X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=src%2Fforth.jl;h=a115e48221200b5af56576cde1087f90ca66d325;hb=a4a274445e7ddaa07b595814dfeb9f6ddb0ce95a;hp=46c3c9c055935a0e2deb45b634c76b2a55e28e40;hpb=e7ffe0f277ef1d2b9b9005e01e2149b4d34190f7;p=forth.jl.git

diff --git a/src/forth.jl b/src/forth.jl
index 46c3c9c..a115e48 100644
--- a/src/forth.jl
+++ b/src/forth.jl
@@ -1,52 +1,479 @@
 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)
     
-    if ! (interpretPrimitive() ||
-        interpretNonPrimitive() ||
-        interpretNumber())
-        println("Error: unknown word '$word'.")
+    varAddr = mem[HERE] + 1
+    push!(primitives, eval(:(() -> begin
+        pushPS($(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
+
+# 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)
+
+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", 100)
+F_HIDEN = defConst("F_HIDDEN", 1000)
+
+# 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
+    
+    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'
+            break
+        end
+    end
+
+    wordLen = offset
+
+    pushPS(wordAddr)
+    pushPS(wordLen)
+
+    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
+
+# Debugging tools
+
+function coredump(startAddr::Int64; count::Int64 = 16, cellsPerLine::Int64 = 8)
+    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]<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 repl()
+function printPS()
+    count = reg.PSP - mem[PSP0]
 
-    mode = "interpret"
-    while mode != "stop"
-        modes[mode]()
+    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