module forth
-RS = Array{Int64, 1}()
-DS = Array{Int64, 1}()
+# VM mem size
+size_mem = 640*1024
-primitives = Array{Expr,1}()
-memory = Array{Int,1}()
-headers = Array{Tuple{AbstractString, Int},1}
+# Buffer sizes
+size_RS = 1024 # Return stack size
+size_PS = 1024 # Parameter stack size
+size_TIB = 1096 # Terminal input buffer size
-function addPrim(name::AbstractString, expr::Expr)
- push!(primitives, expr)
- push!(memory, -length(primitives))
- push!(headers, length(memory))
+# 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 ensureRSDepth(depth::Int64)
+ if getRSDepth()<depth
+ throw(StackUnderflow())
+ end
+end
+
+function pushRS(val::Int64)
+ mem[reg.RSP+=1] = val
+end
+
+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
+
+# Handy functions for adding/retrieving strings to/from memory.
+
+getString(addr::Int64, len::Int64) = ASCIIString([Char(c) for c in mem[addr:(addr+len-1)]])
+function putString(str::ASCIIString, addr::Int64)
+ mem[addr:(addr+length(str)-1)] = [Int64(c) for c in str]
+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
+ putString(name, mem[HERE]); mem[HERE] += length(name)
+end
+
+function defPrim(name::AbstractString, f::Function; flags::Int64=0)
+ createHeader(name, flags)
+
+ codeWordAddr = mem[HERE]
+ push!(primitives, f)
+ mem[codeWordAddr] = -length(primitives)
+ mem[HERE] += 1
+
+ return codeWordAddr
+end
+
+callPrim(addr::Int64) = primitives[-addr]()
+
+function defExistingVar(name::AbstractString, varAddr::Int64; flags::Int64=0)
+ defPrim(name, eval(:(() -> begin
+ pushPS($(varAddr))
+ return mem[NEXT]
+ end)))
+end
+
+function defNewVar(name::AbstractString, initial::Int64; flags::Int64=0)
+ createHeader(name, flags)
+
+ varAddr = mem[HERE] + 1
+ push!(primitives, eval(:(() -> begin
+ pushPS($(varAddr))
+ return mem[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 mem[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]] = mem[DOCOL]
+ mem[HERE] += 1
+
+ for wordAddr in wordAddrs
+ mem[mem[HERE]] = wordAddr
+ mem[HERE] += 1
+ end
+
+ return addr
+end
+
+# Threading Primitives (inner interpreter)
+
+NEXT = defPrim("NEXT", () -> begin
+ reg.W = mem[reg.IP]
+ reg.IP += 1
+ return mem[reg.W]
+end)
+
+DOCOL = defPrim("DOCOL", () -> begin
+ pushRS(reg.IP)
+ reg.IP = reg.W + 1
+ return mem[NEXT]
+end)
+
+EXIT = defPrim("EXIT", () -> begin
+ reg.IP = popRS()
+ return mem[NEXT]
+end)
+
+# Basic forth primitives
+
+DROP = defPrim("DROP", () -> begin
+ popPS()
+ return mem[NEXT]
+end)
+
+SWAP = defPrim("SWAP", () -> begin
+ a = popPS()
+ b = popPS()
+ pushPS(a)
+ pushPS(b)
+ return mem[NEXT]
+end)
+
+DUP = defPrim("DUP", () -> begin
+ pushPS(mem[reg.PSP])
+ return mem[NEXT]
+end)
+
+OVER = defPrim("OVER", () -> begin
+ ensurePSDepth(2)
+ pushPS(mem[reg.PSP-1])
+ return mem[NEXT]
