; ================================================================
;   Example rom with c code for a Z80 system
;   Copyright  (c)  Günter Woigk 1994 - 2017
;                   mailto:kio@little-bat.de
; ================================================================

#target rom

_rom_start::        equ 0
_rom_end::          equ 0x4000
_ram_start::        equ 0x4000
_ram_end::          equ 0x10000
_min_heap_size::    equ 0x1000


; ================================================================
; Define ordering of code segments in ram:
; these segments produce code in the output file!
; ================================================================

#code   _HEADER,_rom_start
#code   _GSINIT             ; init code: the compiler adds some code here and there as required
#code   _HOME               ; code that must not be put in a bank switched part of memory.
#code   _CODE               ; most code and const data go here
#code   _CABS,*,0           ; referenced but never (?) actually used by sdcc
#code   _GSFINAL,*,0        ; referenced but never (?) actually used by sdcc
#code   _INITIALIZER        ; initializer for initialized data in ram
#code   _ROM_PADDING        ; pad rom file up to rom end
        defs  _rom_end-$$


; ================================================================
; Define variables in ram:
; note: data segments do not produce actual code
; ================================================================

#data   _DATA, _ram_start   ; uninitialized data
#data   _INITIALIZED        ; data initialized from _INITIALIZER
#data   _DABS,*,0           ; referenced but never (?) actually used by sdcc
#data   _RSEG,*,0           ; referenced but never (?) actually used by kcc

#data   _HEAP               ; heap:
__sdcc_heap_start:          ; --> sdcc _malloc.c
        ds  _min_heap_size  ; minimum required size
        ds  _ram_end-$-1        ; add all unused memory to the heap
__sdcc_heap_end:            ; --> sdcc _malloc.c
        ds  1


; ================================================================
;   _HEADER segment:
;   starts at 0x0000
; ================================================================

;   reset vector
;   RST vectors
;   INT vector (IM 1)
;   NMI vector

#CODE _HEADER

; reset vector
RST0::  di
        ld      sp,_ram_end
        jp      init
        defs    0x08-$

RST1::  ret
        defs    0x10-$

RST2::  ret
        defs    0x18-$

RST3::  ret
        defs    0x20-$

RST4::  ret
        defs    0x28-$

RST5::  ret
        defs    0x30-$

RST6::  ret
        defs    0x38-$

; maskable interrupt handler in interrupt mode 1:
RST7::  ei                          ; add INT handler here
        reti


; init:
; globals and statics initialization
; starts with copying the fixed data:

init:   ld  bc,_INITIALIZER_size    ; length of segment _INITIALIZER
        ld  de,_INITIALIZED         ; start of segment _INITIALIZED
        ld  hl,_INITIALIZER         ; start of segment _INITIALIZER
        ld  a,b
        or  c
        jr  z,$+4
        ldir

        call    _GSINIT             ; Initialise global variables
        call    _main               ; execute main()

; shut down:
; if main() returns then something went wrong.
; call debugger and on exit restart system.

_exit:: di
        call    NMI
        rst     0

; non maskable interrupt:
; e.g. call debugger and on exit resume.

        defs    0x66-$
NMI::   ld      a,i                 ; add NMI vector here
        push    af
        pop     af
        ret     po                  ; interrupts were disabled
        ei                          ; else re-eanble interrupts
        ret


; ================================================================
; the payload:
; ================================================================

#CPATH   "../sdcc/bin/sdcc"
#CFLAGS  $CFLAGS --nostdinc -I../sdcc/include   ; add some flags for sdcc
#INCLUDE "main.c"                               ; compile & include file "main.c"
#INCLUDE LIBRARY "../sdcc/lib/"                 ; resolve missing global labels


; ================================================================
; calculate some last labels:
; ================================================================

#CODE _GSINIT

        ret                         ; final ret from initialization code