mirror of
https://github.com/cc65/cc65.git
synced 2024-10-31 04:04:49 +00:00
364 lines
10 KiB
ArmAsm
364 lines
10 KiB
ArmAsm
;
|
|
; Extended Memory Driver for the Action Replay/Retro Replay RAM
|
|
;
|
|
; original Version 1.0 by Johannes Braun 2006-08-22 <hannenz@freenet.de>
|
|
; ------------------------------------------------------------------------
|
|
|
|
.include "zeropage.inc"
|
|
|
|
.include "em-kernel.inc"
|
|
.include "em-error.inc"
|
|
|
|
.macpack generic
|
|
.macpack module
|
|
|
|
; ------------------------------------------------------------------------
|
|
|
|
c64_ram = ptr1 ; use some more expressive identifiers...
|
|
rr_ram = ptr2
|
|
len = ptr3
|
|
aux = ptr4
|
|
temp = tmp1
|
|
|
|
Lo_Mem = $0100 ; location of Lo_Code (must be below $1000 or above $e000)
|
|
|
|
RRMODE_OFF = $02
|
|
RRMODE_CART_RAM = $23
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Header. Includes jump table
|
|
|
|
module_header _c64_rrr_emd
|
|
|
|
; Driver signature
|
|
|
|
.byte $65, $6d, $64 ; "emd"
|
|
.byte EMD_API_VERSION ; EM API version number
|
|
|
|
; Library reference
|
|
|
|
.addr $0000
|
|
|
|
; Jump table
|
|
|
|
.addr INSTALL
|
|
.addr UNINSTALL
|
|
.addr PAGECOUNT
|
|
.addr MAP
|
|
.addr USE
|
|
.addr COMMIT
|
|
.addr COPYFROM
|
|
.addr COPYTO
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Data.
|
|
|
|
.bss
|
|
window: .res 256 ; the memory window (256 bytes)
|
|
pagecount: .res 1 ; Number of available pages
|
|
|
|
.rodata
|
|
dummy:
|
|
.word window ; a "pseudo"-em_copy_struct, used by em_map/ em_commit
|
|
.byte 0 ; to pass over to COPYTO/COPYFROM
|
|
curpage:
|
|
.byte $ff ; just this byte is changed according to the desired page
|
|
.byte 0
|
|
.word 256
|
|
|
|
.code
|
|
|
|
;----------------------------------------------------------------------------------------
|
|
;unsigned char __fastcall__ em_install(void *driver);
|
|
;returns an error code
|
|
;----------------------------------------------------------------------------------------
|
|
INSTALL:
|
|
ldx #c2-c1
|
|
: lda c1,x
|
|
sta Lo_Mem,x
|
|
dex
|
|
bpl :-
|
|
;ldx #$ff
|
|
stx curpage ; invalidate current page
|
|
|
|
ldy #RRMODE_OFF
|
|
sei
|
|
jmp Lo_Mem+8 ; jump to the code below
|
|
|
|
; copied to Lo_Mem
|
|
c1:
|
|
|
|
;detectmodes:
|
|
.byte RRMODE_CART_RAM | $00
|
|
.byte RRMODE_CART_RAM | $08
|
|
.byte RRMODE_CART_RAM | $10
|
|
.byte RRMODE_CART_RAM | $18
|
|
.byte RRMODE_CART_RAM | $80
|
|
.byte RRMODE_CART_RAM | $88
|
|
.byte RRMODE_CART_RAM | $90
|
|
.byte RRMODE_CART_RAM | $98
|
|
|
|
; first save c64 memory
|
|
lda $8888
|
|
pha
|
|
|
|
; tag c64 memory
|
|
lda #$00
|
|
sta $8888
|
|
|
|
ldx #$07
|
|
:
|
|
; try accessing rr-ram
|
|
;lda detectmodes, x
|
|
lda Lo_Mem, x
|
|
sta $de00
|
|
|
|
; tag (hopefully) rr memory
|
|
txa
|
|
ora #$80
|
|
sta $8888
|
|
|
|
dex
|
|
bpl :-
|
|
|
|
;ldy #RRMODE_OFF
|
|
sty $de00
|
|
|
|
; now if C64 memory is $80, there is no AR/RR
|
|
; if C64 memory is $00, there is a AR/RR.
