M2000 Compiler Task

From Rosetta Code

One module compile, including lexical analyzer, syntax analyzer, code generator and virtual machine interpreter. The VM running using lambda functions, which include in an inventory (a kind of map), so each byte code is a key to this inventory, and the vm loop is just three lines. Normally functions (including lambda functions) and modules have own name space, but we can call functions with a L Call Local statement, which place the same name space of the caller (subroutines get always name space from the caller). Each module get a string (the (a$) is a syntactic sugar, interpreter insert a Read a$ when module added to modules/function list), and place a string to the stack of values. So we have to put one module after the other to do all the process.

The stack of values internal is a collection, which we can add to top (using Push) or to bottom (using Data) and we can pop values using Read, or peak values using ItemStack() and ItemStack$() for strings. A module get the parent stack of value, a function in an expression has own stack of value. We can switch temporary to a new stack using a Stack New { } statement, and at the end of this the previous object attach to "process object". (modules and functions run on separate process objects, subs are implemented in execution code, they are not objects).

Enum variables can return the name of value using a Eval$(enum_name_or_variable), So we can store values as Enum types, and handle them as numbers and as strings (using Eval$()). Functions Eval() and Eval$() do many things, depends of the first argument.

Generator save the byte code to a byte buffer. In a buffer bytes, integer, long are unsigned numbers. We have to use Uint(a) to place a signed value, and Sint() to get the signed from buffer. Also we can read from bytes offsets using casting to integer or to long, which we done here to get the long value after the operand (like in jmp or in fetch).

lambda functions can get closures as copies. In lexical analyzer the Scanner variable is a pointer to a buffer, so the copy is a reference. Lambda functions are not reference type, but a value type. We can pass a lambda as a closure too.

Select Case is a mystery in M2000. We can have one line after Case or a Block but no blank lines. This happen because interpreter execute code every time from source; Only look ahead to find if an expression is a string or number which is very fast because, strings functions and variables have $ at the end of name. Maybe some day interpreter find a lexical/syntax analyzer, but for this time works as one function which consume source code.

Image

M2000 Interpreter[edit]

