LUnix-Assembler (luna)

Many people would like to write some code for the little C64/128 but don't have the equipment to do so. So i decided to write a small (and therefore very portable) assembler in a subset of ansi-C. This assembler compiles without modifications on every (GNU-) C-compiler.

Additional this assembler is optimized to generate LUnix-applications. This is done by including a LUnix-binary-header-generator. This is why all new LUnix-applications will be in luna-format. Also the next version of the LUnix-kernel will be in this format (4400 lines yet! :-)

The sourcecode is around 1800 lines of C.

If you have compiled luna on an other system, especially systems that come without a c-compiler, please email me the executable, to include it here.

How to use luna:

Luna just assembles a source (text) file into a destination (binary) file which is executable on a C64/128. There is no editor included! The inputfile may be written with every text-editor that saves files in plain ascii-format.

There is also a ascii-documentation file

Source-format: (look into the ascii documentation for more)

• Comments are seperated by a leading ";"
• Label definitions look like
  • <label>:
  • <label> equ <expression>
• Expressions look like
  • <value>[{+,-,<,>,&,|}<value>]*
  • with <value>={[#]decimal,$hex,%bin,<label>,"<char>",*}
  Expressions may be preceeded by "<" to select the lower byte, or ">" to select the higher byte of a 16bit-expression.
• Special assembler-commands
  • .byte <expression>[,<expression>]*
  • .word <expression>[,<expression>]*
  • .longword <expression>[,<expression>]*
  • .asc "string\n\0"
  • .head "cmd-name" [<ZP-label>[,<ZP-label>]*] - insert LUnix-header and switch to LUnix-mode
  • .org <expression> - sets start address
  • .buf <expression> - insert #n (empty) bytes
  • .code - enter code-area (only in LUnix-mode)
  • .data - enter data-area (only in LUnix-mode)
  • .endofcode - no more code (enter data-area, only in LUnix-mode)
  • .newpage - align to start of (next) page
  • .global - declare a label global, a list of all globals and their value will be saved after compilation.
• Special labels (only used in LUnix-mode)
  • _base - Startaddress of codesegment
  • _init - Must point to init-routine
  • _cleanup - Can point to a cleanup-routine (called by kill)
  • _sig.killedparent - Can point to a handler
  • _sig.killedchild - Can point to a handler
  • _sig.userbreak - Can point to a handler
• Shortrange labels can be defined by a leading "+" for forward or "-" for backward references (leading a assembler command). So "jmp +" will jump to the next "+"-reference and "jmp -" to the latest "-"-reference. The same way "jmp ++" will jump to the second next "+"-marker and so on.

A simple example

The classic example is the "Hello World"-program, so this is my first example for luna also.

This is the sourcecode located in a file named "hello.a" :

  ; This is a simple "hello world" program
  ; for LUnix

  .header "hello"                ; "hello" is the name that will be displayed
                                 ; by "ps" in LUnix

          strout equ $905d       ; value of the 2 used system-vectors
          bye    equ $9018
          stdout equ _base+2     ; _base is startadress of codesegment
                                 ; and will be initialized by the assembler.

  _init:  ldx  stdout            ; load standard output-stream-ID
          jsr  strout            ; call "string output"
          bit  text_hello        ; pass text-pointer to strout 

          lda  #0                ; exitcode 0 (no error)
          jmp  bye               ; end program

          .endofcode             ; end of code

  text_hello:
          .asc "Hello, world!\n\0"

Running the assembler by typing "luna hello.a hello" will produce this output:

This is the code generated by luna (in file "hello"):

The lines marked with "*" are generated automatically by luna, they realize the header that Lunix needs to load and run a program.

The program "hello" can now be started by the LUnix-shell by just typing "hello":

If you have suggestions or comments contact me