X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=src%2Fforth.jl;h=fb7121c27d13851b98c445e2daf7db1000219e4c;hb=87b17b0ee12c90f028186761fbb2bd5f6b4008eb;hp=8c5c3de153954ffcbedfbe49073d08952d776be1;hpb=ce55be3d16cf4ccb4284d323fc045b2afed20320;p=forth.jl.git

diff --git a/src/forth.jl b/src/forth.jl
index 8c5c3de..fb7121c 100644
--- a/src/forth.jl
+++ b/src/forth.jl
@@ -1,12 +1,12 @@
 module forth
 
 # VM mem size
-size_mem = 640*1024
+size_mem = 1000000 # 1 mega-int
 
 # Buffer sizes
-size_RS = 1024   # Return stack size
-size_PS = 1024   # Parameter stack size
-size_TIB = 1096  # Terminal input buffer size
+size_RS = 1000   # Return stack size
+size_PS = 1000   # Parameter stack size
+size_TIB = 1000  # Terminal input buffer size
 
 # The mem array constitutes the memory of the VM. It has the following geography:
 #
@@ -26,25 +26,24 @@ size_TIB = 1096  # Terminal input buffer size
 # the dictionary.
 #
 # Simple linear addressing is used with one exception: references to primitive code
-# blocks, which are represented as anonymous functions, appear the negative index
-# into the primitives array which contains only these functions.
+# blocks, which are represented as anonymous functions, appear as negative indicies
+# into the primitives array which contains these functions.
 
 mem = Array{Int64,1}(size_mem)
 primitives = Array{Function,1}()
+primNames = Array{ASCIIString,1}()
 
 # Built-in variables
 
 nextVarAddr = 1
-RSP0 = nextVarAddr; nextVarAddr += 1
-PSP0 = nextVarAddr; nextVarAddr += 1
 HERE = nextVarAddr; nextVarAddr += 1
 LATEST = nextVarAddr; nextVarAddr += 1
 
-mem[RSP0] = nextVarAddr              # bottom of RS
-mem[PSP0] = mem[RSP0] + size_RS      # bottom of PS
-TIB = mem[PSP0] + size_PS            # address of terminal input buffer
-mem[HERE] = TIB + size_TIB           # location of bottom of dictionary
-mem[LATEST] = 0                      # no previous definition
+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
 
@@ -54,26 +53,29 @@ type Reg
     PSP::Int64  # Parameter/data stack pointer
     IP::Int64   # Instruction pointer
     W::Int64    # Working register
-    X::Int64    # Extra register
 end
-reg = Reg(mem[RSP0], mem[PSP0], 0, 0, 0)
+reg = Reg(RSP0, PSP0, 0, 0)
 
-# Stack manipulation
+# Stack manipulation functions
 
-type StackUnderflow <: Exception end
+type ParamStackUnderflow <: Exception end
+type ReturnStackUnderflow <: Exception end
 
-getRSDepth() = reg.RSP - mem[RSP0]
-getPSDepth() = reg.PSP - mem[PSP0]
+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(StackUnderflow())
+        throw(ParamStackUnderflow())
     end
 end
 
 function ensureRSDepth(depth::Int64)
     if getRSDepth()<depth
-        throw(StackUnderflow())
+        throw(ReturnStackUnderflow())
     end
 end
 
@@ -101,552 +103,585 @@ function popPS()
     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"))
+
+    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
+        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
-    mem[mem[HERE]:(mem[HERE]+length(name)-1)] = [Int(c) for c in name]; mem[HERE] += length(name)
+    putString(name, mem[HERE]); mem[HERE] += length(name)
 end
 
-function defPrim(name::AbstractString, f::Function; flags::Int64=0)
+function defPrimWord(name::AbstractString, f::Function; flags::Int64=0)
     createHeader(name, flags)
 
     codeWordAddr = mem[HERE]
-    push!(primitives, f)
-    mem[codeWordAddr] = -length(primitives)
+    mem[codeWordAddr] = defPrim(f, name=name)
     mem[HERE] += 1
 
     return codeWordAddr
 end
 
-callPrim(addr::Int64) = primitives[-addr]()
+function defWord(name::AbstractString, wordAddrs::Array{Int64,1}; flags::Int64=0)
+    createHeader(name, flags)
+
+    addr = mem[HERE]
+    mem[mem[HERE]] = DOCOL
+    mem[HERE] += 1
+
+    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)
-    defPrim(name, eval(:(() -> begin
+
+    defPrimWord(name, eval(:(() -> begin
         pushPS($(varAddr))
-        return mem[NEXT]
+        return NEXT
     end)))
 end
 
 function defNewVar(name::AbstractString, initial::Int64; flags::Int64=0)
     createHeader(name, flags)
     