+end)
+
+ROT = defPrim("ROT", () -> begin
+ a = popPS()
+ b = popPS()
+ c = popPS()
+ pushPS(a)
+ pushPS(c)
+ pushPS(b)
+ return mem[NEXT]
+end)
+
+NROT = defPrim("-ROT", () -> begin
+ a = popPS()
+ b = popPS()
+ c = popPS()
+ pushPS(b)
+ pushPS(a)
+ pushPS(c)
+ return mem[NEXT]
+end)
+
+TWODROP = defPrim("2DROP", () -> begin
+ popPS()
+ popPS()
+ return mem[NEXT]
+end)
+
+TWODUP = defPrim("2DUP", () -> begin
+ ensurePSDepth(2)
+ a = mem[reg.PSP-1]
+ b = mem[reg.PSP]
+ pushPS(a)
+ pushPS(b)
+ return mem[NEXT]
+end)
+
+TWOSWAP = defPrim("2SWAP", () -> begin
+ a = popPS()
+ b = popPS()
+ c = popPS()
+ d = popPS()
+ pushPS(b)
+ pushPS(a)
+ pushPS(c)
+ pushPS(d)
+ return mem[NEXT]
+end)
+
+QDUP = defPrim("?DUP", () -> begin
+ ensurePSDepth(1)
+ val = mem[reg.PSP]
+ if val != 0
+ pushPS(val)
+ end
+ return mem[NEXT]
+end)
+
+INCR = defPrim("1+", () -> begin
+ ensurePSDepth(1)
+ mem[reg.PSP] += 1
+ return mem[NEXT]
+end)
+
+DECR = defPrim("1-", () -> begin
+ ensurePSDepth(1)
+ mem[reg.PSP] -= 1
+ return mem[NEXT]
+end)
+
+INCR2 = defPrim("2+", () -> begin
+ ensurePSDepth(1)
+ mem[reg.PSP] += 2
+ return mem[NEXT]
+end)
+
+DECR2 = defPrim("2-", () -> begin
+ ensurePSDepth(1)
+ mem[reg.PSP] -= 2
+ return mem[NEXT]
+end)
+
+ADD = defPrim("+", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a+b)
+ return mem[NEXT]
+end)
+
+SUB = defPrim("-", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a-b)
+ return mem[NEXT]
+end)
+
+MUL = defPrim("*", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a*b)
+ return mem[NEXT]
+end)
+
+DIVMOD = defPrim("/MOD", () -> begin
+ b = popPS()
+ a = popPS()
+ q,r = divrem(a,b)
+ pushPS(r)
+ pushPS(q)
+ return mem[NEXT]
+end)
+
+EQU = defPrim("=", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a==b ? -1 : 0)
+ return mem[NEXT]
+end)
+
+NEQU = defPrim("<>", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a!=b ? -1 : 0)
+ return mem[NEXT]
+end)
+
+LT = defPrim("<", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a<b ? -1 : 0)
+ return mem[NEXT]
+end)
+
+GT = defPrim(">", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a>b ? -1 : 0)
+ return mem[NEXT]
+end)
+
+LE = defPrim("<=", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a<=b ? -1 : 0)
+ return mem[NEXT]
+end)
+
+GE = defPrim(">=", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a>=b ? -1 : 0)
+ return mem[NEXT]
+end)
+
+ZEQU = defPrim("0=", () -> begin
+ pushPS(popPS() == 0 ? -1 : 0)
+ return mem[NEXT]
+end)
+
+ZNEQU = defPrim("0<>", () -> begin
+ pushPS(popPS() != 0 ? -1 : 0)
+ return mem[NEXT]
+end)
+
+ZLT = defPrim("0<", () -> begin
+ pushPS(popPS() < 0 ? -1 : 0)
+ return mem[NEXT]
+end)
+
+ZGT = defPrim("0>", () -> begin
+ pushPS(popPS() > 0 ? -1 : 0)
+ return mem[NEXT]
+end)
+
+ZLE = defPrim("0<=", () -> begin
