+++ /dev/null
-;
-; Extended memory driver for the Apple II language card
-;
-; Stefan Haubenthal, 2003-12-13
-; Ullrich von Bassewitz, 2002-12-02,2003-12-21
-;
-
- .include "zeropage.inc"
-
- .include "em-kernel.inc"
- .include "em-error.inc"
-
-
- .macpack generic
-
-
-; ------------------------------------------------------------------------
-; Header. Includes jump table
-
-.segment "JUMPTABLE"
-
-; Driver signature
-
- .byte $65, $6D, $64 ; "emd"
- .byte EMD_API_VERSION ; EM API version number
-
-; Jump table.
-
- .word INSTALL
- .word UNINSTALL
- .word PAGECOUNT
- .word MAP
- .word USE
- .word COMMIT
- .word COPYFROM
- .word COPYTO
-
-; ------------------------------------------------------------------------
-; Constants
-
-BASE = $D000 ; $Cxxx -> $Dxxx bank 1
-BASE2 = $D000
-PAGES = ($10000 - BASE) / 256
-ROMONLY2= $C082
-LC2RW = $C083
-LC1RW = $C08B
-
-; ------------------------------------------------------------------------
-; Data.
-
-.bss
-curpage: .res 1 ; Current page number
-
-.bss
-window: .res 256 ; Memory "window"
-
-.code
-
-; ------------------------------------------------------------------------
-; INSTALL routine. Is called after the driver is loaded into memory. If
-; possible, check if the hardware is present and determine the amount of
-; memory available.
-; Must return an EM_ERR_xx code in a/x.
-;
-
-INSTALL:
- lda #$FF
- sta curpage ; Invalidate the current page
- lda #EM_ERR_OK
- ldx #$00
-; rts ; Run into UNINSTALL instead
-
-; ------------------------------------------------------------------------
-; 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
-
- add #>BASE
- sta ptr1+1
- ldy #$00
- sty ptr1
-
- lda #<window
- sta ptr2
- lda #>window
- sta ptr2+1
-
-; Transfer one page
-
- jsr transfer ; Transfer one page
-
-; Return the memory window
-
- lda #<window
- ldx #>window ; Return the window address
- 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
- bmi done ; Jump if no page mapped
-
- add #>BASE
- sta ptr2+1
- ldy #$00
- sty ptr2
-
- lda #<window
- sta ptr1
- lda #>window
- sta ptr1+1
-
-; Transfer one page. Y must be zero on entry
-
-transfer:
- ldx #$00
- lda ptr2+1
- cmp #>BASE
- bcc @L1
- cmp #>BASE2
- bcs @L1
- adc #>(BASE2-BASE)
- sta ptr2+1
- ldx #LC1RW-LC2RW
-@L1: lda ptr1+1
- cmp #>BASE
- bcc @L2
- cmp #>BASE2
- bcs @L2
- adc #>(BASE2-BASE)
- sta ptr1+1
- ldx #LC1RW-LC2RW
-@L2: sei
- lda LC2RW,x ; Bank out ROMs
- lda LC2RW,x
-
-; Unroll the following loop
-
-loop: .repeat 8
- lda (ptr1),y
- sta (ptr2),y
- iny
- .endrep
-
- bne loop
-
-; Restore the old memory configuration, allow interrupts
-
- lda ROMONLY2 ; Bank in ROMs
- cli
-
-; Done
-
-done: rts
-
-; ------------------------------------------------------------------------
-; 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
- add #>BASE
- sta ptr1+1 ; From
-
- ldy #EM_COPY::BUF
- lda (ptr3),y
- sta ptr2
- iny
- lda (ptr3),y
- sta ptr2+1 ; To
-
-common: ldy #EM_COPY::COUNT+1
- lda (ptr3),y ; Get number of pages
- beq @L2 ; Skip if no full pages
- sta tmp1
-
-; Copy full pages allowing interrupts after each page copied
-
- ldy #$00
-@L1: jsr transfer
- inc ptr1+1
- inc ptr2+1
- dec tmp1
- bne @L1
-
-; Copy the remainder of the page
-
-@L2: ldy #EM_COPY::COUNT
- lda (ptr3),y ; Get bytes in last page
- beq @L4
- pha
-
- sei
- lda LC2RW,x ; Bank out ROMs
- lda LC2RW,x
- pla
- tax
-
-; Transfer the bytes in the last page
-
- ldy #$00
-@L3: lda (ptr1),y
- sta (ptr2),y
- iny
- dex
- bne @L3
-
-; Restore the old memory configuration, allow interrupts
-
- lda ROMONLY2 ; Bank in ROMs
- cli
-
-; Done
-
-@L4: rts
-
-; ------------------------------------------------------------------------
-; 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
- add #>BASE
- sta ptr2+1 ; To
-
- ldy #EM_COPY::BUF
- lda (ptr3),y
- sta ptr1
- iny
- lda (ptr3),y
- sta ptr1+1 ; From
-
- jmp common
-
-
projects / cc65 / commitdiff