+    codeWordAddr = mem[HERE]
     varAddr = mem[HERE] + 1
-    push!(primitives, eval(:(() -> begin
-        pushPS($(varAddr))
-        return mem[NEXT]
-    end)))
-    mem[mem[HERE]] = -length(primitives); mem[HERE] += 1
 
+    mem[mem[HERE]] = DOVAR; mem[HERE] += 1
     mem[mem[HERE]] = initial; mem[HERE] += 1
 
-    return varAddr
+    return varAddr, codeWordAddr
 end
 
 function defConst(name::AbstractString, val::Int64; flags::Int64=0)
-    defPrim(name, eval(:(() -> begin
-        pushPS($(val))
-        return mem[NEXT]
-    end)))
-
-    return val
-end
-
-function defWord(name::AbstractString, wordAddrs::Array{Int64,1}; flags::Int64=0)
     createHeader(name, flags)
 
-    addr = mem[HERE]
-    mem[mem[HERE]] = mem[DOCOL]
-    mem[HERE] += 1
+    codeWordAddr = mem[HERE]
 
-    for wordAddr in wordAddrs
-        mem[mem[HERE]] = wordAddr
-        mem[HERE] += 1
-    end
+    mem[mem[HERE]] = DOCON; mem[HERE] += 1
+    mem[mem[HERE]] = val; mem[HERE] += 1
 
-    return addr
+    return codeWordAddr
 end
 
 # Threading Primitives (inner interpreter)
 
-NEXT = defPrim("NEXT", () -> begin
+NEXT = defPrim(() -> begin
     reg.W = mem[reg.IP]
     reg.IP += 1
     return mem[reg.W]
-end)
+end, name="NEXT")
 
-DOCOL = defPrim("DOCOL", () -> begin
+DOCOL = defPrim(() -> begin
     pushRS(reg.IP)
     reg.IP = reg.W + 1
-    return mem[NEXT]
-end)
+    return NEXT
+end, name="DOCOL")
+
+DOVAR = defPrim(() -> begin
+    pushPS(reg.W + 1)
+    return NEXT
+end, name="DOVAR")
 
-EXIT = defPrim("EXIT", () -> begin
+DOCON = defPrim(() -> begin
+    pushPS(mem[reg.W + 1])
+    return NEXT
+end, name="DOVAR")
+
+EXIT = defPrimWord("EXIT", () -> begin
     reg.IP = popRS()
-    return mem[NEXT]
+    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 = defPrim("DROP", () -> begin
+DROP = defPrimWord("DROP", () -> begin
     popPS()
-    return mem[NEXT]
+    return NEXT
 end)
 
-SWAP = defPrim("SWAP", () -> begin
+SWAP = defPrimWord("SWAP", () -> begin
     a = popPS()
     b = popPS()
     pushPS(a)
     pushPS(b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-DUP = defPrim("DUP", () -> begin
+DUP = defPrimWord("DUP", () -> begin
+    ensurePSDepth(1)
     pushPS(mem[reg.PSP])
-    return mem[NEXT]
+    return NEXT
 end)
 
-OVER = defPrim("OVER", () -> begin
+OVER = defPrimWord("OVER", () -> begin
     ensurePSDepth(2)
     pushPS(mem[reg.PSP-1])
-    return mem[NEXT]
+    return NEXT
 end)
 
-ROT = defPrim("ROT", () -> begin
+ROT = defPrimWord("ROT", () -> begin
     a = popPS()
     b = popPS()
     c = popPS()
+    pushPS(b)
     pushPS(a)
     pushPS(c)
-    pushPS(b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-NROT = defPrim("-ROT", () -> begin
+NROT = defPrimWord("-ROT", () -> begin
     a = popPS()
     b = popPS()
     c = popPS()
-    pushPS(b)
     pushPS(a)
     pushPS(c)
-    return mem[NEXT]
+    pushPS(b)
+    return NEXT
 end)
 
-TWODROP = defPrim("2DROP", () -> begin
+
+TWODROP = defPrimWord("2DROP", () -> begin
     popPS()
     popPS()
-    return mem[NEXT]
+    return NEXT
 end)
 
