem[addr+1]
+    len = lenAndFlags & F_LENMASK
+
+    pushPS(addr + 2 + len)
+
+    return NEXT
+end)
+
+TOPFA = defWord(">PFA", [TOCFA, INCR, EXIT])
+
+# Branching
+
+BRANCH = defPrimWord("BRANCH", () -> begin
+    reg.IP += mem[reg.IP]
+    return NEXT
+end)
+
+ZBRANCH = defPrimWord("0BRANCH", () -> begin
+    if (popPS() == 0)
+        reg.IP += mem[reg.IP]
     else
-        return false
+        reg.IP += 1
+    end
+
+    return NEXT
+end)
+
+# Strings
+
+LITSTRING = defPrimWord("LITSTRING", () -> begin
+    len = mem[reg.IP]
+    reg.IP += 1
+    pushPS(reg.IP)
+    pushPS(len)
+    reg.IP += len
+
+    return NEXT
+end)
+
+TYPE = defPrimWord("TYPE", () -> begin
+    len = popPS()
+    addr = popPS()
+    str = getString(addr, len)
+    print(str)
+    return NEXT
+end)
+
+# Outer interpreter
+
+TRACE = defPrimWord("TRACE", () -> begin
+    println("reg.W: $(reg.W) reg.IP: $(reg.IP)")
+    print("PS: "); printPS()
+    print("RS: "); printRS()
+    print("[paused]")
+    readline()
+
+    return NEXT
+end)
+
+COMMA = defPrimWord(",", () -> begin
+    mem[mem[HERE]] = popPS()
+    mem[HERE] += 1
+
+    return NEXT
+end)
+
+BTICK = defWord("[']",
+    [FROMR, DUP, INCR, TOR, FETCH, EXIT])
+
+EXECUTE = defPrimWord("EXECUTE", () -> begin
+    reg.W = popPS()
+    return mem[reg.W]
+end)
+
+TIB_CFA = defConst("TIB", TIB)
+NUMTIB, NUMTIB_CFA = defNewVar("#TIB", 0)
+TOIN, TOIN_CFA = defNewVar(">IN", 0)
+
+QUERY = defWord("QUERY",
+    [TIB_CFA, LIT, 160, EXPECT,
+    SPAN_CFA, FETCH, NUMTIB_CFA, STORE,
+    LIT, 0, TOIN_CFA, STORE,
+    EXIT])
+
+WORD = defPrimWord("WORD", () -> begin
+    delim = popPS()
+
+    # Chew up initial occurrences of delim
+    while (mem[TOIN]<mem[NUMTIB] && mem[TIB+mem[TOIN]] == delim)
+        mem[TOIN] += 1
+    end
+
+    countAddr = mem[HERE]
+    addr = mem[HERE]+1
+
+    # Start reading in word
+    count = 0
+    while (mem[TOIN]<mem[NUMTIB])
+        mem[addr] = mem[TIB+mem[TOIN]]
+        mem[TOIN] += 1
+
+        if (mem[addr] == delim)
+            break
+        end
+
+        count += 1
+        addr += 1
+    end
+
+    # Record count
+    mem[countAddr] = count
+    pushPS(countAddr)
+
+    return NEXT
+end)
+
+PARSE = defPrimWord("PARSE", () -> begin
+    delim = popPS()
+
+    # Chew up initial occurrences of delim
+    addr = mem[HERE]
+
+    # Start reading input stream
+    count = 0
+    while (mem[TOIN]<mem[NUMTIB])
+        mem[addr] = mem[TIB+mem[TOIN]]
+        mem[TOIN] += 1
+
+        if (mem[addr] == delim)
+            break
+        end
+
+        count += 1
+        addr += 1
+    end
+
+    pushPS(addr)
+    pushPS(count)
+
+    return NEXT
+end)
+
+BYE = defPrimWord("BYE", () -> begin
+    println("Bye!")
+    return 0
+end)
+
+STATE, STATE_CFA = defNewVar("STATE", 0)
+
+INTERPRET = defWord("INTERPRET",
+    [LIT, 32, WORD, # Read next space-delimited word
+
+    DUP, FETCH, ZE, ZBRANCH, 3,
+        DROP, EXIT, # Exit if TIB is exhausted
+
+    STATE_CFA, FETCH, ZBRANCH, 31,
+        # Compiling
+        DUP, FIND, QDUP, ZBRANCH, 19,
+
+            # Found word. 
+            SWAP, DROP,
+            DUP, TOCFA, SWAP, INCR, FETCH, LIT, F_IMMED, AND, ZBRANCH, 4,
+                # Immediate: Execute!
+                EXECUTE, BRANCH, -33,
+
+                # Not immediate: Compile!
+                COMMA, BRANCH, -36,
+
+            # No word found, parse number
+            NUMBER, BTICK, LIT, COMMA, COMMA, BRANCH, -43,
+        
+       # Interpreting
+        DUP, FIND, QDUP, ZBRANCH, 7,
+
+            # Found word. Execute!
+            SWAP, DROP, TOCFA, EXECUTE, BRANCH, -54,
+
+            # No word found, parse number and leave on stack
+            NUMBER, BRANCH, -57,
+    EXIT]
+)
+
+PROMPT = defPrimWord("PROMPT", () -> begin
+    if (mem[STATE] == 0 && currentSource() == STDIN)
+        println(" ok")
+    end
+
+    return NEXT
+end)
+
