On to constants.

[forth.jl.git] / src / forth.jl

diff --git a/src/forth.jl b/src/forth.jl
index 46c3c9c..f35d212 100644 (file)
--- a/src/forth.jl
+++ b/src/forth.jl
@@ -1,52 +1,163 @@
 module forth
 
-currentLine = ""
-currentPos = 0
-
-function nextLine()
-    if eof(STDIN)
-        return false
-    else
-        currentLine = readLine()
-        currentPos = 1
-        return true
-    end
+RS = Array{Int64, 1}(1024)
+RSP = 0
+
+PS = Array{Int64, 1}(1024)
+PSP =0
+
+IP = 0
+W = 0
+X = 0
+
+jmp = 0
+
+primitives = Array{Expr,1}()
+memory = Array{Int64,1}(64*1024)
+LATEST = 0
+HERE = 1
+
+# Intperpreter state
+
+STATE = 0
+
+# Current radix
+
+BASE = 10
+
+# Stack manipulation macros
+
+function pushRS(val::Int64)
+    global RSP
+    RS[RSP += 1] = val
 end
 
-function readPattern(pattern::Regex)
-    m = match(pattern, currentLine)
-    pos += length(m.match)
-    return m.match
+function popRS()
+    global RSP
+    val = RS[RSP]
+    RSP -= 1
+    return val
 end
 
-modes = Dict{AbstractString,Function}()
-mode = ""
+function pushPS(val::Int64)
+    global PSP
+    PS[PSP += 1] = val
+end
 
-function interpretPrimitive()
-    if haskey(dict, word)
-        dict[word]()
-        return true
-    else
-        return false
+function popPS()
+    global PSP
+    val = PS[PSP]
+    PSP -= 1
+    return val
 end
-interpretNonPrimitive() = false
-interpretNumber() = false
 
-modes["interpret"] = () -> begin
-    getWord()
-    
-    if ! (interpretPrimitive() ||
-        interpretNonPrimitive() ||
-        interpretNumber())
-        println("Error: unknown word '$word'.")
-    end
+# Primitive creation functions
+
+function defPrim(name::AbstractString, expr::Expr)
+    global HERE, LATEST
+
+    memory[HERE] = LATEST
+    LATEST = HERE
+    HERE += 1
+
+    memory[HERE] = length(name); HERE += 1
+    memory[HERE:(HERE+length(name)-1)] = [Int(c) for c in name]; HERE += length(name)
+
+    push!(primitives, expr)
+    memory[HERE] = -length(primitives)
+    codeword = HERE
+    HERE += 1
+
+    return codeword
+end
+
+function defVar(name::AbstractString, var::Expr)
+    defPrim(name, Expr(:call, :pushPS, var))
 end
 
-function repl()
+# Threading Primitives
+
+NEXT = defPrim("NEXT", :(begin
+    W = memory[IP]
+    IP += 1
+    X = memory[W]
+    jmp = X
+end))
+
+DOCOL = defPrim("DOCOL", :(begin
+    pushRS(IP)
+    IP = W + 1
+    jmp = NEXT
+end))
+
+EXIT = defPrim("EXIT", :(begin
+    IP = popRS()
+    jmp = NEXT
+end))
+
+
+# Basic forth primitives
+
+DROP = defPrim("DROP", :(begin
+    popPS()
+end))
+
+SWAP = defPrim("SWAP", :(begin
+    PS[PSP], PS[PSP-1] = PS[PSP-1], PS[PS]
+end))
+
+DUP = defPrim("DUP", :(begin
+    pushPS(PS[PSP])
+end))
+
+LIT = defPrim("LIT", :(begin
+    pushPS(memory[IP])
+    IP += 1
+end))
+
+# Memory primitives
+
+STORE = defPrim("!", :(begin
+    addr = popPS()
+    dat = popPS()
+    memory[addr] = dat
+end))
+
+FETCH = defPrim("@", :(begin
+    addr = popPS()
+    pushPS(memory[addr])
+end))
+
+ADDSTORE = defPrim("+!", :(begin
+    addr = popPS()
+    toAdd = popPS()
+    memory[addr] += toAdd
+end))
+
+SUBSTORE = defPrim("-!", :(begin
+    addr = popPS()
+    toSub = popPS()
+    memory[addr] -= toSub
+end))
+
+
+# Built-in variables
+
+defVar("STATE", :STATE)
+defVar("HERE", :HERE)
+defVar("LATEST", :LATEST)
+defVAR("PSP", :PSP)
+defVAR("BASE", :BASE)
+
+# Constants
+
+
 
-    mode = "interpret"
-    while mode != "stop"
-        modes[mode]()
+# VM loop
+jmp = NEXT
+function runVM()
+    while true
+        eval(primitives[-memory[jmp]])
     end
 end