-module FORTH
+module forth
-function input(prompt::AbstractString="")
- print(prompt)
- strip(readline)
+# VM memory size
+size_memory = 640*1024
+
+# Buffer sizes
+size_SysVar = 16 #
+size_RS = 1024 # Return stack size
+size_PS = 1024 # Parameter stack size
+size_TIB = 4096 # Terminal input buffer size
+
+# VM registers
+type Reg
+ RSP::Int64 # Return stack pointer
+ PSP::Int64 # Parameter/data stack pointer
+ IP::Int64 # Instruction pointer
+ W::Int64 # Working register
+ X::Int64 # Extra register
+end
+
+# The following array constitutes the memory of the VM. It has the following geography:
+#
+# memory = +-----------------------+
+# | 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. Additionally, all
+#
+# 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}()
+
+# Built-in variables
+
+nextVarAddr = 1
+RSP0 = nextVarAddr; nextVarAddr += 1
+PSP0 = nextVarAddr; nextVarAddr += 1
+HERE = nextVarAddr; nextVarAddr += 1
+LATEST = nextVarAddr; nextVarAddr += 1
+
+memory[RSP0] = size_BIVar # bottom of RS
+memory[PSP0] = memory[RSP0] + size_RS # bottom of PS
+TIB = memory[PSP0] + size_PS # address of terminal input buffer
+memory[HERE] = TIB + size_TIB # location of bottom of dictionary
+memory[LATEST] = 0 # no previous definition
+
+
+# Stack manipulation functions
+
+function pushRS(reg::Reg, val::Int64)
+ memory[reg.RSP+=1] = val
+end
+
+function popRS(reg::Reg)
+ val = memory[reg.RSP]
+ reg.RSP -= 1
+ return val
+end
+
+function pushPS(reg::Reg, val::Int64)
+ memory[reg.PSP += 1] = val
+end
+
+function popPS(reg::Reg)
+ val = memory[reg.PSP]
+ reg.PSP -= 1
+ return val
end
-dictCore = Set{AbstractString}([
- "bye"
-])
+# Primitive creation and calling functions
-function coreEval(word::AbstractString)
- if word == "bye"
+function defPrim(name::AbstractString, f::Function)
+ 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, f)
+ memory[here] = -length(primitives)
+ here += 1
+
+ return -length(primitives)
end
-function repl()
+callPrim(reg::Reg, addr::Int64) = primitives[-addr](reg)
+
+function defSysVar(name::AbstractString, varAddr::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, eval(:((reg::Reg) -> begin
+ pushPS(reg, $(varAddr))
+ return NEXT
+ end)))
+ memory[here] = -length(primitives)
+ here += 1
+
+ return varAddr
+end
+
+defConst(name::AbstractString, val::Int64) = defSysVar(name, val)
+
+# Threading Primitives
+
+NEXT = defPrim("NEXT", (reg) -> begin
+ reg.W = memory[reg.IP]
+ reg.IP += 1
+ X = memory[reg.W]
+ return X
+end)
+
+DOCOL = defPrim("DOCOL", (reg) -> begin
+ pushRS(reg, reg.IP)
+ reg.IP = reg.W + 1
+ return NEXT
+end)
+
+EXIT = defPrim("EXIT", (reg) -> begin
+ reg.IP = popRS(reg)
+ return NEXT
+end)
+
+
+# Basic forth primitives
- while true
- line = input()
+DROP = defPrim("DROP", (reg) -> begin
+ popPS(reg)
+ return NEXT
+end)
+
+SWAP = defPrim("SWAP", (reg) -> begin
+ memory[reg.PSP], memory[reg.PSP-1] = memory[reg.PSP-1], memory[reg.PSP]
+ return NEXT
+end)
+
+DUP = defPrim("DUP", (reg) -> begin
+ pushPS(reg, memory[reg.PSP])
+ return NEXT
+end)
+
+LIT = defPrim("LIT", (reg) -> begin
+ pushPS(reg, memory[reg.IP])
+ reg.IP += 1
+ return NEXT
+end)
+
+# Memory primitives
+
+STORE = defPrim("!", (reg) -> begin
+ addr = popPS(reg)
+ dat = popPS(reg)
+ memory[addr] = dat
+ return NEXT
+end)
+
+FETCH = defPrim("@", (reg) -> begin
+ addr = popPS(reg)
+ pushPS(reg, memory[addr])
+ return NEXT
+end)
+
+ADDSTORE = defPrim("+!", (reg) -> begin
+ addr = popPS(reg)
+ toAdd = popPS(reg)
+ memory[addr] += toAdd
+ return NEXT
+end)
+
+SUBSTORE = defPrim("-!", (reg) -> begin
+ addr = popPS(reg)
+ toSub = popPS(reg)
+ memory[addr] -= toSub
+ return NEXT
+end)
+
+
+# Built-in variables
+
+
+# Constants
+
+defConst("VERSION", 1)
+defConst("DOCOL", DOCOL)
+
+# Return Stack
+
+TOR = defPrim(">R", (reg) -> begin
+ pushRS(reg, popPS(reg))
+ return NEXT
+end)
+
+FROMR = defPrim("R>", (reg) -> begin
+ pushPS(reg, popRS(reg))
+ return NEXT
+end)
+
+RSPFETCH = defPrim("RSP@", (reg) -> begin
+ pushPS(reg, RSP)
+ return NEXT
+end)
+
+RSPSTORE = defPrim("RSP!", (reg) -> begin
+ RSP = popPS(reg)
+ return NEXT
+end)
+
+RDROP = defPrim("RDROP", (reg) -> begin
+ popRS(reg)
+ return NEXT
+end)
+
+# Parameter Stack
+
+PSPFETCH = defPrim("PSP@", (reg) -> begin
+ pushPS(reg, PSP)
+ return NEXT
+end)
+
+PSPSTORE = defPrim("PSP!", (reg) -> begin
+ PSP = popPS(reg)
+ return NEXT
+end)
+
+# I/O
+
+defConst("TIB", tib)
+defVar("#TIB", :numtib)
+defVar(">IN", :toin)
+
+KEY = defPrim("KEY", (reg) -> begin
+ if toin >= numtib
end
+
+ return NEXT
+end)
+
+EMIT = defPrim("EMIT", (reg) -> begin
+
+ return NEXT
+end)
+
+WORD = defPrim("WORD", (reg) -> begin
+
+ return NEXT
+end)
+
+NUMBER = defPrim("NUMBER", (reg) -> begin
+
+ return NEXT
+end)
+
+#### VM loop ####
+function runVM(reg::Reg)
+ jmp = NEXT
+ while (jmp = callPrim(reg, jmp)) != 0 end
end
end
The Lambda Lab / projects / forth.jl.git / blobdiff