module forth
-RS = Array{Int64, 1}(1024)
-RSP = 0
+# VM memory size
+size_memory = 640*1024
+
+# Buffer sizes
+size_RS = 1024 # Return stack size
+size_PS = 1024 # Parameter stack size
+size_TIB = 4096 # Terminal input buffer size
+
+# VM registers
+RSP = 0 # Return stack pointer
+PSP =0 # Parameter/data stack pointer
+IP = 0 # Instruction pointer
+W = 0 # Working register
+X = 0 # Extra register
+
+RSP0 = 1
+PSP0 = RSP0 + size_RS
+here = PSP0 + size_PS + size_TIB # location of bottom of dictionary
+latest = 0 # no previous definition
+
+# The following array constitutes the memory of the VM. It has the following geography:
+#
+# memory = +-----------------------+
+# | 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 the negative index
+# into the primitives array which contains only these functions.
+
+memory = Array{Int64,1}(size_memory)
+primitives = Array{Function,1}()
-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
-
-# Input buffer
-
-tib_size = 4096
-tib = length(memory) - tib_size
-numtib = 0
-toin = 0
# Stack manipulation functions
function pushRS(val::Int64)
global RSP
- RS[RSP += 1] = val
+ memory[RSP+=1] = val
end
function popRS()
global RSP
- val = RS[RSP]
+ val = memory[RSP]
RSP -= 1
return val
end
function pushPS(val::Int64)
global PSP
- PS[PSP += 1] = val
+ memory[PSP += 1] = val
end
function popPS()
# Primitive creation and calling functions
-function defPrim(name::AbstractString, expr::Expr)
- global HERE, LATEST
+function defPrim(name::AbstractString, f::Function)
+ global latest, here
- memory[HERE] = LATEST
- LATEST = HERE
- HERE += 1
+ 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)
+ 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)
- HERE += 1
+ push!(primitives, f)
+ memory[here] = -length(primitives)
+ here += 1
return -length(primitives)
end
-defVar(name::AbstractString, var::Symbol) = defPrim(name, quote
- pushPS($var)
- jmp = NEXT
-end)
+callPrim(addr::Int64) = primitives[-addr]()
-defConst(name::AbstractString, val::Int64) = defPrim(name, quote
- pushPS($val)
- jmp = Next
-end)
+function defVar(name::AbstractString, val::Int64)
+ global latest, here
+
+ 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, () -> begin
-callPrim(addr::Int64) = eval(primitives[-addr])
+ end)
+
+ pushPS($var)
+ jmp = NEXT
+end
# Threading Primitives
-NEXT = defPrim("NEXT", quote
+NEXT = defPrim("NEXT", () -> begin
W = memory[IP]
IP += 1
X = memory[W]
- jmp = X
+ return X
end)
-DOCOL = defPrim("DOCOL", quote
+DOCOL = defPrim("DOCOL", () -> begin
pushRS(IP)
IP = W + 1
- jmp = NEXT
+ return NEXT
end)
-EXIT = defPrim("EXIT", quote
+EXIT = defPrim("EXIT", () -> begin
IP = popRS()
- jmp = NEXT
+ return NEXT
end)
# Basic forth primitives
-DROP = defPrim("DROP", quote
+DROP = defPrim("DROP", () -> begin
popPS()
- jmp = NEXT
+ return NEXT
end)
-SWAP = defPrim("SWAP", quote
+SWAP = defPrim("SWAP", () -> begin
PS[PSP], PS[PSP-1] = PS[PSP-1], PS[PS]
- jmp = NEXT
+ return NEXT
end)
-DUP = defPrim("DUP", quote
+DUP = defPrim("DUP", () -> begin
pushPS(PS[PSP])
- jmp = NEXT
+ return NEXT
end)
-LIT = defPrim("LIT", quote
+LIT = defPrim("LIT", () -> begin
pushPS(memory[IP])
IP += 1
- jmp = NEXT
+ return NEXT
end)
# Memory primitives
addr = popPS()
dat = popPS()
memory[addr] = dat
- jmp = NEXT
+ return NEXT
end)
FETCH = defPrim("@", quote
addr = popPS()
pushPS(memory[addr])
- jmp = NEXT
+ return NEXT
end)
ADDSTORE = defPrim("+!", quote
addr = popPS()
toAdd = popPS()
memory[addr] += toAdd
- jmp = NEXT
+ return NEXT
end)
SUBSTORE = defPrim("-!", quote
addr = popPS()
toSub = popPS()
memory[addr] -= toSub
- jmp = NEXT
+ return NEXT
end)
# Return Stack
-TOR = defPrim(">R", quote
+TOR = defPrim(">R", () -> begin
pushRS(popPS())
- jmp = NEXT
+ return NEXT
end)
-FROMR = defPrim("R>", quote
+FROMR = defPrim("R>", () -> begin
pushPS(popRS())
+ return NEXT
end)
-RSPFETCH = defPrim("RSP@", quote
+RSPFETCH = defPrim("RSP@", () -> begin
pushPS(RSP)
- jmp = NEXT
+ return NEXT
end)
-RSPSTORE = defPrim("RSP!", quote
+RSPSTORE = defPrim("RSP!", () -> begin
RSP = popPS()
- jmp = NEXT
+ return NEXT
end)
-RDROP = defPrim("RDROP", quote
+RDROP = defPrim("RDROP", () -> begin
popRS()
- jmp = NEXT
+ return NEXT
end)
# Parameter Stack
-PSPFETCH = defPrim("PSP@", quote
+PSPFETCH = defPrim("PSP@", () -> begin
pushPS(PSP)
- jmp = NEXT
+ return NEXT
end)
-PSPSTORE = defPrim("PSP!", quote
+PSPSTORE = defPrim("PSP!", () -> begin
PSP = popPS()
- jmp = NEXT
+ return NEXT
end)
# I/O
defVar("#TIB", :numtib)
defVar(">IN", :toin)
-KEY = defPrim("KEY", quote
+KEY = defPrim("KEY", () -> begin
if toin >= numtib
end
- jmp = NEXT
+ return NEXT
end)
-EMIT = defPrim("EMIT", quote
+EMIT = defPrim("EMIT", () -> begin
- jmp = NEXT
+ return NEXT
end)
-WORD = defPrim("WORD", quote
+WORD = defPrim("WORD", () -> begin
- jmp = NEXT
+ return NEXT
end)
-NUMBER = defPrim("NUMBER", quote
+NUMBER = defPrim("NUMBER", () -> begin
- jmp = NEXT
+ return NEXT
end)
#### VM loop ####
-jmp = NEXT
function runVM()
- while true
- callPrim(jmp)
- end
+ jmp = NEXT
+ while (jmp = callPrim(jmp)) != 0 end
end
end
The Lambda Lab / projects / forth.jl.git / commitdiff