module forth
# VM mem size
-size_mem = 640*1024
+size_mem = 1000000 # 1 mega-int
# Buffer sizes
-size_RS = 1024 # Return stack size
-size_PS = 1024 # Parameter stack size
-size_TIB = 1096 # Terminal input buffer size
+size_RS = 1000 # Return stack size
+size_PS = 1000 # Parameter stack size
+size_TIB = 1000 # Terminal input buffer size
# The mem array constitutes the memory of the VM. It has the following geography:
#
PSP::Int64 # Parameter/data stack pointer
IP::Int64 # Instruction pointer
W::Int64 # Working register
-
- source::Any # Input stream in use
end
-reg = Reg(mem[RSP0], mem[PSP0], 0, 0, STDIN)
+reg = Reg(mem[RSP0], mem[PSP0], 0, 0)
# Stack manipulation functions
-type StackUnderflow <: Exception end
+type ParamStackUnderflow <: Exception end
+type ReturnStackUnderflow <: Exception end
+
+Base.showerror(io::IO, ex::ParamStackUnderflow) = print(io, "Parameter stack underflow.")
+Base.showerror(io::IO, ex::ReturnStackUnderflow) = print(io, "Return stack underflow.")
getRSDepth() = reg.RSP - mem[RSP0]
getPSDepth() = reg.PSP - mem[PSP0]
function ensurePSDepth(depth::Int64)
if getPSDepth()<depth
- throw(StackUnderflow())
+ throw(ParamStackUnderflow())
end
end
function ensureRSDepth(depth::Int64)
if getRSDepth()<depth
- throw(StackUnderflow())
+ throw(ReturnStackUnderflow())
end
end
function defPrim(f::Function; name="nameless")
push!(primitives, f)
- push!(primNames, name)
+ push!(primNames, replace(replace(name, "\004", "EOF"), "\n", "\\n"))
return -length(primitives)
end
callPrim(addr::Int64) = primitives[-addr]()
-# Word creation
+# Word creation functions
function createHeader(name::AbstractString, flags::Int64)
mem[mem[HERE]] = mem[LATEST]
return addr
end
-# Variable creation
+# Variable creation functions
function defExistingVar(name::AbstractString, varAddr::Int64; flags::Int64=0)
codeWordAddr = mem[HERE]
varAddr = mem[HERE] + 1
- f = eval(:(() -> begin
- pushPS($(varAddr))
- return NEXT
- end))
-
- mem[mem[HERE]] = defPrim(f, name=name); mem[HERE] += 1
+ mem[mem[HERE]] = DOVAR; mem[HERE] += 1
mem[mem[HERE]] = initial; mem[HERE] += 1
return varAddr, codeWordAddr
end
function defConst(name::AbstractString, val::Int64; flags::Int64=0)
- defPrimWord(name, eval(:(() -> begin
- pushPS($(val))
- return NEXT
- end)))
+ createHeader(name, flags)
+
+ mem[mem[HERE]] = DOCON; mem[HERE] += 1
+ mem[mem[HERE]] = val; mem[HERE] += 1
return val
end
return NEXT
end, name="DOCOL")
+DOVAR = defPrim(() -> begin
+ pushPS(reg.W + 1)
+ return NEXT
+end, name="DOVAR")
+
+DOCON = defPrim(() -> begin
+ pushPS(mem[reg.W + 1])
+ return NEXT
+end, name="DOVAR")
+