 
Module CompilerExample {
Set Fast !
Module lexical_analyzer (a$){
lim=Len(a$)
LineNo=1
ColumnNo=1
Document Output$
Buffer Scanner as Integer*lim
Return Scanner, 0:=a$
offset=0
buffer1$=""
flag_rem=true
Ahead=lambda Scanner (a$, offset)->{
=false
Try {
\\ second parameter is the offset in buffer units
\\ third parameter is length in bytes
=Eval$(Scanner, offset,2*len(a$))=a$
}
}
Ahead2=lambda Scanner (a$, offset)->{
=false
Try {
=Eval$(Scanner, offset,2) ~ a$
}
}
const nl$=chr$(13)+chr$(10), quo$="""", er$="@", Ansi=3
Try {
Do
If Ahead("/*", offset) Then {
offset+=2 : ColumnNo+=2
While not Ahead("*/", offset)
If Ahead(nl$, offset) Then
lineNo++: ColumnNo=1 : offset+=2
Else
offset++ : ColumnNo++
End If
if offset>lim then
Error "End-of-file in comment. Closing comment characters not found"+er$
End if
End While
offset+=2 : ColumnNo+=2
} Else.if Ahead(nl$, offset) Then{
LineNo++: ColumnNo=1
offset+=2
} Else.if Ahead(quo$, offset) Then {
Output$=format$("{0::-10}{1::-10} ", LineNo, ColumnNo)
offset++ : ColumnNo++
strin=offset
While not Ahead(quo$, offset)
If Ahead("/", offset) Then
offset+=2 : ColumnNo+=2
else
offset++ : ColumnNo++
End if
checkerror()
End While
Output$="String "+quote$(Eval$(Scanner, strin, (offset-strin)*2))+nl$
offset++ : ColumnNo++
} Else.if Ahead("'", offset) Then {
Output$=format$("{0::-10}{1::-10} ", LineNo, ColumnNo)
offset++ : ColumnNo++
strin=offset
While not Ahead("'", offset)
If Ahead("/", offset) Then
offset+=2 : ColumnNo+=2
else
offset++ : ColumnNo++
End if
checkerror()
End While
lit$=format$(Eval$(Scanner, strin, (offset-strin)*2))
select case len(lit$)
case 1
Output$="Integer "+str$(asc(lit$),0)+nl$
case >1
{Error "Multi-character constant."+er$}
case 0
{Error "Empty character constant."+er$}
end select
offset++ : ColumnNo++
} Else.if Ahead2("[a-z]", offset) Then {
strin=offset
Output$=format$("{0::-10}{1::-10} ", LineNo, ColumnNo)
offset++ : ColumnNo++
While Ahead2("[a-zA-Z0-9_]", offset)
offset++ : ColumnNo++
End While
Keywords(Eval$(Scanner, strin, (offset-strin)*2))
} Else.if Ahead2("[0-9]", offset) Then {
strin=offset
Output$=format$("{0::-10}{1::-10} Integer ", LineNo, ColumnNo)
offset++ : ColumnNo++
While Ahead2("[0-9]", offset)
offset++ : ColumnNo++
End While
if Ahead2("[a-zA-Z_]", offset) then
{Error " Invalid number. Starts like a number, but ends in non-numeric characters."+er$}
else
Output$=Eval$(Scanner, strin, (offset-strin)*2)+nl$
end if
} Else {
Symbols(Eval$(Scanner, Offset, 2))
offset++ : ColumnNo++
}
Until offset>=lim
}
er1$=leftpart$(error$,er$)
if er1$<>"" then
Print
Report "Error:"+er1$
Output$="(Error)"+nl$+"Error:"+er1$
else
Output$=format$("{0::-10}{1::-10}", LineNo, ColumnNo)+" End_of_Input"+nl$
end if
Push Output$
Exit
Clipboard Output$
Save.Doc Output$, "lex.t", Ansi
document lex$
Load.Doc lex$,"lex.t", Ansi
Report lex$
 
Sub Keywords(a$)
select case a$
case "if"
a$="Keyword_if"
case "else"
a$="Keyword_else"
case "while"
a$="Keyword_while"
case "print"
a$="Keyword_print"
case "putc"
a$="Keyword_putc"
else case
a$="Identifier "+a$
end select
Output$=a$+nl$
End sub
Sub Symbols(a$)
select case a$
case " ", chr$(9)
a$=""
case "("
a$="LeftParen"
case ")"
a$="RightParen"
case "{"
a$="LeftBrace"
case "}"
a$="RightBrace"
case ";"
a$="Semicolon"
case ","
a$="Comma"
case "*"
a$="Op_multiply"
case "/"
a$="Op_divide"
case "+"
a$="Op_add"
case "-"
a$="Op_subtract"
case "%"
a$="Op_mod"
case "<"
{ if Ahead("=", offset+1) Then
offset++
a$="Op_lessequal"
ColumnNo++
else
a$="Op_less"
end if
}
case ">"
{ if Ahead("=", offset+1) Then
offset++
ColumnNo++
a$="Op_greaterequal"
else
a$="Op_greater"
end if
}
case "="
{ if Ahead("=", offset+1) Then
offset++
ColumnNo++
a$="Op_equal"
else
a$="Op_assign"
end if
}
case "!"
{ if Ahead("=", offset+1) Then
offset++
ColumnNo++
a$="Op_notequal"
else
a$="Op_not"
end if
}
case "&"
{ if Ahead("&", offset+1) Then
offset++
ColumnNo++
a$="Op_and"
else
a$=""
end if
}
case "|"
{ if Ahead("|", offset+1) Then
offset++
ColumnNo++
a$="Op_or"
else
a$=""
end if
}
else case
{Error "Unrecognized character."+er$}
end select
if a$<>"" then
Output$=format$("{0::-10}{1::-10} ", LineNo, ColumnNo)+a$+nl$
end if
End Sub
Sub checkerror()
if offset>lim then {
Error "End-of-line while scanning string literal. Closing string character not found before end-of-line."+er$
} else.if Ahead(nl$,offset) then {
Error "End-of-file while scanning string literal. Closing string character not found."+er$
}
End Sub
}
Module syntax_analyzer (b$){
enum tokens {
Op_add, Op_subtract, Op_not=5, Op_multiply=10, Op_divide, Op_mod,
Op_negate, Op_less, Op_lessequal, Op_greater, Op_greaterequal,
Op_equal, Op_notequal, Op_and, Op_or, Op_assign=100, Keyword_if=110,
Keyword_else, Keyword_while, Keyword_print, Keyword_putc, LeftParen, RightParen,
LeftBrace, RightBrace, Semicolon, Comma, Identifier, Integer, String, End_of_input
}
 
