module forth
-currentLine = ""
-currentPos = 0
+# VM mem size
+size_mem = 640*1024
-function nextLine()
- if eof(STDIN)
- return false
- else
- currentLine = readLine()
- currentPos = 1
- return true
+# Buffer sizes
+size_RS = 1024 # Return stack size
+size_PS = 1024 # Parameter stack size
+size_TIB = 1096 # Terminal input buffer size
+
+# The mem array constitutes the memory of the VM. It has the following geography:
+#
+# mem = +-----------------------+
+# | 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.
+#
+# 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.
+
+mem = Array{Int64,1}(size_mem)
+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
+
+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
+
+DICT = mem[HERE] # Save bottom of dictionary as constant
+
+# 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
+reg = Reg(mem[RSP0], mem[PSP0], 0, 0, 0)
+
+# Stack manipulation
+
+type StackUnderflow <: Exception end
+
+getRSDepth() = reg.RSP - mem[RSP0]
+getPSDepth() = reg.PSP - mem[PSP0]
+
+function ensurePSDepth(depth::Int64)
+ if getPSDepth()<depth
+ throw(StackUnderflow())
end
end
-function readPattern(pattern::Regex)
- m = match(pattern, currentLine)
- pos += length(m.match)
- return m.match
+function ensureRSDepth(depth::Int64)
+ if getRSDepth()<depth
+ throw(StackUnderflow())
+ end
end
-modes = Dict{AbstractString,Function}()
-mode = ""
+function pushRS(val::Int64)
+ mem[reg.RSP+=1] = val
+end
-function interpretPrimitive()
- if haskey(dict, word)
- dict[word]()
- return true
- else
- return false
+function popRS()
+ ensureRSDepth(1)
+
+ val = mem[reg.RSP]
+ reg.RSP -= 1
+ return val
+end
+
+function pushPS(val::Int64)
+ mem[reg.PSP += 1] = val
+end
+
+function popPS()
+ ensurePSDepth(1)
+
+ val = mem[reg.PSP]
+ reg.PSP -= 1
+ return val
+end
+
+# Primitive creation and calling functions
+
+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)
+end
+
+function defPrim(name::AbstractString, f::Function; flags::Int64=0)
+ createHeader(name, flags)
+
+ push!(primitives, f)
+ mem[mem[HERE]] = -length(primitives)
+ mem[HERE] += 1
+
+ return -length(primitives)
end
-interpretNonPrimitive() = false
-interpretNumber() = false
-modes["interpret"] = () -> begin
- getWord()
+callPrim(addr::Int64) = primitives[-addr]()
+
+function defExistingVar(name::AbstractString, varAddr::Int64; flags::Int64=0)
+ defPrim(name, eval(:(() -> begin
+ pushPS($(varAddr))
+ return NEXT
+ end)))
+end
+
+function defNewVar(name::AbstractString, initial::Int64; flags::Int64=0)
+ createHeader(name, flags)
+
+ varAddr = mem[HERE] + 1
+ push!(primitives, eval(:(() -> begin
+ pushPS($(varAddr))
+ return NEXT
+ end)))
+ mem[mem[HERE]] = -length(primitives); mem[HERE] += 1
+
+ mem[mem[HERE]] = initial; mem[HERE] += 1
+
+ return varAddr
+end
+
+function defConst(name::AbstractString, val::Int64; flags::Int64=0)
+ defPrim(name, eval(:(() -> begin
+ pushPS($(val))
+ return 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]] = DOCOL
+ mem[HERE] += 1
+
+ for wordAddr in wordAddrs
+ mem[mem[HERE]] = wordAddr
+ mem[HERE] += 1
+ end
+
+ return addr
+end
+
+# Threading Primitives
+
+NEXT = defPrim("NEXT", () -> begin
+ reg.W = mem[reg.IP]
+ reg.IP += 1
+ X = mem[reg.W]
+ return X
+end)
+
+DOCOL = defPrim("DOCOL", () -> begin
+ pushRS(reg.IP)