+ pushPS(popPS() <= 0 ? -1 : 0)
+ return mem[NEXT]
+end)
+
+ZGE = defPrim("0>=", () -> begin
+ pushPS(popPS() >= 0 ? -1 : 0)
+ return mem[NEXT]
+end)
+
+AND = defPrim("AND", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a & b)
+ return mem[NEXT]
+end)
+
+OR = defPrim("OR", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a | b)
+ return mem[NEXT]
+end)
+
+XOR = defPrim("XOR", () -> begin
+ b = popPS()
+ a = popPS()
+ pushPS(a $ b)
+ return mem[NEXT]
+end)
+
+INVERT = defPrim("INVERT", () -> begin
+ pushPS(~popPS())
+ return mem[NEXT]
+end)
+
+# Literals
+
+LIT = defPrim("LIT", () -> begin
+ pushPS(mem[reg.IP])
+ reg.IP += 1
+ return mem[NEXT]
+end)
+
+# Memory primitives
+
+STORE = defPrim("!", () -> begin
+ addr = popPS()
+ dat = popPS()
+ mem[addr] = dat
+ return mem[NEXT]
+end)
+
+FETCH = defPrim("@", () -> begin
+ addr = popPS()
+ pushPS(mem[addr])
+ return mem[NEXT]
+end)
+
+ADDSTORE = defPrim("+!", () -> begin
+ addr = popPS()
+ toAdd = popPS()
+ mem[addr] += toAdd
+ return mem[NEXT]
+end)
+
+SUBSTORE = defPrim("-!", () -> begin
+ addr = popPS()
+ toSub = popPS()
+ mem[addr] -= toSub
+ return mem[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 mem[NEXT]
+end)
+
+FROMR = defPrim("R>", () -> begin
+ pushPS(popRS())
+ return mem[NEXT]
+end)
+
+RSPFETCH = defPrim("RSP@", () -> begin
+ pushPS(reg.RSP)
+ return mem[NEXT]
+end)
+
+RSPSTORE = defPrim("RSP!", () -> begin
+ RSP = popPS()
+ return mem[NEXT]
+end)
+
+RDROP = defPrim("RDROP", () -> begin
+ popRS()
+ return mem[NEXT]
+end)
+
+# Parameter Stack
+
+PSPFETCH = defPrim("PSP@", () -> begin
+ pushPS(reg.PSP)
+ return mem[NEXT]
+end)
+
+PSPSTORE = defPrim("PSP!", () -> begin
+ PSP = popPS()
+ return mem[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)
+ putString(line, TIB)
+ end
+
+ pushPS(mem[TIB + mem[TOIN]])
+ mem[TOIN] += 1
+
+ return mem[NEXT]
+end)
+
+EMIT = defPrim("EMIT", () -> begin
+ print(Char(popPS()))
+ return mem[NEXT]
+end)
+
+WORD = defPrim("WORD", () -> begin
+
+ c = -1
+
+ skip_to_end = false
+ while true
+
+ callPrim(mem[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(mem[KEY])
+ c = Char(popPS())
+
+ if c == ' ' || c == '\t' || c == '\n'
+ break
+ end
+ end
+
+ wordLen = offset
+
+ pushPS(wordAddr)
+ pushPS(wordLen)
+
+ return mem[NEXT]
+end)
+
+NUMBER = defPrim("NUMBER", () -> begin
+
+ wordLen = popPS()
+ wordAddr = popPS()
+
+ s = getString(wordAddr, wordLen)
+
+ try
+ pushPS(parse(Int64, s, mem[BASE]))
+ pushPS(0)
+ catch
+ pushPS(1) # Error indication
+ end
+
+ return mem[NEXT]
+end)
+
+# Dictionary searches
+
+FIND = defPrim("FIND", () -> begin
+
+ wordLen = popPS()
+ wordAddr = popPS()
+ word = getString(wordAddr, wordLen)
+
+ latest = LATEST
+
+ i = 0
+ while (latest = mem[latest]) > 0
+ lenAndFlags = mem[latest+1]