-TWODUP = defPrim("2DUP", () -> begin
+TWODUP = defPrimWord("2DUP", () -> begin
     ensurePSDepth(2)
     a = mem[reg.PSP-1]
     b = mem[reg.PSP]
     pushPS(a)
     pushPS(b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-TWOSWAP = defPrim("2SWAP", () -> begin
+TWOSWAP = defPrimWord("2SWAP", () -> begin
     a = popPS()
     b = popPS()
     c = popPS()
     d = popPS()
     pushPS(b)
     pushPS(a)
-    pushPS(c)
     pushPS(d)
-    return mem[NEXT]
+    pushPS(c)
+    return NEXT
 end)
 
-QDUP = defPrim("?DUP", () -> begin
+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 mem[NEXT]
+    return NEXT
 end)
 
-INCR = defPrim("1+", () -> begin
+INCR = defPrimWord("1+", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] += 1
-    return mem[NEXT]
+    return NEXT
 end)
 
-DECR = defPrim("1-", () -> begin
+DECR = defPrimWord("1-", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] -= 1
-    return mem[NEXT]
+    return NEXT
 end)
 
-INCR2 = defPrim("2+", () -> begin
+INCR2 = defPrimWord("2+", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] += 2
-    return mem[NEXT]
+    return NEXT
 end)
 
-DECR2 = defPrim("2-", () -> begin
+DECR2 = defPrimWord("2-", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] -= 2
-    return mem[NEXT]
+    return NEXT
 end)
 
-ADD = defPrim("+", () -> begin
+ADD = defPrimWord("+", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a+b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-SUB = defPrim("-", () -> begin
+SUB = defPrimWord("-", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a-b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-MUL = defPrim("*", () -> begin
+MUL = defPrimWord("*", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a*b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-DIVMOD = defPrim("/MOD", () -> begin
+DIVMOD = defPrimWord("/MOD", () -> begin
     b = popPS()
     a = popPS()
     q,r = divrem(a,b)
     pushPS(r)
     pushPS(q)
-    return mem[NEXT]
+    return NEXT
+end)
+
+TWOMUL = defPrimWord("2*", () -> begin
+    pushPS(popPS() << 1)
+    return NEXT
+end)
+
+TWODIV = defPrimWord("2/", () -> begin
+    pushPS(popPS() >> 1)
+    return NEXT
 end)
 
-EQU = defPrim("=", () -> begin
+EQ = defPrimWord("=", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a==b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-NEQU = defPrim("<>", () -> begin
+NE = defPrimWord("<>", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a!=b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-LT = defPrim("<", () -> begin
+LT = defPrimWord("<", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a<b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-GT = defPrim(">", () -> begin
+GT = defPrimWord(">", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a>b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-LE = defPrim("<=", () -> begin
+LE = defPrimWord("<=", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a<=b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-GE = defPrim(">=", () -> begin
+GE = defPrimWord(">=", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a>=b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZEQU = defPrim("0=", () -> begin
+ZE = defPrimWord("0=", () -> begin
     pushPS(popPS() == 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZNEQU = defPrim("0<>", () -> begin
+ZNE = defPrimWord("0<>", () -> begin
     pushPS(popPS() != 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZLT = defPrim("0<", () -> begin
+ZLT = defPrimWord("0<", () -> begin
     pushPS(popPS() < 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZGT = defPrim("0>", () -> begin
+ZGT = defPrimWord("0>", () -> begin
     pushPS(popPS() > 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZLE = defPrim("0<=", () -> begin
+ZLE = defPrimWord("0<=", () -> begin
     pushPS(popPS() <= 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZGE = defPrim("0>=", () -> begin
+ZGE = defPrimWord("0>=", () -> begin
     pushPS(popPS() >= 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-AND = defPrim("AND", () -> begin
+AND = defPrimWord("AND", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a & b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-OR = defPrim("OR", () -> begin
+OR = defPrimWord("OR", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a | b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-XOR = defPrim("XOR", () -> begin
+XOR = defPrimWord("XOR", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a $ b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-INVERT = defPrim("INVERT", () -> begin
+INVERT = defPrimWord("INVERT", () -> begin
     pushPS(~popPS())
-    return mem[NEXT]
+    return NEXT
 end)
 
 # Literals
 
-LIT = defPrim("LIT", () -> begin
+LIT = defPrimWord("LIT", () -> begin
     pushPS(mem[reg.IP])
     reg.IP += 1
-    return mem[NEXT]
+    return NEXT
 end)
 