+ reg.IP = reg.W + 1
+ return NEXT
+end)
+
+EXIT = defPrim("EXIT", () -> begin
+ reg.IP = popRS()
+ return NEXT
+end)
+
+
+# Basic forth primitives
+
+DROP = defPrim("DROP", () -> begin
+ popPS()
+ return NEXT
+end)
+
+SWAP = defPrim("SWAP", () -> begin
+ a = popPS()
+ b = popPS()
+ pushPS(a)
+ pushPS(b)
+ return NEXT
+end)
+
+DUP = defPrim("DUP", () -> begin
+ pushPS(mem[reg.PSP])
+ return NEXT
+end)
+
+OVER = defPrim("OVER", () -> begin
+ ensurePSDepth(2)
+ pushPS(mem[reg.PSP-1])
+ return NEXT
+end)
+
+ROT = defPrim("ROT", () -> begin
+ a = popPS()
+ b = popPS()
+ c = popPS()
+ pushPS(a)
+ pushPS(c)
+ pushPS(b)
+ return NEXT
+end)
+
+NROT = defPrim("-ROT", () -> begin
+ a = popPS()
+ b = popPS()
+ c = popPS()
+ pushPS(b)
+ pushPS(a)
+ pushPS(c)
+ return NEXT
+end)
+
+TWODROP = defPrim("2DROP", () -> begin
+ popPS()
+ popPS()
+ return NEXT
+end)
+
+TWODUP = defPrim("2DUP", () -> begin
+ ensurePSDepth(2)
+ a = mem[reg.PSP-1]
+ b = mem[reg.PSP]
+ pushPS(a)
+ pushPS(b)
+ return NEXT
+end)
+
+TWOSWAP = defPrim("2SWAP", () -> begin
+ a = popPS()
+ b = popPS()
+ c = popPS()
+ d = popPS()
+ pushPS(b)
+ pushPS(a)
+ pushPS(c)
+ pushPS(d)
+ return NEXT
+end)
+
+QDUP = defPrim("?DUP", () -> begin
+ ensurePSDepth(1)
+ val = mem[reg.PSP]
+ if val != 0
+ pushPS(val)
+ end
+ return NEXT
+end)
+
+INCR = defPrim("1+", () -> begin
+ ensurePSDepth(1)
+ mem[reg.PSP] += 1
+ return NEXT
+end)
+
+DECR = defPrim("1-", () -> begin
+ ensurePSDepth(1)
+ mem[reg.PSP] -= 1
+ return NEXT
+end)
+
+ADD = defPrim("+", () -> begin
+ a = popPS()
+ b = popPS()
+ pushPS(a+b)
+ return NEXT
+end)
+
+SUB = defPrim("-", () -> begin
+ a = popPS()
+ b = popPS()
+ pushPS(b-a)
+ return NEXT
+end)
+
+MUL = defPrim("*", () -> begin
+ a = popPS()
+ b = popPS()
+ pushPS(a*b)
+ return NEXT
+end)
+
+DIVMOD = defPrim("/MOD", () -> begin
+ a = popPS()
+ b = popPS()
+ q,r = divrem(b,a)
+ pushPS(r)
+ pushPS(q)
+ return NEXT
+end)
+
+LIT = defPrim("LIT", () -> begin
+ pushPS(mem[reg.IP])
+ reg.IP += 1
+ return NEXT
+end)
+
+# Memory primitives
+
+STORE = defPrim("!", () -> begin
+ addr = popPS()
+ dat = popPS()
+ mem[addr] = dat
+ return NEXT
+end)
+
+FETCH = defPrim("@", () -> begin
+ addr = popPS()
+ pushPS(mem[addr])
+ return NEXT
+end)
+
+ADDSTORE = defPrim("+!", () -> begin
+ addr = popPS()
+ toAdd = popPS()
+ mem[addr] += toAdd
+ return NEXT
+end)
+
+SUBSTORE = defPrim("-!", () -> begin
+ addr = popPS()
+ toSub = popPS()
+ mem[addr] -= toSub
+ 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
+ pushRS(popPS())
+ return NEXT
+end)
+
+FROMR = defPrim("R>", () -> begin
+ pushPS(popRS())
+ return NEXT
+end)
+
+RSPFETCH = defPrim("RSP@", () -> begin
+ pushPS(reg.RSP)
+ return NEXT
+end)
+
+RSPSTORE = defPrim("RSP!", () -> begin
+ RSP = popPS()
+ return NEXT
+end)
+
+RDROP = defPrim("RDROP", () -> begin
+ popRS()
+ return NEXT
+end)
+
+# Parameter Stack
+
+PSPFETCH = defPrim("PSP@", () -> begin
+ pushPS(reg.PSP)
+ return NEXT
+end)
+
+PSPSTORE = defPrim("PSP!", () -> begin
+ 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
+
+ return NEXT
+end)
+
+EMIT = defPrim("EMIT", () -> begin
+ print(Char(popPS()))
+ return NEXT
+end)
+
+WORD = defPrim("WORD", () -> begin
- if ! (interpretPrimitive() ||
- interpretNonPrimitive() ||
- interpretNumber())
- println("Error: unknown word '$word'.")