Inventory precedence=Op_multiply:=13, Op_divide:=13, Op_mod:=13, Op_add:=12, Op_subtract:=12
Append precedence, Op_negate:=14, Op_not:=14, Op_less:=10, Op_lessequal:=10, Op_greater:=10
Append precedence, Op_greaterequal:=10, Op_equal:=9, Op_notequal:=9, Op_assign:=-1, Op_and:=5
Append precedence, Op_or:=4
 
Inventory symbols=Op_multiply:="Multiply", Op_divide:="Divide", Op_mod:="Mod", Op_add:="Add"
Append symbols, Op_negate:="Negate", Op_not:="Not", Op_less:="Less", Op_subtract:="Subtract"
Append symbols, Op_lessequal:="LessEqual", Op_greater:="Greater", Op_greaterequal:="GreaterEqual"
Append symbols, Op_equal:="Equal", Op_notequal:="NotEqual", Op_and:="And", Op_or:="Or"
 
def lineNo, ColumnNo, m, line$, a, lim, cur=-1
const nl$=chr$(13)+chr$(10), Ansi=3
Dim lex$()
lex$()=piece$(b$,chr$(13)+chr$(10))
lim=dimension(lex$(),1)-1
op=End_of_input
flush
k=0
Try {
push (,) ' Null
getone(&op)
repeat
stmt(&op)
shift 2 ' swap two top items
push ("Sequence", array, array)
k++
until op=End_of_Input
}
er$=error$
if er$<>"" then print er$ : flush: break
Print "Ast"
Document Output$
prt_ast()
Push Output$
exit
clipboard Output$
Save.Doc Output$, "parse.t", Ansi
document parse$
Load.Doc parse$,"parse.t", Ansi
Report parse$
 