 # Memory primitives
 
-STORE = defPrim("!", () -> begin
+STORE = defPrimWord("!", () -> begin
     addr = popPS()
     dat = popPS()
     mem[addr] = dat
-    return mem[NEXT]
+    return NEXT
 end)
 
-FETCH = defPrim("@", () -> begin
+FETCH = defPrimWord("@", () -> begin
     addr = popPS()
     pushPS(mem[addr])
-    return mem[NEXT]
+    return NEXT
 end)
 
-ADDSTORE = defPrim("+!", () -> begin
+ADDSTORE = defPrimWord("+!", () -> begin
     addr = popPS()
     toAdd = popPS()
     mem[addr] += toAdd
-    return mem[NEXT]
+    return NEXT
 end)
 
-SUBSTORE = defPrim("-!", () -> begin
+SUBSTORE = defPrimWord("-!", () -> begin
     addr = popPS()
     toSub = popPS()
     mem[addr] -= toSub
-    return mem[NEXT]
+    return NEXT
 end)
 
 
-# Built-in variables
-
-defExistingVar("HERE", HERE)
-defExistingVar("LATEST", LATEST)
-defExistingVar("PSP0", PSP0)
-defExistingVar("RSP0", RSP0)
-STATE = defNewVar("STATE", 0)
-BASE = defNewVar("BASE", 10)
-
-# Constants
-
-defConst("VERSION", 1)
-defConst("DOCOL", DOCOL)
-defConst("DICT", DICT)
-F_IMMED = defConst("F_IMMED", 128)
-F_HIDDEN = defConst("F_HIDDEN", 256)
-F_LENMASK = defConst("F_LENMASK", 127)
-
 # Return Stack
 
-TOR = defPrim(">R", () -> begin
+TOR = defPrimWord(">R", () -> begin
     pushRS(popPS())
-    return mem[NEXT]
+    return NEXT
 end)
 
-FROMR = defPrim("R>", () -> begin
+FROMR = defPrimWord("R>", () -> begin
     pushPS(popRS())
-    return mem[NEXT]
+    return NEXT
+end)
+
+RFETCH = defPrimWord("R@", () -> begin
+    pushPS(mem[reg.RSP])
+    return NEXT
 end)
 
-RSPFETCH = defPrim("RSP@", () -> begin
+RSPFETCH = defPrimWord("RSP@", () -> begin
     pushPS(reg.RSP)
-    return mem[NEXT]
+    return NEXT
 end)
 
-RSPSTORE = defPrim("RSP!", () -> begin
-    RSP = popPS()
-    return mem[NEXT]
+RSPSTORE = defPrimWord("RSP!", () -> begin
+    reg.RSP = popPS()
+    return NEXT
 end)
 
-RDROP = defPrim("RDROP", () -> begin
+RDROP = defPrimWord("RDROP", () -> begin
     popRS()
-    return mem[NEXT]
+    return NEXT
 end)
 
 # Parameter Stack
 
-PSPFETCH = defPrim("PSP@", () -> begin
+PSPFETCH = defPrimWord("PSP@", () -> begin
     pushPS(reg.PSP)
-    return mem[NEXT]
+    return NEXT
 end)
 
-PSPSTORE = defPrim("PSP!", () -> begin
-    PSP = popPS()
-    return mem[NEXT]
+PSPSTORE = defPrimWord("PSP!", () -> begin
+    reg.PSP = popPS()
+    return NEXT
 end)
 
-# I/O
-
-defConst("TIB", TIB)
-NUMTIB = defNewVar("#TIB", 0)
-TOIN = defNewVar(">IN", 0)
-
-KEY = defPrim("KEY", () -> begin
-    if mem[TOIN] >= mem[NUMTIB]
-        mem[TOIN] = 0
-        line = readline()
-        mem[NUMTIB] = length(line)
-        mem[TIB:(TIB+mem[NUMTIB]-1)] = [Int64(c) for c in collect(line)]
-    end
-
-    pushPS(mem[TIB + mem[TOIN]])
-    mem[TOIN] += 1
+# Working Register
 
-    return mem[NEXT]
+WFETCH = defPrimWord("W@", () -> begin
+    pushPS(reg.W)
+    return NEXT
 end)
 
-EMIT = defPrim("EMIT", () -> begin
-    print(Char(popPS()))
-    return mem[NEXT]
+WSTORE = defPrimWord("W!", () -> begin
+    reg.W = popPS()
+    return NEXT
 end)
 