|
|
|
|
lda $8888
|
|
beq detectpages
|
|
|
|
lda #0
|
|
beq hasnopages
|
|
|
|
detectpages:
|
|
; we can now read the highest available bank nr from the highest bank :)
|
|
|
|
lda #RRMODE_CART_RAM | $98
|
|
sta $de00
|
|
|
|
ldx $8888
|
|
inx
|
|
txa
|
|
|
|
; 8k = 32 pages
|
|
asl
|
|
asl
|
|
asl
|
|
asl
|
|
asl
|
|
|
|
hasnopages:
|
|
|
|
;ldy #RRMODE_OFF
|
|
sty $de00 ; c64 ram again
|
|
|
|
sta pagecount
|
|
|
|
; restore c64 memory
|
|
pla
|
|
sta $8888
|
|
|
|
cli
|
|
|
|
ldx pagecount
|
|
beq no
|
|
|
|
; no error
|
|
lda #0
|
|
tax
|
|
rts
|
|
|
|
no:
|
|
lda #4 ; return #4: error code for "device not present"
|
|
rts
|
|
c2:
|
|
|
|
;----------------------------------------------------------------------------------------
|
|
;void em_uninstall(void);
|
|
;----------------------------------------------------------------------------------------
|
|
UNINSTALL:
|
|
return_null:
|
|
lda #$00
|
|
tax
|
|
rts
|
|
|
|
;----------------------------------------------------------------------------------------
|
|
;unsigned __fastcall__ em_pagecount(void);
|
|
;----------------------------------------------------------------------------------------
|
|
PAGECOUNT:
|
|
lda pagecount ; always return 32kb (128 pages)
|
|
ldx #$00
|
|
rts
|
|
|
|
;----------------------------------------------------------------------------------------
|
|
;void* __fastcall__ em_use(unsigned page);
|
|
;----------------------------------------------------------------------------------------
|
|
USE:
|
|
cmp #$80 ; valid page?
|
|
bcs return_null ; no, return NULL pointer
|
|
sta curpage ; set to current page
|
|
return_win:
|
|
lda #<window ; return pointer to window
|
|
ldx #>window
|
|
return: rts
|
|
|
|
;----------------------------------------------------------------------------------------
|
|
;void* __fastcall__ em_map(unsigned page);
|
|
;----------------------------------------------------------------------------------------
|
|
MAP:
|
|
cmp pagecount
|
|
bcs return_null
|
|
sta curpage
|
|
lda #<dummy ; load .A/.X with adress of data for COPYFROM-call (which expects the
|
|
ldx #>dummy ; adress in .A/.X)
|
|
jsr COPYFROM
|
|
bcs return_win ; function returns pointer to window (returns always with carry set!)
|
|
|
|
;----------------------------------------------------------------------------------------
|
|
;void __fastcall__ em_commit(void);
|
|
;----------------------------------------------------------------------------------------
|
|
COMMIT:
|
|
lda curpage
|
|
cmp pagecount
|
|
bcs return
|
|
lda #<dummy ; load .A/.X with adress of data for COPYTO-call (which expects the
|
|
ldx #>dummy ; adress in .A/.X)
|
|
|
|
;----------------------------------------------------------------------------------------
|
|
;void __fastcall__ em_copyto (struct em_copy *copy_data);
|
|
;----------------------------------------------------------------------------------------
|
|
COPYTO:
|
|
jsr get_struct_data ;read the parameters passed in the em_struct pointed to by .A/.X upon call
|
|
|
|
;copy the main copyto routine into Lo_Mem
|
|
|
|
ldy #Lo_Code1_End - Lo_Code1
|
|
: lda Lo_Code1-1,y
|
|
sta Lo_Mem-1,y
|
|
dey
|
|
bne :-
|
|
COMMON:
|
|
sei
|
|
jmp Lo_Mem
|
|
|
|
;this part will be executed in Lo_Mem (!) by COPYFROM
|
|
|
|
Lo_Code2:
|
|
; copy byte rr -> c64
|
|
stx $de00 ;map in rr-ram
|
|
lda (rr_ram),y ;get byte from rr-ram
|
|
sty $de00 ;RR-ROM will be mapped to $8000-$a000 but write access will go to c64-ram anyway!!