+QUIT = defWord("QUIT",
+    [LIT, 0, STATE_CFA, STORE,
+    LIT, 0, NUMTIB_CFA, STORE,
+    RSP0_CFA, RSPSTORE,
+    QUERY,
+    INTERPRET, PROMPT,
+    BRANCH,-4])
+
+ABORT = defWord("ABORT",
+    [PSP0_CFA, PSPSTORE, QUIT])
+
+INCLUDE = defPrimWord("INCLUDE", () -> begin
+    pushPS(32)
+    callPrim(mem[WORD])
+    wordAddr = popPS()+1
+    wordLen = mem[wordAddr-1]
+    word = getString(wordAddr, wordLen)
+
+    push!(sources, open(word, "r"))
+
+    # Clear input buffer
+    mem[NUMTIB] = 0
+
+    return NEXT
+end)
+
+# Compilation
+
+HEADER = defPrimWord("HEADER", () -> begin
+    wordAddr = popPS()+1
+    wordLen = mem[wordAddr-1]
+    word = getString(wordAddr, wordLen)
+
+    createHeader(word, 0)
+
+    return NEXT
+end)
+
+LBRAC = defPrimWord("[", () -> begin
+    mem[STATE] = 0
+    return NEXT
+end, flags=F_IMMED)
+
+RBRAC = defPrimWord("]", () -> begin
+    mem[STATE] = 1
+    return NEXT
+end, flags=F_IMMED)
+
+HIDDEN = defPrimWord("HIDDEN", () -> begin
+    addr = popPS() + 1
+    mem[addr] = mem[addr] $ F_HIDDEN
+    return NEXT
+end)
+
+HIDE = defWord("HIDE",
+    [LIT, 32, WORD,
+    FIND,
+    HIDDEN,
+    EXIT])
+
+COLON = defWord(":",
+    [LIT, 32, WORD,
+    HEADER,
+    LIT, DOCOL, COMMA,
+    LATEST_CFA, FETCH, HIDDEN,
+    RBRAC,
+    EXIT])
+
+SEMICOLON = defWord(";",
+    [LIT, EXIT, COMMA,
+    LATEST_CFA, FETCH, HIDDEN,
+    LBRAC,
+    EXIT], flags=F_IMMED)
+
+IMMEDIATE = defPrimWord("IMMEDIATE", () -> begin
+    lenAndFlagsAddr = mem[LATEST] + 1
+    mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
+    return NEXT
+end, flags=F_IMMED)
+
+
+#### VM loop ####
+
+initialized = false
+initFileName = nothing
+if isfile("lib.4th")
+    initFileName = "lib.4th"
+elseif isfile(Pkg.dir("forth/src/lib.4th"))
+    initFileName = Pkg.dir("forth/src/lib.4th")
+end
+
+function run(;initialize=true)
+    # Begin with STDIN as source
+    push!(sources, STDIN)
+
+    global initialized, initFileName
+    if !initialized && initialize
+        if initFileName != nothing
+            print("Including definitions from $initFileName...")
+            push!(sources, open(initFileName, "r"))
+            initialized = true
+        else
+            println("No library file found. Only primitive words available.")
+        end
+    end
+
+    # Start with IP pointing to first instruction of outer interpreter
+    reg.IP = QUIT + 1
+
+    # Primitive processing loop.
+    # Everyting else is simply a consequence of this loop!
+    jmp = NEXT
+    while jmp != 0
+        try
+            #println("Entering prim $(getPrimName(jmp))")
+            jmp = callPrim(jmp)
+
+        catch ex
+            showerror(STDOUT, ex)
+            println()
+
+            while !isempty(sources) && currentSource() != STDIN
+                close(pop!(sources))
+            end
+
+            # QUIT
+            reg.IP = ABORT + 1
+            jmp = NEXT
+        end
+    end
+end
+
+# Debugging tools
+
+function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
+    chars = Array{Char,1}(cellsPerLine)
+
+    lineStartAddr = cellsPerLine*div((startAddr-1),cellsPerLine) + 1
+    endAddr = startAddr + count - 1
+
+    q, r = divrem((endAddr-lineStartAddr+1), cellsPerLine)
+    numLines = q + (r > 0 ? 1 : 0)
+
+    i = lineStartAddr
+    for l in 1:numLines
+        print(i,":")
+
+        for c in 1:cellsPerLine
+            if i >= startAddr && i <= endAddr
+                print("\t",mem[i])
+                if mem[i]>=32 && mem[i]<128
+                    chars[c] = Char(mem[i])
+                else
+                    chars[c] = '.'
+                end
+            else
+                print("\t")
+                chars[c] = ' '
+            end
+
+            i += 1
+        end
+
+        println("\t", ASCIIString(chars))
     end
 end
-interpretNonPrimitive() = false
-interpretNumber() = false
 
