X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=src%2Fforth.jl;h=7cf0ca7d7d96d0c450c130758a318aab73f88618;hb=cccf599127228c9e6029deff1a6698a010089f50;hp=e720c7f375292e20e5c4fde896a99e291344956c;hpb=59bcf5a08895e8a9807701bfb63e89157a16c39b;p=forth.jl.git

diff --git a/src/forth.jl b/src/forth.jl
index e720c7f..7cf0ca7 100644
--- a/src/forth.jl
+++ b/src/forth.jl
@@ -1,23 +1,334 @@
-module FORTH
+module forth
 
-function input(prompt::AbstractString="")
-    print(prompt)
-    strip(readline)
+# VM mem size
+size_mem = 640*1024
+
+# Buffer sizes
+size_BIVar = 16 #
+size_RS = 1024   # Return stack size
+size_PS = 1024   # Parameter stack size
+size_TIB = 4096  # 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] = size_BIVar               # 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
+
+# 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 functions
+
+function pushRS(val::Int64)
+    mem[reg.RSP+=1] = val
 end
 
-dictCore = Set{AbstractString}([
-    "bye"
-])
+function popRS()
+    val = mem[reg.RSP]
+    reg.RSP -= 1
+    return val
+end
 
-function coreEval(word::AbstractString)
-    if word == "bye"
+function pushPS(val::Int64)
+    mem[reg.PSP += 1] = val
 end
 
-function repl()
+function popPS()
+    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
+
+callPrim(addr::Int64) = primitives[-addr]()
+
+function defExistingVar(name::AbstractString, varAddr::Int64; flags::Int64=0)
+    defPrim(name, eval(:(() -> begin
+        pushPS($(varAddr))
+        return NEXT
+    end)))
+end
+
+function defConst(name::AbstractString, val::Int64; flags::Int64=0)
+    defPrim(name, eval(:(() -> begin
+        pushPS($(val))
+        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
+
+# 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
+    mem[reg.PSP], mem[reg.PSP-1] = mem[reg.PSP-1], mem[reg.PSP]
+    return NEXT
+end)
+
+DUP = defPrim("DUP", () -> begin
+    pushPS(mem[reg.PSP])
+    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)
+defNewVar("STATE", 0)
+defNewVar("BASE", 10)
+
+# Constants
+
+defConst("VERSION", 1)
+defConst("DOCOL", DOCOL)
+
+# 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(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(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", TIB)
+
+#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
+
+# 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
 
-    while true
-        line = input()
+function dumpPS()
+    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