+ c = -1
+
+ skip_to_end = false
+ while true
+
+ callPrim(KEY)
+ c = Char(popPS())
+
+ if c == '\\'
+ skip_to_end = true
+ continue
+ end
+
+ if skip_to_end
+ if c == '\n'
+ skip_to_end = false
+ end
+ continue
+ end
+
+ if c == ' ' || c == '\t'
+ continue
+ end
+
+ break
end
+
+ wordAddr = mem[HERE]
+ offset = 0
+
+ while true
+ mem[wordAddr + offset] = Int64(c)
+ offset += 1
+
+ callPrim(KEY)
+ c = Char(popPS())
+
+ if c == ' ' || c == '\t' || c == '\n'
+ break
+ end
+ end
+
+ wordLen = offset
+
+ pushPS(wordAddr)
+ pushPS(wordLen)
+
+ return NEXT
+end)
+
+NUMBER = defPrim("NUMBER", () -> begin
+
+ wordLen = popPS()
+ wordAddr = popPS()
+
+ s = ASCIIString([Char(c) for c in mem[wordAddr:(wordAddr+wordLen-1)]])
+
+ try
+ pushPS(parse(Int64, s, mem[BASE]))
+ pushPS(0)
+ catch
+ pushPS(1) # Error indication
+ end
+
+ return NEXT
+end)
+
+# Dictionary searches
+
+FIND = defPrim("FIND", () -> begin
+
+ wordLen = popPS()
+ wordAddr = popPS()
+ word = ASCIIString([Char(c) for c in mem[wordAddr:(wordAddr+wordLen-1)]])
+
+ latest = mem[LATEST]
+
+ while 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)]])
+
+ if thisWord == word
+ break
+ end
+ end
+
+ pushPS(latest)
+
+ return NEXT
+end)
+
+TOCFA = defPrim(">CFA", () -> begin
+
+ addr = popPS()
+ lenAndFlags = mem[addr+1]
+ len = lenAndFlags & F_LENMASK
+
+ pushPS(addr + 2 + len)
+
+ return NEXT
+end)
+
+TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
+
+#### VM loop ####
+function runVM()
+ jmp = NEXT
+ while (jmp = callPrim(jmp)) != 0 end
end
-function repl()
+# Debugging tools
+
+function coredump(startAddr::Int64; count::Int64 = 16, cellsPerLine::Int64 = 8)
+ chars = Array{Char,1}(cellsPerLine)
- mode = "interpret"
- while mode != "stop"
- modes[mode]()
+ for i in 0:(count-1)
+ addr = startAddr + i
+ if i%cellsPerLine == 0
+ print("$addr:")
+ end
+
+ print("\t$(mem[addr]) ")
+
+ if (mem[addr]>=32 && mem[addr]<176)
+ chars[i%cellsPerLine + 1] = Char(mem[addr])
+ else
+ chars[i%cellsPerLine + 1] = '.'
+ end
+
+ if i%cellsPerLine == cellsPerLine-1
+ println(string("\t", ASCIIString(chars)))
+ end
+ end
+end
+
+function printPS()
+ count = reg.PSP - mem[PSP0]
+
+ if count > 0
+ print("<$count>")
+ for i in (mem[PSP0]+1):reg.PSP
+ print(" $(mem[i])")
+ end
+ println()
+ else
+ println("Parameter stack empty")
end
end
The Lambda Lab / projects / forth.jl.git / blobdiff