Nut-Compiler completion kit

You must upload the updated "nut31.zip" to be used as the tool. The Nut-completion kit ("nut2.txt") is a partially implemented Nut-compiler-in-nut. Your task is to add some language features to this compiler. You are assumed to be able to

1)   Edit the compiler source (in nut) using an appropriate editor (should have parenthesis matching check).
2)    Compile the source successfully.
3)    Test the modified program, know how to debug it.

All of these have to be done from DOS window.

To add "let" "enum" and "string" you must define the following functions: doGvar, doEnum, doString and parseEnum. (I have defined parseLet for your example)

in parseName

doGvar op arg     ; is similar to doVar
                  ; the mapping is

op = SET   makeAtom ST.arg
op = SETV makeAtom STY.arg
op = VEC   makeAtom LDY.arg
return atom

doEnum n
return makeAtom LIT.n

doString s
return makeAtom STR mkSTR s

mkSTR allocate string space from DS (mem[]) and copy string s to there. What tok looks like? It is a string prefixed with ". That is how tokeniser scan a token. Therefore doString is passed with (+ tok 1) which mean it skips the first ".

parseEnum
tokenise        ; to get the starting number
k = atoi tok
tokenise        ; scan each token until ")"
while tok string-not-eq ")"
    update symbol table with tok, tyEnum, val k
    k = k + 1
    tokenise

to update symbol table
you must install tok to get index (handle)
(set idx (install tok))

The user code segment (the n-code that being generated) resides at "start" (which is instantiated by "sys 9" asking the underlying virtual machine where "heapFree" is). At the end, to output object, you have to relocate code segment to start at 2. To relocate code segment two functions are defined:

1) reloc, to rename every call to the new address.
2) shift, to relocate dot-pair to the new address.

This is done in "outobj2". It also output the data segment. The object will be accept by "nsim31" properly. Read "outobj" and "outobj2" to see what has been changed.

Try to use this nut-compiler, "nut2.txt", to compile the example "t2.txt" when run it with "nsim31" it outputs "string12".
Try it on two other examples "bubblen.txt", "quick1.txt" which are sorting programs.

You can compare the object outputted from your compiler "nut2.txt" with the correct one outputted from "nut31", "t2.obj". It must be the same, except the location in symbol table (which is not used in running the program by "nsim31").

28 June 2006