-WORD = defPrim("WORD", () -> begin
-    
-    c = -1
-
-    skip_to_end = false
-    while true
-
-        callPrim(mem[KEY])
-        c = Char(popPS())
-
-        if c == '\\'
-            skip_to_end = true
-            continue
-        end
+# I/O
 
-        if skip_to_end
-            if c == '\n'
-                skip_to_end = false
-            end
-            continue
-        end
+sources = Array{Any,1}()
+currentSource() = sources[length(sources)]
 
-        if c == ' ' || c == '\t'
-            continue
-        end
-
-        break
+EOF = defPrimWord("\x04", () -> begin
+    close(pop!(sources))
+    if !isempty(sources)
+        return NEXT
+    else
+        return 0
     end
+end)
 
-    wordAddr = mem[HERE]
-    offset = 0
-
-    while true
-        mem[wordAddr + offset] = Int64(c)
-        offset += 1
+EMIT = defPrimWord("EMIT", () -> begin
+    print(Char(popPS()))
+    return NEXT
+end)
 
-        callPrim(mem[KEY])
-        c = Char(popPS())
+SPAN, SPAN_CFA = defNewVar("SPAN", 0)
+EXPECT = defPrimWord("EXPECT", () -> begin
+    maxLen = popPS()
+    addr = popPS()
 
-        if c == ' ' || c == '\t' || c == '\n'
-            break
-        end
+    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
 
-    wordLen = offset
-
-    pushPS(wordAddr)
-    pushPS(wordLen)
-
-    return mem[NEXT]
+    return NEXT
 end)
 
-NUMBER = defPrim("NUMBER", () -> begin
-
-    wordLen = popPS()
-    wordAddr = popPS()
+BASE, BASE_CFA = defNewVar("BASE", 10)
+NUMBER = defPrimWord("NUMBER", () -> begin
+    wordAddr = popPS()+1
+    wordLen = mem[wordAddr-1]
 
-    s = ASCIIString([Char(c) for c in mem[wordAddr:(wordAddr+wordLen-1)]])
+    s = getString(wordAddr, wordLen)
 
-    try
-        pushPS(parse(Int64, s, mem[BASE]))
-        pushPS(0)
-    catch
-        pushPS(1) # Error indication
-    end
+    pushPS(parse(Int64, s, mem[BASE]))
 
-    return mem[NEXT]
+    return NEXT
 end)
 
 # Dictionary searches
 
-FIND = defPrim("FIND", () -> begin
+FIND = defPrimWord("FIND", () -> begin
 
-    wordLen = popPS()
-    wordAddr = popPS()
-    word = ASCIIString([Char(c) for c in mem[wordAddr:(wordAddr+wordLen-1)]])
+    countedAddr = popPS()
+    wordAddr = countedAddr + 1
+    wordLen = mem[countedAddr]
+    word = lowercase(getString(wordAddr, wordLen))
 
-    latest = mem[LATEST]
+    latest = LATEST
     
-    while latest>0
+    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
-            latest = mem[latest]
             continue
         end
         
         thisAddr = latest+2
-        thisWord = ASCIIString([Char(c) for c in mem[thisAddr:(thisAddr+len-1)]])
+        thisWord = lowercase(getString(thisAddr, len))
 
-        if thisWord == word
+        if lowercase(thisWord) == lowercase(word)
             break
         end
     end
 
     pushPS(latest)
 
-    return mem[NEXT]
+    return NEXT
 end)
 
-TOCFA = defPrim(">CFA", () -> begin
+TOCFA = defPrimWord(">CFA", () -> begin
 
     addr = popPS()
     lenAndFlags = mem[addr+1]
@@ -654,82 +689,321 @@ TOCFA = defPrim(">CFA", () -> begin
 
     pushPS(addr + 2 + len)
 
-    return mem[NEXT]
+    return NEXT
 end)
 
-TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
+TOPFA = defWord(">PFA", [TOCFA, INCR, EXIT])
 
-# Compilation
+# Branching
 
-CREATE = defPrim("CREATE", () -> begin
+BRANCH = defPrimWord("BRANCH", () -> begin
+    reg.IP += mem[reg.IP]
+    return NEXT
+end)
 
-    wordLen = popPS()
-    wordAddr = popPS()
-    word = ASCIIString([Char(c) for c in mem[wordAddr:(wordAddr+wordLen-1)]])
+ZBRANCH = defPrimWord("0BRANCH", () -> begin
+    if (popPS() == 0)
+        reg.IP += mem[reg.IP]
+    else
+        reg.IP += 1
+    end
 