|
|
sta (c64_ram),y ;and write to c64-ram
|
|
nop ;pad to same size as Lo_Code1
|
|
nop
|
|
Lo_Code2_End:
|
|
|
|
|
|
;this part will be executed in Lo_Mem (!) by COPYTO
|
|
|
|
Lo_Code1:
|
|
; copy byte c64 -> rr
|
|
lda (c64_ram),y ;read 1 byte from c64-ram
|
|
stx $de00 ;map in rr-ram
|
|
sta (rr_ram),y ;write byte to rr-ram
|
|
lda #$02 ;map in c64-ram again
|
|
sta $de00
|
|
;12 bytes
|
|
|
|
;this part is common for both COPYFROM/COPYTO and executed in Lo_Mem, too
|
|
|
|
Lo_Code_Common:
|
|
inc c64_ram ;increase pointers
|
|
bne :+
|
|
inc c64_ram+1
|
|
: inc rr_ram
|
|
bne @skip
|
|
inc rr_ram+1
|
|
lda rr_ram+1
|
|
cmp #$a0 ;wrap around 16k boundary in rr-ram window ($8000-$a000)
|
|
bne @skip
|
|
|
|
lda #$80 ;reset pointer to $8000
|
|
sta rr_ram+1
|
|
txa ;adjust value in .X to map in next 16k-bank in rr-ram
|
|
adc #7 ;carry is set because of former CMP, so it adds 8
|
|
tax
|
|
;27 bytes
|
|
@skip: lda c64_ram
|
|
cmp len
|
|
lda c64_ram+1
|
|
sbc len+1
|
|
bcc Lo_Code1
|
|
lda #2 ;CHANGE to LDA #0 if driver is called from ROM
|
|
sta $de00
|
|
cli
|
|
rts ;17 bytes = 56 bytes Lo_Code ($38)
|
|
Lo_Code1_End:
|
|
;----------------------------------------------------------------------------------------
|
|
;void __fastcall__ em_copyfrom(struct em_copy *copy_data);
|
|
;copy from extended memory into linear memory
|
|
;----------------------------------------------------------------------------------------
|
|
COPYFROM:
|
|
jsr get_struct_data
|
|
|
|
ldy #Lo_Code2_End - Lo_Code2 ;copy routine into Lo_Mem
|
|
: lda Lo_Code2-1,y
|
|
sta Lo_Mem-1,y
|
|
dey
|
|
bne :-
|
|
ldy #Lo_Code1_End-Lo_Code_Common
|
|
: lda Lo_Code_Common-1,y
|
|
sta Lo_Mem+11,y
|
|
dey
|
|
bne :-
|
|
beq COMMON ;and execute...
|
|
;----------------------------------------------------------------------------------------
|
|
;read the struct data located at (.A/.X)
|
|
;and setup parameters for stash/ fetch operation
|
|
;----------------------------------------------------------------------------------------
|
|
get_struct_data:
|
|
|
|
;read and process the values from the em_copy struct passed to as parameters rameter to the
|
|
;functions em_copyto and em_copyfrom
|
|
|
|
sta aux ;store adress of struct (passed in .A/.X) into a zp pointer
|
|
stx aux+1
|
|
ldy #0 ;index 0
|
|
|
|
lda (aux),y ;read c64-adress lo
|
|
sta c64_ram
|
|
iny
|
|
lda (aux),y ;read c64-adress hi
|
|
sta c64_ram+1 ;(c64_ram) --> points to c64-adress space
|
|
iny
|
|
lda (aux),y ;read rr-adress lo
|
|
sta rr_ram
|
|
iny
|
|
lda (aux),y ;rr-adress hi
|
|
pha ;remember
|
|
and #$1f
|
|
ora #$80 ;adjust into 16k-window ($8000-$a000)
|
|
sta rr_ram+1
|
|
pla ;re-get hi byte of rr-adress
|
|
and #$60 ;isolate bits 5 and 6
|
|
lsr
|
|
lsr ;shift into bits 3 and 4
|
|
ora #$23 ;set bit 5 (select ram) and 1+2 (game/exrom setting for ULTIMAX-mode)
|
|
tax ;.X has now the value to write into $de00 to acess rr-ram at desired 16k-bank
|
|
iny
|
|
iny ;skip unused byte
|
|
lda (aux),y ;read length lo-byte
|
|
clc
|
|
adc c64_ram ;add to c64-addres
|
|
sta len
|
|
iny
|
|
lda (aux),y ;length hi-byte
|
|
adc c64_ram+1
|
|
sta len+1 ;tmp2: length, tmp3 contains end adress of transfer in c64-ram.
|
|
rts
|
|
;55 bytes
|
|
|