EXIT = defPrimWord("EXIT", () -> begin
reg.IP = popRS()
return NEXT
end)
+# Dictionary entries for core built-in variables, constants
+
+HERE_CFA = defExistingVar("HERE", HERE)
+LATEST_CFA = defExistingVar("LATEST", LATEST)
+PSP0_CFA = defExistingVar("PSP0", PSP0)
+RSP0_CFA = defExistingVar("RSP0", RSP0)
+
+defConst("DOCOL", DOCOL)
+defConst("DOCON", DOCON)
+defConst("DOVAR", DOVAR)
+
+defConst("DICT", DICT)
+defConst("MEMSIZE", size_mem)
+
+F_IMMED = defConst("F_IMMED", 128)
+F_HIDDEN = defConst("F_HIDDEN", 256)
+F_LENMASK = defConst("F_LENMASK", 127)
+
# Basic forth primitives
DROP = defPrimWord("DROP", () -> begin
end)
DUP = defPrimWord("DUP", () -> begin
+ ensurePSDepth(1)
pushPS(mem[reg.PSP])
return NEXT
end)
a = popPS()
b = popPS()
c = popPS()
+ pushPS(b)
pushPS(a)
pushPS(c)
- pushPS(b)
return NEXT
end)
a = popPS()
b = popPS()
c = popPS()
- pushPS(b)
pushPS(a)
pushPS(c)
+ pushPS(b)
return NEXT
end)
+
TWODROP = defPrimWord("2DROP", () -> begin
popPS()
popPS()
d = popPS()
pushPS(b)
pushPS(a)
- pushPS(c)
pushPS(d)
+ pushPS(c)
+ return NEXT
+end)
+
+TWOOVER = defPrimWord("2OVER", () -> begin
+ ensurePSDepth(4)
+ a = mem[reg.PSP-3]
+ b = mem[reg.PSP-2]
+ pushPS(a)
+ pushPS(b)
return NEXT
end)
return NEXT
end)
+TWOMUL = defPrimWord("2*", () -> begin
+ pushPS(popPS() << 1)
+ return NEXT
+end)
+
+TWODIV = defPrimWord("2/", () -> begin
+ pushPS(popPS() >> 1)
+ return NEXT
+end)
+
EQU = defPrimWord("=", () -> begin
b = popPS()
a = popPS()
end)
-# Built-in variables
-
-HERE_CFA = defExistingVar("HERE", HERE)
-LATEST_CFA = defExistingVar("LATEST", LATEST)
-PSP0_CFA = defExistingVar("PSP0", PSP0)
-RSP0_CFA = defExistingVar("RSP0", RSP0)
-STATE, STATE_CFA = defNewVar("STATE", 0)
-BASE, BASE_CFA = 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 = defPrimWord(">R", () -> begin
return NEXT
end)
+RFETCH = defPrimWord("R@", () -> begin
+ pushPS(mem[reg.RSP])
+ return NEXT
+end)
+
RSPFETCH = defPrimWord("RSP@", () -> begin
pushPS(reg.RSP)
return NEXT
# I/O
+sources = Array{Any,1}()
+currentSource() = sources[length(sources)]
+
defConst("TIB", TIB)
NUMTIB, NUMTIB_CFA = defNewVar("#TIB", 0)
TOIN, TOIN_CFA = defNewVar(">IN", 0)
+EOF = defConst("EOF", 4)
KEY = defPrimWord("KEY", () -> begin
if mem[TOIN] >= mem[NUMTIB]
mem[TOIN] = 0
- if reg.source != STDIN && eof(reg.source)
- reg.source = STDIN
+ if !eof(currentSource())
+ line = readline(currentSource())
+ mem[NUMTIB] = length(line)
+ putString(line, TIB)
+ else
+ mem[NUMTIB] = 1
+ mem[TIB] = EOF
end
-
- line = readline(reg.source)
- mem[NUMTIB] = length(line)
- putString(line, TIB)
end
pushPS(mem[TIB + mem[TOIN]])
