mirror of
https://github.com/cc65/cc65.git
synced 2024-08-30 16:29:06 +00:00
Machines with RAM in pages 2+3 are quite rare, so it's better to have the additional code+features in a separate driver. git-svn-id: svn://svn.cc65.org/cc65/trunk@4575 b7a2c559-68d2-44c3-8de9-860c34a00d81
427 lines
9.6 KiB
ArmAsm
427 lines
9.6 KiB
ArmAsm
;
|
|
; Extended memory driver for the C128 RAM in banks #1, #2 and #3. Driver works without
|
|
; problems when statically linked.
|
|
;
|
|
; Ullrich von Bassewitz, 2002-12-04
|
|
;
|
|
; Updated to use banks 2 and 3 as well by
|
|
; Marco van den Heuvel, 2010-01-21
|
|
;
|
|
|
|
.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 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 = $400
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Data.
|
|
|
|
.bss
|
|
curpage: .res 2 ; Current page number
|
|
curbank: .res 1 ; Current bank number
|
|
copybank: .res 2 ; temp bank number
|
|
|
|
window: .res 256 ; Memory "window"
|
|
|
|
pagecount: .res 2 ; Number of available pages
|
|
|
|
.code
|
|
|
|
; ------------------------------------------------------------------------
|
|
; INSTALL routine. Is called after the driver is loaded into memory. If
|
|
; possible, check if the hardware is present and determine the amount of
|
|
; memory available.
|
|
; Must return an EM_ERR_xx code in a/x.
|
|
;
|
|
|
|
INSTALL:
|
|
ldx #0
|
|
stx ptr1
|
|
ldx #4
|
|
stx ptr1+1
|
|
ldx #<ptr1
|
|
stx FETVEC
|
|
stx STAVEC
|
|
ldy #0
|
|
ldx #MMU_CFG_RAM1
|
|
jsr FETCH
|
|
sta tmp1
|
|
ldx #MMU_CFG_RAM3
|
|
jsr FETCH
|
|
cmp tmp1
|
|
bne @has_4_banks
|
|
tax
|
|
inx
|
|
txa
|
|
ldx #MMU_CFG_RAM1
|
|
jsr STASH
|
|
ldx #MMU_CFG_RAM3
|
|
jsr FETCH
|
|
cmp tmp1
|
|
beq @has_4_banks
|
|
ldx #0
|
|
lda #251
|
|
bne @setok
|
|
|
|
@has_4_banks:
|
|
ldx #2
|
|
lda #241
|
|
@setok:
|
|
sta pagecount
|
|
stx pagecount+1
|
|
ldx #$FF
|
|
stx curpage
|
|
stx curpage+1 ; Invalidate the current page
|
|
inx
|
|
txa ; A = X = EM_ERR_OK
|
|
; 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 pagecount
|
|
ldx pagecount+1
|
|
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: sei
|
|
sta curpage
|
|
stx curpage+1 ; Remember the new page
|
|
|
|
jsr calculate_bank_and_correct_page
|
|
stx curbank
|
|
|
|
clc
|
|
adc #>BASE
|
|
sta ptr1+1
|
|
ldy #$00
|
|
sty ptr1
|
|
lda #<ptr1
|
|
sta FETVEC
|
|
|
|
; Transfer one page
|
|
|
|
@L1: ldx curbank
|
|
jsr getcurbankmmu
|
|
jsr FETCH
|
|
sta window,y
|
|
iny
|
|
bne @L1
|
|
|
|
; Return the memory window
|
|
|
|
lda #<window
|
|
ldx #>window ; Return the window address
|
|
cli
|
|
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: sei
|
|
lda curpage ; Get the current page
|
|
ldx curpage+1
|
|
bmi done ; Jump if no page mapped
|
|
|
|
jsr calculate_bank_and_correct_page
|
|
stx curbank
|
|
|
|
clc
|
|
adc #>BASE
|
|
sta ptr1+1
|
|
ldy #$00
|
|
sty ptr1
|
|
|
|
lda #<ptr1
|
|
sta STAVEC
|
|
|
|
; Transfer one page. Y must be zero on entry
|
|
|
|
@L1: lda window,y
|
|
ldx curbank
|
|
jsr getcurbankmmu
|
|
jsr STASH
|
|
iny
|
|
bne @L1
|
|
cli
|
|
|
|
; Done
|
|
|
|
done: rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; COPYFROM: Copy from extended into linear memory. A pointer to a structure
|
|
; describing the request is passed in a/x.
|
|
; The function must not return anything.
