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cc65/libsrc/c128/c128-ram.s
cuz fb8984c73b Fixed a bug
git-svn-id: svn://svn.cc65.org/cc65/trunk@1725 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-12-06 21:54:49 +00:00

286 lines
6.5 KiB
ArmAsm

;
; Extended memory driver for the C128 RAM in bank #1
;
; Ullrich von Bassewitz, 2002-12-04
;
.include "zeropage.inc"
.include "em-kernel.inc"
.include "em-error.inc"
.include "c128.inc"
.macpack generic
; ------------------------------------------------------------------------
; Header. Includes jump table
.segment "JUMPTABLE"
; Driver signature
.byte $65, $6d, $64 ; "emd"
.byte $00 ; EM API version number
; Jump table.
.word INSTALL
.word DEINSTALL
.word PAGECOUNT
.word MAP
.word USE
.word COMMIT
.word COPYFROM
.word COPYTO
; ------------------------------------------------------------------------
; Constants
BASE = $400
TOPMEM = $FF00
PAGES = (TOPMEM - BASE) / 256
; ------------------------------------------------------------------------
; Data.
.data
curpage: .word $FFFF ; 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:
lda #<EM_ERR_OK
ldx #>EM_ERR_OK
rts
; ------------------------------------------------------------------------
; DEINSTALL routine. Is called before the driver is removed from memory.
; Can do cleanup or whatever. Must not return anything.
;
DEINSTALL:
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
stx curpage+1 ; Remember the new page
clc
adc #>BASE
sta ptr1+1
ldy #$00
sty ptr1
lda #<ptr1
sta FETVEC
; Transfer one page
@L1: ldx #MMU_CFG_RAM1
jsr FETCH
sta window,y
iny
bne @L1
; 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
stx curpage+1 ; 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
ldx curpage+1
bmi done ; Jump if no page mapped
clc
adc #>BASE
sta ptr1+1
ldy #$00
sty ptr1
lda #<ptr1
sta STAVEC
; Transfer one page. Y must be zero on entry
@L1: lda window,y
ldx #MMU_CFG_RAM1
jsr STASH
iny
bne @L1
; 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
clc
adc #>BASE
sta ptr1+1 ; From
ldy #EM_COPY_BUF
lda (ptr3),y
sta ptr2
iny
lda (ptr3),y
sta ptr2+1 ; To
lda #<ptr1
sta FETVEC
ldy #EM_COPY_COUNT+1
lda (ptr3),y ; Get number of pages
beq @L2 ; Skip if no full pages
sta tmp1
; Copy full pages
ldy #$00
@L1: ldx #MMU_CFG_RAM1
jsr FETCH
sta (ptr2),y
iny
bne @L1
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
sta tmp1
ldy #$00
@L3: ldx #MMU_CFG_RAM1
jsr FETCH
sta (ptr2),y
iny
dec tmp1
bne @L3
; 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 ptr1
ldy #EM_COPY_PAGE
lda (ptr3),y
clc
adc #>BASE
sta ptr1+1 ; To
ldy #EM_COPY_BUF
lda (ptr3),y
sta ptr2
iny
lda (ptr3),y
sta ptr2+1 ; From
lda #<ptr1
sta STAVEC
ldy #EM_COPY_COUNT+1
lda (ptr3),y ; Get number of pages
beq @L2 ; Skip if no full pages
sta tmp1
; Copy full pages
ldy #$00
@L1: lda (ptr2),y
ldx #MMU_CFG_RAM1
jsr STASH
iny
bne @L1
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
sta tmp1
ldy #$00
@L3: lda (ptr2),y
ldx #MMU_CFG_RAM1
jsr STASH
iny
dec tmp1
bne @L3
; Done
@L4: rts