end)
WORD = defPrimWord("WORD", () -> begin
-
- c = -1
- skip_to_end = false
- while true
+ eof_char = Char(EOF)
+ c = eof_char
+ 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
wordAddr = mem[HERE]
offset = 0
- if c == '\n'
+ if c == '\n' || c == eof_char
# Treat newline as a special word
mem[wordAddr + offset] = Int64(c)
callPrim(mem[KEY])
c = Char(popPS())
- if c == ' ' || c == '\t' || c == '\n'
+ if c == ' ' || c == '\t' || c == '\n' || c == eof_char
# Rewind KEY
mem[TOIN] -= 1
break
return NEXT
end)
+BASE, BASE_CFA = defNewVar("BASE", 10)
NUMBER = defPrimWord("NUMBER", () -> begin
wordLen = popPS()
TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
+# Branching
+
+BRANCH = defPrimWord("BRANCH", () -> begin
+ reg.IP += mem[reg.IP]
+ return NEXT
+end)
+
+ZBRANCH = defPrimWord("0BRANCH", () -> begin
+ if (popPS() == 0)
+ reg.IP += mem[reg.IP]
+ else
+ reg.IP += 1
+ end
+
+ return NEXT
+end)
+
# Compilation
-CREATE = defPrimWord("CREATE", () -> begin
+STATE, STATE_CFA = defNewVar("STATE", 0)
+
+HEADER = defPrimWord("HEADER", () -> begin
wordLen = popPS()
wordAddr = popPS()
COLON = defWord(":",
[WORD,
- CREATE,
+ HEADER,
LIT, DOCOL, COMMA,
LATEST_CFA, FETCH, HIDDEN,
RBRAC,
return NEXT
end, flags=F_IMMED)
-TICK = defWord("'", [WORD, FIND, TOCFA, EXIT])
+TICK = defWord("'",
+ [WORD, FIND, TOCFA, EXIT])
-# Branching
+BTICK = defWord("[']",
+ [FROMR, DUP, INCR, TOR, FETCH, EXIT])
-BRANCH = defPrimWord("BRANCH", () -> begin
- reg.IP += mem[reg.IP]
- return NEXT
-end)
+# CREATE and DOES>
-ZBRANCH = defPrimWord("0BRANCH", () -> begin
- if (popPS() == 0)
- reg.IP += mem[reg.IP]
- else
- reg.IP += 1
- end
+CREATE = defWord("CREATE",
+ [WORD,
+ HEADER,
+ LIT, DOVAR, COMMA, EXIT]);
+DODOES = defPrim(() -> begin
+ pushRS(reg.IP)
+ reg.IP = reg.W + 1
return NEXT
-end)
+end, name="DOCOL")
+
+defConst("DODOES", DODOES)
+
+FROMDOES_PAREN = defWord("(DOES>)",
+ [DODOES, LATEST, FETCH, TOCFA, STORE, EXIT])
+
+FROMDOES = defWord("DOES>",
+ [BTICK, FROMDOES_PAREN, COMMA, BTICK, EXIT, COMMA,
+ BTICK, LIT, COMMA, LATEST, FETCH, TODFA, COMMA], flags=F_IMMED)
+
# Strings
return mem[reg.W]
end)
+type ParseError <: Exception
+ wordName::ASCIIString
+end
+Base.showerror(io::IO, ex::ParseError) = print(io, "Parse error at word: '$(ex.wordName)'.")
+
+DEBUG, DEBUG_CFA = defNewVar("DEBUG", 0)
+
INTERPRET = defPrimWord("INTERPRET", () -> begin
callPrim(mem[WORD])
wordName = getString(mem[reg.PSP-1], mem[reg.PSP])
- #println("... ", replace(wordName, "\n", "\\n"), " ...")
+ if mem[DEBUG] != 0
+ println("... ", replace(replace(wordName, "\004", "EOF"), "\n", "\\n"), " ...")