sub prt_ast(t)
if len(t)<1 then
Output$=";"+nl$
else.if len(t)=3 then
Output$=t#val$(0) +nl$
prt_ast(t#val(1)) : prt_ast(t#val(2))
else
Output$=t#val$(0) +nl$
end if
end sub
sub expr(p) ' only a number
local x=(,), prev=op
if op>=Identifier then
x=(line$,)
getone(&op)
else.if op=LeftParen then
paren_exp()
x=array
else.if op<10 then
getone(&op)
expr(precedence(int(Op_negate)))
read local y
if prev=Op_add then
x=y
else
if prev=Op_subtract then prev=Op_negate
x=(symbols(prev), y,(,))
End if
else
{error "??? "+eval$(op)}
end if
local prec
while exist(precedence, int(op))
prev=op : prec=eval(precedence)
if prec<14 and prec>=p else exit
getone(&op)
expr(prec+1) ' all operators are left associative (use prec for right a.)
x=(symbols(int(prev)), x, array)
End While
Push x
end sub
sub paren_exp()
expected(LeftParen)
getone(&op)
expr(0)
expected(RightParen)
getone(&op)
end sub
sub stmt(&op)
local t=(,)
if op=Identifier then
t=(line$)
getone(&op)
expected(Op_assign)
getone(&op)
expr(0)
read local rightnode
Push ("Assign",t,rightnode)
expected(Semicolon)
getone(&op)
else.if op=Semicolon then
getone(&op)
Push (";",)
else.if op=Keyword_print then
getone(&op)
expected(LeftParen)
repeat
getone(&op)
if op=String then
Push ("Prts",(line$,),(,))
getone(&op)
else
expr(0)
Push ("Prti", array,(,))
end if
t=("Sequence", t, array)
until op<>Comma
expected(RightParen)
getone(&op)
expected(Semicolon)
getone(&op)
push t
else.if op=Keyword_while then
getone(&op)
paren_exp()
stmt(&op)
shift 2
Push ("While",array, array)
else.if op=Keyword_if then
getone(&op)
paren_exp()
stmt(&op)
local s2=(,)
if op=Keyword_else then
getone(&op)
stmt(&op)
read s2
end if
shift 2
Push ("If",array ,("If",array,s2))
else.if op=Keyword_putc then
getone(&op)
paren_exp()
Push ("Prtc",array,t)
expected(Semicolon)
getone(&op)
else.if op=LeftBrace then
Brace()
else
error "Unkown Op"
end if
end sub
Sub Brace()
getone(&op)
while op<>RightBrace and op<>End_of_input
stmt(&op)
t=("Sequence", t, array)
end while
expected(RightBrace)
getone(&op)
push t
End Sub
Sub expected(what)
if not op=what then {Error "Expected "+eval$(what)+str$(LineNo)+","+Str$(ColumnNo)}
End Sub
sub getone(&op)
op=End_of_input
while cur<lim
cur++
line$=trim$(lex$(cur))
if line$<>"" then exit
end while
if cur=lim then exit sub
LineNo=Val(line$,"int",m)
line$=mid$(line$, m)
ColumnNo=Val(line$,"int",m)
line$=trim$(mid$(line$, m))
Rem : Print LineNo, ColumnNo
m=instr(line$," ")
if m>0 then op=Eval("."+leftpart$(line$, " ")) else op=Eval("."+line$)
end sub
}
Module CodeGenerator (s$){
Function code$(op$) {
=format$("{0::-6} {1}", pc, op$)
pc++
}
Function code2$(op$, n$) {
=format$("{0::-6} {1} {2}", pc, op$, n$)
pc+=5
}
Function code3$(op$,pc, st, ed) {
=format$("{0::-6} {1} ({2}) {3}", pc, op$, ed-st-1, ed)
}
 
Enum tok {
gneg, gnot, gmul, gdiv, gmod, gadd, gle, gsub, glt
gle, ggt, gge, geq, gne, gand, gor, gprtc, gprti, gprts,
gif, gwhile, gAssign, gSeq, gstring, gidentifier, gint, gnone
}
 
\\ Inventories are lists with keys, or keys/data (key must be unique)
\\ there is one type more the Invetory Queue which get same keys.
\\ But here not used.
Inventory symb="Multiply":=gmul, "Divide":=gdiv, "Mod":=gmod, "Add":=gadd
Append symb, "Negate":=gneg, "Not":=gnot,"Less":=glt,"Subtract":=gsub
Append symb, "LessEqual":=gle, "Greater":=ggt, "GreaterEqual":=gge, "Sequence":=gSeq
Append symb, "Equal":=geq, "NotEqual":=gne, "And":=gand, "Or":=gor, "While":=gwhile
Append symb, "Prtc":=gprtc,"Prti":=gprti,"Prts":=gprts, "Assign":=gAssign, "If":=gif
Append symb, "String":=gstring, "Identifier":=gidentifier, "Integer":=gint, ";", gnone
 
Inventory DataSet
\\ We set string as key. key maybe an empty string, a string or a number.
\\ so we want eash string to saved one time only.
Inventory Strings
 
Const nl$=chr$(13)+chr$(10), Ansi=3
Def z$, lim, line$, newvar_ok, i=0
Document message$=nl$
Global pc\\ functions have own scope, so we make it global, for this module, and childs.
 
