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|
;
; Extended memory driver for the Apple II auxiliary memory
;
; Stefan Haubenthal, 2003-12-12
; Ullrich von Bassewitz, 2002-12-02
;
.include "zeropage.inc"
.include "em-kernel.inc"
.include "em-error.inc"
.macpack module
; ------------------------------------------------------------------------
; Header. Includes jump table
.ifdef __APPLE2ENH__
module_header _a2e_auxmem_emd
.else
module_header _a2_auxmem_emd
.endif
; 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
; ------------------------------------------------------------------------
; Constants
BASE = $0200
AUXCARD = $C30C ; Card signature
AUXMOVE = $C311 ; Auxiliary move routine
PAGES = ($C000 - BASE) / 256
; ------------------------------------------------------------------------
; Data.
.data
curpage: .byte $FF ; Current page number (invalid)
.bss
window: .res 256 ; Memory "window"
.code
; ------------------------------------------------------------------------
; INSTALL routine. Is called after the driver is loaded into memory. If
; possible, check if the hardware is present and determine the amount of
; memory available.
; Must return an EM_ERR_xx code in a/x.
;
INSTALL:
ldx #0
lda AUXCARD
and #$f0
cmp #$80
bne @L1
lda #EM_ERR_OK
rts
@L1: lda #EM_ERR_NO_DEVICE
; rts
; ------------------------------------------------------------------------
; UNINSTALL routine. Is called before the driver is removed from memory.
; Can do cleanup or whatever. Must not return anything.
;
UNINSTALL:
rts
; ------------------------------------------------------------------------
; PAGECOUNT: Return the total number of available pages in a/x.
;
PAGECOUNT:
lda #<PAGES
ldx #>PAGES
rts
; ------------------------------------------------------------------------
; MAP: Map the page in a/x into memory and return a pointer to the page in
; a/x. The contents of the currently mapped page (if any) may be discarded
; by the driver.
;
MAP: sta curpage ; Remember the new page
clc
adc #>BASE
sta ptr1+1
ldy #$00
sty ptr1
lda #<window
sta ptr2
lda #>window
sta ptr2+1
; Transfer one page
clc ; Direction flag
jsr transfer ; Transfer one page
; Return the memory window
lda #<window
ldx #>window ; Return the window address
; Done
done: rts
; ------------------------------------------------------------------------
; USE: Tell the driver that the window is now associated with a given page.
USE: sta curpage ; Remember the page
lda #<window
ldx #>window ; Return the window
rts
; ------------------------------------------------------------------------
; COMMIT: Commit changes in the memory window to extended storage.
COMMIT: lda curpage ; Get the current page
cmp #$FF
beq done ; Jump if no page mapped
clc
adc #>BASE
sta ptr2+1
ldy #$00
sty ptr2
lda #<window
sta ptr1
lda #>window
sta ptr1+1
lda #<$FF
sta ptr4
lda #>$FF
sta ptr4+1
sec ; Direction flag
; Transfer one page/all bytes
transfer:
php
clc
lda ptr1
sta $3C
adc ptr4
sta $3E
lda ptr1+1
sta $3D
adc ptr4+1
sta $3F
lda ptr2
sta $42
lda ptr2+1
sta $43
plp
jmp AUXMOVE
; ------------------------------------------------------------------------
; COPYFROM: Copy from extended into linear memory. A pointer to a structure
; describing the request is passed in a/x.
; The function must not return anything.
;
COPYFROM:
sta ptr3
stx ptr3+1 ; Save the passed em_copy pointer
ldy #EM_COPY::OFFS
lda (ptr3),y
sta ptr1
ldy #EM_COPY::PAGE
lda (ptr3),y
clc
adc #>BASE
sta ptr1+1 ; From
ldy #EM_COPY::BUF
lda (ptr3),y
sta ptr2
iny
lda (ptr3),y
sta ptr2+1 ; To
clc ; Direction flag
common: ldy #EM_COPY::COUNT
lda (ptr3),y ; Get bytes in last page
sta ptr4
iny
lda (ptr3),y ; Get number of pages
sta ptr4+1
jmp transfer
; ------------------------------------------------------------------------
; COPYTO: Copy from linear into extended memory. A pointer to a structure
; describing the request is passed in a/x.
; The function must not return anything.
;
COPYTO: sta ptr3
stx ptr3+1 ; Save the passed em_copy pointer
ldy #EM_COPY::OFFS
lda (ptr3),y
sta ptr2
ldy #EM_COPY::PAGE
lda (ptr3),y
clc
adc #>BASE
sta ptr2+1 ; To
ldy #EM_COPY::BUF
lda (ptr3),y
sta ptr1
iny
lda (ptr3),y
sta ptr1+1 ; From
sec ; Direction flag
jmp common
|