-    mem[mem[HERE]] = mem[LATEST]; mem[HERE] += 1
-    mem[LATEST] = mem[HERE]
-    mem[mem[HERE]] = wordLen; mem[HERE] += 1
+    return NEXT
+end)
 
-    mem[mem[HERE]:(mem[HERE]+wordLen-1)] = collect(Int64, word)
-    mem[HERE] += wordLen
+# Strings
 
-    return mem[NEXT]
+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 = defPrim(",", () -> begin
+COMMA = defPrimWord(",", () -> begin
     mem[mem[HERE]] = popPS()
     mem[HERE] += 1
 
-    return mem[NEXT]
+    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)
 
-LBRAC = defPrim("[", () -> begin
+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 mem[NEXT]
-end, flags=F_IMMEDIATE)
+    return NEXT
+end, flags=F_IMMED)
 
-RBRAC = defPrim("]", () -> begin
+RBRAC = defPrimWord("]", () -> begin
     mem[STATE] = 1
-    return mem[NEXT]
-end, flags=F_IMMEDIATE)
+    return NEXT
+end, flags=F_IMMED)
 
-HIDDEN = defPrim("HIDDEN", () -> begin
+HIDDEN = defPrimWord("HIDDEN", () -> begin
     addr = popPS() + 1
     mem[addr] = mem[addr] $ F_HIDDEN
-    reurn mem[NEXT]
+    return NEXT
 end)
 
 HIDE = defWord("HIDE",
-    [WORD,
+    [LIT, 32, WORD,
     FIND,
     HIDDEN,
     EXIT])
 
 COLON = defWord(":",
-    [WORD,
-    CREATE,
+    [LIT, 32, WORD,
+    HEADER,
     LIT, DOCOL, COMMA,
-    LATEST, FETCH, HIDDEN,
+    LATEST_CFA, FETCH, HIDDEN,
     RBRAC,
     EXIT])
 
 SEMICOLON = defWord(";",
     [LIT, EXIT, COMMA,
-    LATEST, FETCH, HIDDEN,
+    LATEST_CFA, FETCH, HIDDEN,
     LBRAC,
-    EXIT], flags=F_IMMEDIATE)
+    EXIT], flags=F_IMMED)
 
-IMMEDIATE = defPrim("IMMEDIATE", () -> begin
+IMMEDIATE = defPrimWord("IMMEDIATE", () -> begin
     lenAndFlagsAddr = mem[LATEST] + 1
-    mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMEDIATE
-    return mem[NEXT]
-end, flags=F_IMMEDIATE)
+    mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
+    return NEXT
+end, flags=F_IMMED)
+
 
 #### VM loop ####
-function runVM()
+
+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 = callPrim(jmp)) != 0 end
+    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
@@ -737,32 +1011,42 @@ end
 function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
     chars = Array{Char,1}(cellsPerLine)
 
-    for i in 0:(count-1)
-        addr = startAddr + i
-        if i%cellsPerLine == 0
-            print("$addr:")
-        end
-
-        print("\t$(mem[addr]) ")
+    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
 
-        if (mem[addr]>=32 && mem[addr]<176)
-            chars[i%cellsPerLine + 1] = Char(mem[addr])
-        else
-            chars[i%cellsPerLine + 1] = '.'
+            i += 1
         end
 
-        if i%cellsPerLine == cellsPerLine-1
-            println(string("\t", ASCIIString(chars)))
-        end
+        println("\t", ASCIIString(chars))
     end
 end
 
 function printPS()
-    count = reg.PSP - mem[PSP0]
+    count = reg.PSP - PSP0
 
     if count > 0
         print("<$count>")
-        for i in (mem[PSP0]+1):reg.PSP
+        for i in (PSP0+1):reg.PSP
             print(" $(mem[i])")
         end
         println()
@@ -772,11 +1056,11 @@ function printPS()
 end
 
 function printRS()
-    count = reg.RSP - mem[RSP0]
+    count = reg.RSP - RSP0
 
     if count > 0
         print("<$count>")
-        for i in (mem[RSP0]+1):reg.RSP
+        for i in (RSP0+1):reg.RSP
             print(" $(mem[i])")
         end
         println()
@@ -785,4 +1069,13 @@ function printRS()
     end
 end
 
+DUMP = defPrimWord("DUMP", () -> begin
+    count = popPS()
+    addr = popPS()
+
+    dump(addr, count=count)
+
+    return NEXT
+end)
+
 end