Dim lines$()
s$=filter$(s$,chr$(9)) \\ exclude tabs
Lines$()=piece$(s$,nl$) \\ break to lines
lim=len(Lines$())
Flush ' empty stack (there is a current stack of values which we use here)
 
Load_Ast()
If not stack.size=1 Then Flush : Error "Ast not loaded"
AST=array \\ pop the array from stack
Document Assembly$, Header$
 
\\ all lines of assembly goes to stack. Maybe not in right order.
\\ Push statement push to top, Data statement push to bottom of stack
 
CodeGenerator(Ast)
Data code$("halt") ' append to end of stack
\\ So now we get all data (letters) from stack
While not empty
Assembly$=letter$+nl$
end while
\\ So now we have to place them in order
Sort Assembly$
 
\\ Let's make the header
Header$=format$("Datasize: {0} Strings: {1}", Len(Dataset),Len(strings))
\\ we use an iterator object, str^ is the counter, readonly, but Eval$() use it from object.
str=each(strings)
While str
Header$=nl$+Eval$(str)
End while
Assembly$=nl$
\\ insert to line 1 the Header
Insert 1 Assembly$=Header$
\\ Also we check for warnings
If len(message$)>2 then Assembly$="Warnings: "+nl$+message$
\\ So now we get a report
\\ (at each 3/4 of window's lines, the printing stop and wait for user response, any key)
Push Assembly$
Exit
Report Assembly$
Clipboard Assembly$
Save.Doc Assembly$, "code.t", Ansi
End
\\ subs have 10000 limit for recursion but can be extended to 1000000 or more.
Sub CodeGenerator(t)
 
If len(t)=3 then
select case t#val(0)
Case gSeq
CodeGenerator(t#val(1)) : CodeGenerator(t#val(2))
Case gwhile
{
local spc=pc
CodeGenerator(t#val(1))
local pc1=pc
pc+=5 ' room for jz
CodeGenerator(t#val(2))
data code3$("jz",pc1, pc1, pc+5)
data code3$("jmp",pc, pc, spc)
pc+=5 ' room for jmp
}
Case gif
{
CodeGenerator(t#val(1))
local pc1=pc, pc2
pc+=5
CodeGenerator(t#val(2)#val(1))
If len(t#val(2)#val(2))>0 then
pc2=pc
pc+=5
data code3$("jz",pc1, pc1, pc)
CodeGenerator(t#val(2)#val(2))
data code3$("jmp",pc2, pc2, pc)
else
data code3$("jz",pc1, pc1, pc)
end If
}
Case gAssign
{
CodeGenerator(t#val(2))
local newvar_ok=true
CodeGenerator(t#val(1))
}
case gneg to gnot, gprtc to gprts
CodeGenerator(t#val(1)) : data code$(mid$(eval$(t#val(0)),2))
case gmul to gor
{
CodeGenerator(t#val(1))
CodeGenerator(t#val(2))
data code$(mid$(eval$(t#val(0)),2))
}
End select
Else.if len(t)=2 then
select case t#val(0)
Case gString
{
local spos
If exist(strings,t#val$(1)) then
spos=eval(strings!)
else
append strings, t#val$(1)
spos=len(strings)-1
end If
Push code2$("push",str$(spos,0))
}
Case gInt
Push code2$("push",t#val$(1), pc)
Case gIdentifier
{
local ipos
If exist(dataset,t#val$(1)) then
ipos=Eval(dataset!) ' return position
else.if newvar_ok then
Append dataset, t#val$(1)
ipos=len(dataset)-1
else
message$="Variable "+t#val$(1)+" not initialized"+nl$
 