-modes["interpret"] = () -> begin
-    getWordOrNewline()
+function printPS()
+    count = reg.PSP - PSP0
 
-    if ! (interpretPrimitive() ||
-        interpretNonPrimitive() ||
-        interpretNumber())
-        println("Error: unknown word '$word'.")
+    if count > 0
+        print("<$count>")
+        for i in (PSP0+1):reg.PSP
+            print(" $(mem[i])")
+        end
+        println()
+    else
+        println("Parameter stack empty")
     end
 end
 
-function repl()
+function printRS()
+    count = reg.RSP - RSP0
 
-    global mode = "interpret"
-    idx = 1
-    while mode != "stop"
-        modes[mode]()
+    if count > 0
+        print("<$count>")
+        for i in (RSP0+1):reg.RSP
+            print(" $(mem[i])")
+        end
+        println()
+    else
+        println("Return stack empty")
     end
 end
 
-# Bootstrapping interpreter
+DUMP = defPrimWord("DUMP", () -> begin
+    count = popPS()
+    addr = popPS()
 
-firstProg = """%J dict["\\n"] = () -> nothing
-%J dict["\\n"] = () -> nothing
-%J dict[""] = () -> global mode = "stop"
-%J global DS = []
-%J global RS = []
-"""
+    dump(addr, count=count)
 
-instream = IOBuffer(firstProg)
-repl()
+    return NEXT
+end)
 
 end