mirror of
https://github.com/cc65/cc65.git
synced 2024-12-28 06:30:16 +00:00
270 lines
6.6 KiB
ArmAsm
270 lines
6.6 KiB
ArmAsm
;
|
|
; Extended memory driver for the C16 hidden RAM. Driver works without
|
|
; problems when statically linked.
|
|
;
|
|
; Ullrich von Bassewitz, 2003-12-15
|
|
;
|
|
|
|
.include "zeropage.inc"
|
|
|
|
.include "em-kernel.inc"
|
|
.include "em-error.inc"
|
|
.include "../plus4/plus4.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 = $8000
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Data.
|
|
|
|
.bss
|
|
pages: .res 1 ; Number of pages
|
|
curpage: .res 1 ; Current page number
|
|
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:
|
|
|
|
; Determine how much memory is available. We will use all memory above
|
|
; $8000 up to MEMTOP
|
|
|
|
sec
|
|
jsr $FF99 ; MEMTOP: Get top memory into Y/X
|
|
tya
|
|
sub #>BASE ; Low 32 K are used
|
|
bcc nomem
|
|
beq nomem ; Offering zero pages is a bad idea
|
|
sta pages
|
|
|
|
ldx #$FF
|
|
stx curpage ; Invalidate the current page
|
|
inx ; X = 0
|
|
txa ; A = X = EM_ERR_OK
|
|
rts
|
|
|
|
nomem: ldx #>EM_ERR_NO_DEVICE
|
|
lda #<EM_ERR_NO_DEVICE
|
|
; 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 #$00 ; 128 pages max
|
|
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. Because we bank out the
|
|
; kernal, we will run the routine with interrupts disabled but leave
|
|
; short breath times. Unroll the following loop to make it somewhat faster.
|
|
|
|
transfer:
|
|
sei
|
|
sta ENABLE_RAM
|
|
|
|
.repeat 8
|
|
lda (ptr1),y
|
|
sta (ptr2),y
|
|
iny
|
|
.endrepeat
|
|
|
|
sta ENABLE_ROM
|
|
cli
|
|
|
|
bne transfer
|
|
|
|
; 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
|
|
tax
|
|
|
|
sei ; Disable ints
|
|
sta ENABLE_RAM ; Bank out the ROM
|
|
|
|
; 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
|
|
|
|
sta ENABLE_ROM
|
|
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
|
|
|
|
|