;
-; Extended memory driver for the C128 RAM in bank #1. Driver works without
+; 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"
; Constants
BASE = $400
-TOPMEM = $FF00
-PAGES = (TOPMEM - BASE) / 256
; ------------------------------------------------------------------------
; Data.
.bss
-curpage: .res 1 ; Current page number
+curpage: .res 2 ; Current page number
+curbank: .res 1 ; Current bank number
+copybank: .res 2 ; temp bank number
window: .res 256 ; Memory "window"
+pagecount: .res 2 ; Number of available pages
+
.code
; ------------------------------------------------------------------------
;
INSTALL:
+ ldx #0
+ stx ptr1
+ ldx #4
+ stx ptr1+1
+ ldx #<ptr1
+ stx FETVEC
+ stx STAVEC
+ ldy #0
+ ldx #MMU_CFG_RAM1
+ jsr FETCH
+ sta tmp1
+ ldx #MMU_CFG_RAM3
+ jsr FETCH
+ cmp tmp1
+ bne @has_4_banks
+ tax
+ inx
+ txa
+ ldx #MMU_CFG_RAM1
+ jsr STASH
+ ldx #MMU_CFG_RAM3
+ jsr FETCH
+ cmp tmp1
+ beq @has_4_banks
+ ldx #0
+ lda #251
+ bne @setok
+
+@has_4_banks:
+ ldx #2
+ lda #241
+@setok:
+ sta pagecount
+ stx pagecount+1
ldx #$FF
stx curpage
- stx curpage+1 ; Invalidate the current page
- inx
- txa ; A = X = EM_ERR_OK
- rts
+ 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.
;
PAGECOUNT:
- lda #<PAGES
- ldx #>PAGES
+ lda pagecount
+ ldx pagecount+1
rts
; ------------------------------------------------------------------------
; by the driver.
;
-MAP: sta curpage
+MAP: sei
+ sta curpage
stx curpage+1 ; Remember the new page
- clc
- adc #>BASE
- sta ptr1+1
- ldy #$00
- sty ptr1
+ 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 #MMU_CFG_RAM1
+@L1: ldx curbank
+ jsr getcurbankmmu
jsr FETCH
sta window,y
iny
lda #<window
ldx #>window ; Return the window address
+ cli
rts
; ------------------------------------------------------------------------
; ------------------------------------------------------------------------
; COMMIT: Commit changes in the memory window to extended storage.
-COMMIT: lda curpage ; Get the current page
+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
+ sty ptr1
lda #<ptr1
sta STAVEC
; Transfer one page. Y must be zero on entry
@L1: lda window,y
- ldx #MMU_CFG_RAM1
+ ldx curbank
+ jsr getcurbankmmu
jsr STASH
iny
bne @L1
+ cli
; Done
;
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
+ sei
+ jsr setup
- lda #<ptr1
+; 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
- 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
+@L1: ldx tmp1
+ jsr getcurbankmmu
+ ldy #0
jsr FETCH
+ ldy tmp2
sta (ptr2),y
- iny
- bne @L1
- inc ptr1+1
+ inc tmp2
+ bne @L2
inc ptr2+1
- dec tmp1
- bne @L1
+@L2: inc ptr4
+ beq @L4
-; Copy the remainder of the page
+; Bump count and repeat
-@L2: ldy #EM_COPY::COUNT
- lda (ptr3),y ; Get bytes in last page
- beq @L4
- sta tmp1
+@L3: inc ptr3
+ bne @L1
+ inc ptr3+1
+ bne @L1
+ cli
+ rts
- ldy #$00
-@L3: ldx #MMU_CFG_RAM1
- jsr FETCH
- sta (ptr2),y
- iny
- dec tmp1
- bne @L3
+; Bump page register
-; Done
+@L4: inc ptr4+1
+ lda ptr4+1
+ cmp #$ff
+ bne @L3
+ lda #4
+ sta ptr4+1
+ inc tmp1
+@L5:
+ jmp @L3
-@L4: rts
; ------------------------------------------------------------------------
; COPYTO: Copy from linear into extended memory. A pointer to a structure
; The function must not return anything.
;
-COPYTO: sta ptr3
- stx ptr3+1 ; Save the passed em_copy pointer
+COPYTO:
+ sei
+ jsr setup
- 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
+; 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
- ldy #EM_COPY::COUNT+1
- lda (ptr3),y ; Get number of pages
- beq @L2 ; Skip if no full pages
- sta tmp1
-
-; Copy full pages
+; Bump count and repeat
- ldy #$00
-@L1: lda (ptr2),y
- ldx #MMU_CFG_RAM1
- jsr STASH
- iny
+@L3: inc ptr3
bne @L1
- inc ptr1+1
- inc ptr2+1
- dec tmp1
+ inc ptr3+1
bne @L1
+ cli
+ rts
-; Copy the remainder of the page
+; Bump page register
-@L2: ldy #EM_COPY::COUNT
- lda (ptr3),y ; Get bytes in last page
- beq @L4
- sta tmp1
+@L4: inc ptr4+1
+ lda ptr4+1
+ cmp #$ff
+ bne @L3
+ inc tmp1
+ lda #4
+ sta ptr4+1
+@L5:
+ jmp @L3
- ldy #$00
-@L3: lda (ptr2),y
+; ------------------------------------------------------------------------
+; Helper function to calculate the correct bank and page
+; when addressing bank 2 or 3
+
+calculate_bank_and_correct_page:
+ cpx #2
+ beq @calculate_bank_3_with_2
+ cpx #1
+ beq @calculate_bank_2_or_3_with_1
+ sec
+ sbc #251
+ bcs @calculate_bank_2_with_0
+ ldx #1
+ lda curpage
+ rts
+
+@calculate_bank_3_with_2:
+ lda curpage
+ clc
+ adc #10
+@calculate_bank_3_with_1:
+ ldx #3
+ rts
+
+@calculate_bank_2_or_3_with_1:
+ sec
+ sbc #246
+ bcs @calculate_bank_3_with_1
+ lda curpage
+ clc
+ adc #5
+@calculate_bank_2_with_0:
+ ldx #2
+ rts
+
+; ------------------------------------------------------------------------
+; Helper function to get the correct mmu value in x
+
+getcurbankmmu:
+ cpx #1
+ beq @bank1
+ cpx #2
+ beq @bank2
+ ldx #MMU_CFG_RAM3
+ rts
+@bank2:
+ ldx #MMU_CFG_RAM2
+ rts
+@bank1:
ldx #MMU_CFG_RAM1
- jsr STASH
+ rts
+
+; ------------------------------------------------------------------------
+; Helper function for COPYFROM and COPYTO: Store the pointer to the request
+; structure and prepare data for the copy
+
+setup: sta ptr1
+ stx ptr1+1 ; Save passed pointer
+
+; Get the page number from the struct and adjust it so that it may be used
+; with the hardware. That is: page pointer in ptr4 and bank in tmp1
+
+ ldy #EM_COPY::PAGE+1
+ lda (ptr1),y
+ tax
+ dey
+ lda (ptr1),y
+ sta curpage
+ jsr calculate_bank_and_correct_page
+ clc
+ adc #4
+ sta ptr4+1
+ stx tmp1
+
+; Get the buffer pointer into ptr2
+
+ ldy #EM_COPY::BUF
+ lda (ptr1),y
+ sta ptr2
iny
- dec tmp1
- bne @L3
+ lda (ptr1),y
+ sta ptr2+1
-; Done
+; Get the count, calculate -(count-1) and store it into ptr3
-@L4: rts
+ ldy #EM_COPY::COUNT
+ lda (ptr1),y
+ eor #$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
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