git.sur5r.net Git - cc65/blob - libsrc/gamate/crt0.s

   1
   2         .export         __STARTUP__ : absolute = 1      ; Mark as startup
   3
   4         .import         initlib, donelib, callmain
   5         .import         push0, _main, zerobss, copydata
   6
   7         .import         IRQStub
   8
   9         ; Linker generated symbols
  10         .import         __RAM_START__, __RAM_SIZE__
  11         .import         __ROM_START__, __ROM_SIZE__
  12         .import         __STARTUP_LOAD__,__STARTUP_RUN__, __STARTUP_SIZE__
  13         .import         __CODE_LOAD__,__CODE_RUN__, __CODE_SIZE__
  14         .import         __RODATA_LOAD__,__RODATA_RUN__, __RODATA_SIZE__
  15
  16         .include        "zeropage.inc"
  17         .include        "gamate.inc"
  18
  19         .segment "STARTUP"
  20
  21         .word 0                                         ; +00 checksum from 7000-7fff (simple 8bit adds)
  22         .byte 1, 0, 1                                   ; +02 flags
  23         .byte "COPYRIGHT BIT CORPORATION", 0, $ff       ; +05 copyright
  24         ; system vectors
  25         jmp     reset                                   ; +20 reset entry
  26         jmp     nmi                                     ; +23 nmi entry
  27         jmp     IRQStub                                 ; +26 irq entry (135 hz)
  28
  29 ;-------------------------------------------------------------------------------
  30 reset:
  31         ; setup the CPU and System-IRQ
  32
  33         ; Initialize CPU
  34         sei
  35         cld
  36
  37         ; Setup stack and memory mapping
  38         ldx     #$FF            ; Stack top ($01FF)
  39         txs
  40
  41         ; Clear the BSS data
  42         jsr     zerobss
  43
  44         ; Copy the .data segment to RAM
  45         jsr     copydata
  46
  47         ; setup the stack
  48         lda     #<(__RAM_START__+__RAM_SIZE__)
  49         sta     sp
  50         lda     #>(__RAM_START__+__RAM_SIZE__)
  51         sta     sp + 1
  52
  53         ; Call module constructors
  54         jsr     initlib
  55
  56         cli     ; allow IRQ only after constructors have run
  57
  58         ; Pass an empty command line
  59         jsr     push0           ; argc
  60         jsr     push0           ; argv
  61
  62         ldy     #4              ; Argument size
  63         jsr     _main           ; call the users code
  64
  65         ; Call module destructors. This is also the _exit entry.
  66 _exit:
  67         jsr     donelib         ; Run module destructors
  68
  69         ; reset (start over)
  70         jmp     reset
  71
  72         .export initmainargs
  73 initmainargs:
  74         rts
  75
  76 ;-------------------------------------------------------------------------------
  77 nmi:
  78         rts