+ len = lenAndFlags & F_LENMASK
+ hidden = (lenAndFlags & F_HIDDEN) == F_HIDDEN
+
+ if hidden || len != wordLen
+ continue
+ end
+
+ thisAddr = latest+2
+ thisWord = getString(thisAddr, len)
+
+ if thisWord == word
+ break
+ end
+ end
+
+ pushPS(latest)
+
+ return mem[NEXT]
+end)
+
+TOCFA = defPrim(">CFA", () -> begin
+
+ addr = popPS()
+ lenAndFlags = mem[addr+1]
+ len = lenAndFlags & F_LENMASK
+
+ pushPS(addr + 2 + len)
+
+ return mem[NEXT]
+end)
+
+TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
+
+# Compilation
+
+CREATE = defPrim("CREATE", () -> begin
+
+ wordLen = popPS()
+ wordAddr = popPS()
+ word = getString(wordAddr, wordLen)
+
+ createHeader(word, 0)
+
+ return mem[NEXT]
+end)
+
+COMMA = defPrim(",", () -> begin
+ mem[mem[HERE]] = popPS()
+ mem[HERE] += 1
+
+ return mem[NEXT]
+end)
+
+LBRAC = defPrim("[", () -> begin
+ mem[STATE] = 0
+ return mem[NEXT]
+end, flags=F_IMMED)
+
+RBRAC = defPrim("]", () -> begin
+ mem[STATE] = 1
+ return mem[NEXT]
+end, flags=F_IMMED)
+
+HIDDEN = defPrim("HIDDEN", () -> begin
+ addr = popPS() + 1
+ mem[addr] = mem[addr] $ F_HIDDEN
+ return mem[NEXT]
+end)
+
+HIDE = defWord("HIDE",
+ [WORD,
+ FIND,
+ HIDDEN,
+ EXIT])
+
+COLON = defWord(":",
+ [WORD,
+ CREATE,
+ LIT, DOCOL, COMMA,
+ LATEST, FETCH, HIDDEN,
+ RBRAC,
+ EXIT])
+
+SEMICOLON = defWord(";",
+ [LIT, EXIT, COMMA,
+ LATEST, FETCH, HIDDEN,
+ LBRAC,
+ EXIT], flags=F_IMMED)
+
+IMMEDIATE = defPrim("IMMEDIATE", () -> begin
+ lenAndFlagsAddr = mem[LATEST] + 1
+ mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
+ return mem[NEXT]
+end, flags=F_IMMED)
+
+TICK = defWord("'", [WORD, FIND, TOCFA, EXIT])
+
+# Branching
+
+BRANCH = defPrim("BRANCH", () -> begin
+ reg.IP += mem[reg.IP]
+ return mem[NEXT]
+end)
+
+ZBRANCH = defPrim("0BRANCH", () -> begin
+ if (popPS() == 0)
+ reg.IP += mem[reg.IP]
+ else
+ reg.IP += 1
+ end
+
+ return mem[NEXT]
+end)
+
+# Strings
+
+LITSTRING = defPrim("LITSTRING", () -> begin
+ len = mem[reg.IP]
+ reg.IP += 1
+ pushPS(reg.IP)
+ pushPS(len)
+ reg.IP += len
+
+ return mem[NEXT]
+end)
+
+#### VM loop ####
+function runVM()
+ jmp = mem[NEXT]
+ while (jmp = callPrim(jmp)) != 0 end
end
-addPrim("docol", :(begin
+# Debugging tools
-end))
+function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
+ chars = Array{Char,1}(cellsPerLine)
+
+ 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]<128)
+ 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(" $(mem[i])")
+ end
+ println()
+ else
+ println("Parameter stack empty")
+ end
+end
+
+function printRS()
+ count = reg.RSP - mem[RSP0]
+
+ if count > 0
+ print("<$count>")
+ for i in (mem[RSP0]+1):reg.RSP
+ print(" $(mem[i])")
+ end
+ println()
+ else
+ println("Return stack empty")
+ end
+end
end
The Lambda Lab / projects / forth.jl.git / blobdiff