end If
If newvar_ok then
Push code2$("store","["+str$(ipos, 0)+"]")
else
Push code2$("fetch","["+str$(ipos, 0)+"]")
end If
}
end select
End If
End Sub
Sub Load_Ast()
If i>=lim then Push (,) : exit sub
do
line$=Trim$(lines$(i))
I++
tok$=piece$(line$," ")(0)
until line$<>"" or i>=lim
If tok$="Identifier" then
Push (gidentifier,trim$(Mid$(line$,11)))
else.if tok$="Integer" then
long n=Val(Mid$(line$,8)) ' check overflow
Push (gint, Trim$(Mid$(line$,8)))
else.if tok$="String" then
Push (gstring,Trim$(Mid$(line$,7)))
else.if tok$=";" then
Push (,)
Else
local otok=symb(tok$)
Load_Ast()
Load_Ast()
Shift 2
Push (otok,array, array)
End If
End Sub
}
Module Virtual_Machine_Interpreter (a$){
\\ function to extract string, replacing escape codes.
Function GetString$(a$) {
s=instr(a$, chr$(34))
m=rinstr(a$,chr$(34))-s
if m>1 then
\\ process escape codes
=format$(mid$(a$, s+1, m-1))
else
=""
end if
}
const nl$=chr$(13)+chr$(10)
\\ we can set starting value to any numbern where 0<=n<=232
enum op { halt_=232, add_, sub_, mul_, div_, mod_, not_, neg_, and_, or_, lt_,
gt_, le_, ge_, ne_, eq_, prts_, prti_, prtc_, store_, fetch_, push_,
jmp_, jz_
}
exit_now=false
Inventory func=halt_:=lambda->{exit_now=true}
Append func, push_:=lambda->{sp--:return stack_, sp:=eval(code_, pc as long):pc+=4}
Append func, jz_:=lambda->{
sp++: if eval(stack_, sp-1)=0 then pc=eval(code_, pc as long) else pc+=4
}
Append func, jmp_:=lambda->{pc=eval(code_, pc as long)}
Append func, fetch_:=lambda->{sp--:Return stack_, sp:=eval(stack_, eval(code_, pc as long)):pc+=4}
Append func, store_:=lambda->{Return stack_, eval(code_, pc as long):=eval(stack_, sp):sp++:pc+=4}
Append func, add_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))+sint(eval(stack_, sp))):sp++}}
Append func, sub_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))-sint(eval(stack_, sp))):sp++}}
Append func, mul_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))*sint(eval(stack_, sp))):sp++}}
Append func, div_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1)) div sint(eval(stack_, sp))):sp++}}
Append func, mod_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1)) mod sint(eval(stack_, sp))) :sp++}}
Append func, not_:=lambda->{Return stack_, sp:=if(eval(stack_, sp)=0->uint(-1),0)}}
Append func, neg_:=lambda->{Return stack_, sp:=uint(-sint(eval(stack_, sp)))}}
Append func, and_:=lambda->{Return stack_, sp+1:=binary.and(eval(stack_, sp+1),eval(stack_, sp)):sp++ }
Append func, or_:=lambda->{Return stack_, sp+1:=binary.or(eval(stack_, sp+1),eval(stack_, sp)):sp++ }
Append func, lt_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))<sint(eval(stack_, sp))->-1, 0)):sp++}}
Append func, gt_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))>sint(eval(stack_, sp))->-1, 0)):sp++}}
Append func, le_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))<=sint(eval(stack_, sp))->-1, 0)):sp++}}
Append func, ge_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))>=sint(eval(stack_, sp))->-1, 0)):sp++}}
Append func, ne_:=lambda->{Return stack_, sp+1:=uint(if(eval(stack_, sp+1)<>eval(stack_, sp)->-1, 0)):sp++}}
Append func, eq_:=lambda->{Return stack_, sp+1:=uint(if(eval(stack_, sp+1)=eval(stack_, sp)->-1, 0)):sp++}}
Append func, prts_:=lambda->{Print #-2, string$(eval(stack_,sp));: Refresh:sp++}}
Append func, prti_:=lambda->{Print #-2, str$(sint(eval(stack_,sp)),0);: Refresh:sp++}}
Append func, prtc_:=lambda->{Print #-2, chrcode$(eval(stack_,sp));: Refresh:sp++}}
Rem : Form 120, 60 ' change console width X height to run Ascii Mandlebrot example
\\ change Report with Print #-2,(report stop when scrolling 3/4 of height of console, waiting key or mouse key to continue)
Print #-2, "Virtual Assembly Code:"+{
}+a$
Print "Prepare Byte Code"
 
