module forth
-
RS = Array{Int64, 1}(1024)
-RSP = 1
+RSP = 0
PS = Array{Int64, 1}(1024)
-PSP = 1
+PSP =0
IP = 0
W = 0
X = 0
-jmp = nothing
+jmp = 0
primitives = Array{Expr,1}()
-memory = Array{Int64,1}()
-headers = Array{Tuple{AbstractString, Int64},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 popRS()
+ global RSP
+ val = RS[RSP]
+ RSP -= 1
+ return val
+end
+
+function pushPS(val::Int64)
+ global PSP
+ PS[PSP += 1] = val
+end
+
+function popPS()
+ global PSP
+ val = PS[PSP]
+ PSP -= 1
+ return val
+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)
-function addPrim(name::AbstractString, expr::Expr)
push!(primitives, expr)
- push!(memory, -length(primitives))
- push!(headers, (name, length(memory)))
-
- return 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
-NEXT = addPrim("next", :(begin
+# Threading Primitives
+
+NEXT = defPrim("NEXT", :(begin
W = memory[IP]
IP += 1
X = memory[W]
- jmp = primitives[-X]
+ jmp = X
end))
-DOCOL = addPrim("docol", :(begin
- push!(RS, IP)
+DOCOL = defPrim("DOCOL", :(begin
+ pushRS(IP)
IP = W + 1
jmp = NEXT
end))
-EXIT = addPrim("exit", :(begin
- IP = pop!(RS)
+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
+
# VM loop
jmp = NEXT
function runVM()
while true
- eval(jmp)
+ eval(primitives[-memory[jmp]])
end
end