|
|
;
|
|
|
|
COPYFROM:
|
|
sei
|
|
jsr setup
|
|
|
|
; Setup is:
|
|
;
|
|
; - ptr1 contains the struct pointer
|
|
; - ptr2 contains the linear memory buffer
|
|
; - ptr3 contains -(count-1)
|
|
; - ptr4 contains the page buffer and offset
|
|
; - tmp1 contains the bank
|
|
; - tmp2 contains zero (used for linear memory buffer offset)
|
|
|
|
lda #<ptr4
|
|
sta FETVEC
|
|
jmp @L3
|
|
|
|
@L1: ldx tmp1
|
|
jsr getcurbankmmu
|
|
ldy #0
|
|
jsr FETCH
|
|
ldy tmp2
|
|
sta (ptr2),y
|
|
inc tmp2
|
|
bne @L2
|
|
inc ptr2+1
|
|
@L2: inc ptr4
|
|
beq @L4
|
|
|
|
; Bump count and repeat
|
|
|
|
@L3: inc ptr3
|
|
bne @L1
|
|
inc ptr3+1
|
|
bne @L1
|
|
cli
|
|
rts
|
|
|
|
; Bump page register
|
|
|
|
@L4: inc ptr4+1
|
|
lda ptr4+1
|
|
cmp #$ff
|
|
bne @L3
|
|
lda #4
|
|
sta ptr4+1
|
|
inc tmp1
|
|
@L5:
|
|
jmp @L3
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
; 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:
|
|
sei
|
|
jsr setup
|
|
|
|
; Setup is:
|
|
;
|
|
; - ptr1 contains the struct pointer
|
|
; - ptr2 contains the linear memory buffer
|
|
; - ptr3 contains -(count-1)
|
|
; - ptr4 contains the page buffer and offset
|
|
; - tmp1 contains the bank
|
|
; - tmp2 contains zero (used for linear memory buffer offset)
|
|
|
|
lda #<ptr4
|
|
sta STAVEC
|
|
jmp @L3
|
|
|
|
@L1:
|
|
ldy tmp2
|
|
lda (ptr2),y
|
|
ldx tmp1
|
|
jsr getcurbankmmu
|
|
ldy #0
|
|
jsr STASH
|
|
inc tmp2
|
|
bne @L2
|
|
inc ptr2+1
|
|
@L2: inc ptr4
|
|
beq @L4
|
|
|
|
; Bump count and repeat
|
|
|
|
@L3: inc ptr3
|
|
bne @L1
|
|
inc ptr3+1
|
|
bne @L1
|
|
cli
|
|
rts
|
|
|
|
; Bump page register
|
|
|
|
@L4: inc ptr4+1
|
|
lda ptr4+1
|
|
cmp #$ff
|
|
bne @L3
|
|
inc tmp1
|
|
lda #4
|
|
sta ptr4+1
|
|
@L5:
|
|
jmp @L3
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Helper function to calculate the correct bank and page
|
|
; when addressing bank 2 or 3
|
|
|
|
calculate_bank_and_correct_page:
|
|
cpx #2
|
|
beq @calculate_bank_3_with_2
|
|
cpx #1
|
|
beq @calculate_bank_2_or_3_with_1
|
|
sec
|
|
sbc #251
|
|
bcs @calculate_bank_2_with_0
|
|
ldx #1
|
|
lda curpage
|
|
rts
|
|
|
|
@calculate_bank_3_with_2:
|
|
lda curpage
|
|
clc
|
|
adc #10
|
|
@calculate_bank_3_with_1:
|
|
ldx #3
|
|
rts
|
|
|
|
@calculate_bank_2_or_3_with_1:
|
|
sec
|
|
sbc #246
|
|
bcs @calculate_bank_3_with_1
|
|
lda curpage
|
|
clc
|
|
adc #5
|
|
@calculate_bank_2_with_0:
|
|
ldx #2
|
|
rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Helper function to get the correct mmu value in x
|
|
|
|
getcurbankmmu:
|
|
cpx #1
|
|
beq @bank1
|
|
cpx #2
|
|
beq @bank2
|
|
ldx #MMU_CFG_RAM3
|
|
rts
|
|
@bank2:
|
|
ldx #MMU_CFG_RAM2
|
|
rts
|
|
@bank1:
|
|
ldx #MMU_CFG_RAM1
|
|
rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Helper function for COPYFROM and COPYTO: Store the pointer to the request
|
|
; structure and prepare data for the copy
|
|
|
|
setup: sta ptr1
|
|
stx ptr1+1 ; Save passed pointer
|
|
|
|
; Get the page number from the struct and adjust it so that it may be used
|
|
; with the hardware. That is: page pointer in ptr4 and bank in tmp1
|
|
|
|
ldy #EM_COPY::PAGE+1
|
|
lda (ptr1),y
|
|
tax
|
|
dey
|
|
lda (ptr1),y
|
|
sta curpage
|
|
jsr calculate_bank_and_correct_page
|
|
clc
|
|
adc #4
|
|
sta ptr4+1
|
|
stx tmp1
|
|
|
|
; Get the buffer pointer into ptr2
|
|
|
|
ldy #EM_COPY::BUF
|
|
lda (ptr1),y
|
|
sta ptr2
|
|
iny
|
|
lda (ptr1),y
|
|
sta ptr2+1
|
|
|
|
; Get the count, calculate -(count-1) and store it into ptr3
|
|
|
|
ldy #EM_COPY::COUNT
|
|
lda (ptr1),y
|
|
eor #$FF
|
|
sta ptr3
|
|
iny
|
|
lda (ptr1),y
|
|
eor #$FF
|
|
sta ptr3+1
|
|
|
|
; Get the page offset into the low byte of ptr4 clear tmp2
|
|
|
|
ldy #EM_COPY::OFFS
|
|
lda (ptr1),y
|
|
sta ptr4
|
|
lda #0
|
|
sta tmp2
|
|
|
|
; Done
|
|
|
|
rts
|