\\ get datasize
a$=rightpart$(a$, "Datasize:")
m=0
data_size=val(a$, "int", m)
a$=mid$(a$, m)
\\ make stack
if data_size>0 then Buffer Clear stack_ as long*data_size
\\ dim or redim buffer append 1000 long as is.
Buffer stack_ as long*(1000+data_size)
\\ get strings
a$=rightpart$(a$, "Strings:")
m=0
strings=val(a$, "int", m)
a$=rightpart$(a$, nl$)
 
if strings>0 then
Dim strings$(strings)
for i=0 to strings-1
strings$(i)=GetString$(leftpart$(a$, nl$))
a$=rightpart$(a$, nl$)
Next i
End if
buffer clear code_ as byte*1000
do
m=0
offset=val(a$,"int", m)
if m<0 then exit
a$=mid$(a$,m)
line$=trim$(leftpart$(a$,nl$))
if line$="" then line$=trim$(a$) else a$=trim$(rightpart$(a$, nl$))
op$=if$(instr(line$," ")>0->leftpart$(line$," "), line$)
if not valid(eval(op$+"_")) then exit
opc=eval(op$+"_")
Return code_, offset:=opc
if opc>=store_ then
line$=rightpart$(line$," ")
select case opc
case store_, fetch_
Return code_, offset+1:=val(rightpart$(leftpart$(line$,"]"),"[")) as long : offset+=4
case push_
Return code_, offset+1:=uint(val(line$)) as long : offset+=4
case jz_, jmp_
Return code_, offset+1:=val(rightpart$(line$,")")) as long : offset+=4
end select
end if
Always
\\Print "Press any key" : Push key$ : Drop
\\ Prepare VM
let pc=0, sp=len(stack_) div 4
do
b=func(eval(code_, pc))
pc++
call local b()
until exit_now
Print "done"
}
Push {
{
/*
This is an integer ascii Mandelbrot generator
*/
left_edge= -420;
right_edge=300;
top_edge=300;
bottom_edge = -300;
x_step=7;
y_step=15;
 
max_iter=200;
 
y0 = top_edge;
while (y0 > bottom_edge) {
x0 = left_edge;
while (x0 < right_edge) {
y = 0;
x = 0;
the_char = ' ';
i = 0;
while (i < max_iter) {
x_x = (x * x) / 200;
y_y = (y * y) / 200;
if (x_x + y_y > 800 ) {
the_char = '0' + i;
if (i > 9) {
the_char = '@';
}
i = max_iter;
}
y = x * y / 100 + y0;
x = x_x - y_y + x0;
i = i + 1;
}
putc(the_char);
x0 = x0 + x_step;
}
putc('\n');
y0 = y0 - y_step;
}
}
}
 
Form ! 120, 60
Refresh
Print "Lexical Analyzer" : Refresh
lexical_analyzer
Print "Syntax Analyzer" : Refresh
syntax_analyzer
Print "Code Generator" : Refresh
CodeGenerator
Virtual_Machine_Interpreter
Set Fast 'restore speed setting
}
CompilerExample