+ end
callPrim(mem[TWODUP])
callPrim(mem[FIND])
isImmediate = (mem[wordAddr+1] & F_IMMED) != 0
callPrim(mem[TOCFA])
- callPrim(mem[ROT]) # get rid of extra copy of word string details
+ callPrim(mem[NROT]) # get rid of extra copy of word string details
popPS()
popPS()
if mem[STATE] == 0 || isImmediate
# Execute!
- #println("Executing CFA at $(mem[reg.PSP])")
return callPrim(mem[EXECUTE])
else
# Append CFA to dictionary
callPrim(mem[NUMBER])
if popPS() != 0
- println("Parse error at word: '$wordName'")
- return NEXT
+ throw(ParseError(wordName))
end
if mem[STATE] == 0
return 0
end)
+PROMPT = defPrimWord("PROMPT", () -> begin
+ println(" ok")
+end)
+
NL = defPrimWord("\n", () -> begin
- if mem[STATE] == 0 && reg.source == STDIN
- println(" ok")
+ if mem[STATE] == 0 && currentSource() == STDIN
+ callPrim(mem[PROMPT])
end
return NEXT
end, flags=F_IMMED)
-# Odds and Ends
-
-CHAR = defPrimWord("CHAR", () -> begin
+INCLUDE = defPrimWord("INCLUDE", () -> begin
callPrim(mem[WORD])
wordLen = popPS()
wordAddr = popPS()
word = getString(wordAddr, wordLen)
- pushPS(Int64(word[1]))
+
+ push!(sources, open(word, "r"))
+
+ # Clear input buffer
+ mem[NUMTIB] = 0
return NEXT
end)
-INCLUDE = defPrimWord("INCLUDE", () -> begin
+EOF_WORD = defPrimWord("\x04", () -> begin
+ if currentSource() != STDIN
+ close(currentSource())
+ end
+
+ pop!(sources)
+
+ if length(sources)>0
+ if currentSource() == STDIN
+ callPrim(mem[PROMPT])
+ end
+
+ return NEXT
+ else
+ return 0
+ end
+end, flags=F_IMMED)
+# Odds and Ends
+
+CHAR = defPrimWord("CHAR", () -> begin
callPrim(mem[WORD])
wordLen = popPS()
wordAddr = popPS()
word = getString(wordAddr, wordLen)
-
- println("Reading from $word...")
-
- reg.source = open(word, "r")
-
- # Clear input buffer
- mem[NUMTIB] = 0
+ pushPS(Int64(word[1]))
return NEXT
end)
+initialized = false
+initFileName = nothing
+if isfile("lib.4th")
+ initFileName = "lib.4th"
+elseif isfile(Pkg.dir("forth/src/lib.4th"))
+ initFileName = Pkg.dir("forth/src/lib.4th")
+end
+
+
#### VM loop ####
-function run()
+function run(;initialize=true)
+ # Begin with STDIN as source
+ push!(sources, STDIN)
+
+ global initialized, initFileName
+ if !initialized && initialize
+ if initFileName != nothing
+ print("Including definitions from $initFileName...")
+ push!(sources, open(initFileName, "r"))
+ initialized = true
+ else
+ println("No library file found. Only primitive words available.")
+ end
+ end
+
# Start with IP pointing to first instruction of outer interpreter
reg.IP = QUIT + 1
# Primitive processing loop.
# Everyting else is simply a consequence of this loop!
jmp = NEXT
- while (jmp = callPrim(jmp)) != 0
- #println("Evaluating prim $jmp [$(primNames[-jmp])]")
+ while jmp != 0
+ try
+ if mem[DEBUG] != 0
+ println("Evaluating prim ", jmp," ", primNames[-jmp])
+ end
+
+ jmp = callPrim(jmp)
+
+ catch ex
+ showerror(STDOUT, ex)
+ println()
+
+ while !isempty(sources) && currentSource() != STDIN
+ close(pop!(sources))
+ end
+
+ mem[STATE] = 0
+ mem[NUMTIB] = 0
+ reg.PSP = mem[PSP0]
+ reg.RSP = mem[RSP0]
+ reg.IP = QUIT + 1
+ jmp = NEXT
+ end
end
end
end
end
+DUMP = defPrimWord("DUMP", () -> begin
+ count = popPS()
+ addr = popPS()
+
+ dump(addr, count=count)
+
+ return NEXT
+end)
+
end
The Lambda Lab / projects / forth.jl.git / blobdiff