;This file resolves "init" and "author" as defined
;in sm.expansion.h.

;This code is compiled into a separate initialization
;module, so it is run once and then flushed from
;memory.  Make sure that no data that is stored in
;this file is used during normal operation of SoftMMU.

;Remember that all source is #included together
;during compilation, so keep label names unique by
;including the expansion name in the label name.

;tsp_exp is defined, before #including this file, as
;        the offset into the TSP where the expansion-
;        specific bytes have been reserved.

;------
;Readme
;------

;Not a routine, just text.  Include name, contact
;information, and release date, along with any other
;README-type stuff you wish to include.  Since this
;isn't compiled into the kernel, don't worry about
;size considerations.

readme_skeleton:
.byte "Sample skeleton source code for "
.byte "implementing a memory expansion "
.byte "for SoftMMU.  This code should not "
.byte "be compiled!",$0a,$0a
.byte "Released on October 27, 1999 by",$0a
.byte "White Flame (aka David Holz)",$0a
.byte "http://fly.to/theflame",$00

;----
;Init
;----

init_skeleton:

  ;There's 8 bytes of userzp allocated, but the 1st
  ;two bytes are used by sm_getfreelistpage (below).
  ;If you need more, specifically allocate it with
  ;set_zpsize.

  ;PRESERVE .X THROUGHOUT THIS ROUTINE.  It holds
  ;the expansion number for the current module.

  ;1) Detect how much memory is present in the device.
  ;   If it can't be detected or there is any error,
  ;   return with carry set (and .X preserved).  This
  ;   will flag SoftMMU that the memory source is
  ;   unavailable.

  ;2) To have SoftMMU automatically allocate memory
  ;   for this device, set up a standard free list
  ;   page.  This routine uses also sets up a pointer
  ;   to the free list page at userzp.

  jsr sm_getfreelistpage
  bcs +  ;just in case.

  ;2a) If a free list page is set up, it must be
  ;    initialized to contain at least 1 free list
  ;    structure to tell SoftMMU that the memory
  ;    is free to use.

  ldy #$00        ;Set up the structure
  lda #<length
  sta (userzp),y
  iny
  lda #>length
  sta (userzp),y
  iny
  lda #<start
  sta (userzp),y
  iny
  lda #>start
  sta (userzp),y
  iny

  tya             ;Set up free list page info
  sta sm_top,x
  sta sm_open,x

  ;If a free list page is not used, SoftMMU will
  ;rely on the "xalloc" and "xfree" pointers set
  ;up in the sm.expansion.h file to allocate pages.
  ;Initialize anything that those routines need
  ;to run.

+ rts