mirror of
https://github.com/cc65/cc65.git
synced 2024-12-26 08:32:00 +00:00
a7042ddbe4
Use wrappers to call the kernal in bank 15 instead of implementing kernal functionality within the cc65 libs (eats performance but is much smaller and simpler). Improved startup/shutdown code allows a return to the system bank without calling the BASIC cold start vector. git-svn-id: svn://svn.cc65.org/cc65/trunk@2793 b7a2c559-68d2-44c3-8de9-860c34a00d81
324 lines
6.9 KiB
ArmAsm
324 lines
6.9 KiB
ArmAsm
;
|
|
; Extended memory driver for the CBM610 additional RAM banks. Driver works
|
|
; without problems when linked statically.
|
|
;
|
|
; Ullrich von Bassewitz, 2002-12-09, 2003-12-20
|
|
;
|
|
|
|
.include "zeropage.inc"
|
|
|
|
.include "em-kernel.inc"
|
|
.include "em-error.inc"
|
|
.include "cbm610.inc"
|
|
|
|
.macpack generic
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Header. Includes jump table
|
|
|
|
.segment "JUMPTABLE"
|
|
|
|
; Driver signature
|
|
|
|
.byte $65, $6d, $64 ; "emd"
|
|
.byte EMD_API_VERSION ; EM API version number
|
|
|
|
; Jump table.
|
|
|
|
.word INSTALL
|
|
.word UNINSTALL
|
|
.word PAGECOUNT
|
|
.word MAP
|
|
.word USE
|
|
.word COMMIT
|
|
.word COPYFROM
|
|
.word COPYTO
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Constants
|
|
|
|
RAMBANK = 2
|
|
OFFS = 2
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Data.
|
|
|
|
.bss
|
|
curpage: .res 1 ; Current page number
|
|
|
|
window: .res 256 ; Memory "window"
|
|
pagecount: .res 1 ; Number of available pages
|
|
|
|
|
|
.code
|
|
|
|
; ------------------------------------------------------------------------
|
|
; INSTALL routine. Is called after the driver is loaded into memory. If
|
|
; possible, check if the hardware is present and determine the amount of
|
|
; memory available.
|
|
; Must return an EM_ERR_xx code in a/x.
|
|
;
|
|
|
|
INSTALL:
|
|
lda #$FF
|
|
sta curpage ; Invalidate the current page
|
|
sta pagecount ; Assume all memory available
|
|
|
|
sec
|
|
jsr $FF99 ; MEMTOP
|
|
|
|
cmp #RAMBANK ; Top of memory in bank 2?
|
|
bne @L1 ; No: We can use all the memory
|
|
txa
|
|
sub #OFFS
|
|
tya
|
|
sbc #$00
|
|
sta pagecount
|
|
|
|
@L1: lda #<EM_ERR_OK
|
|
ldx #>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 #0
|
|
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
|
|
|
|
sta ptr1+1
|
|
lda #OFFS
|
|
sta ptr1
|
|
|
|
; Transfer one page
|
|
|
|
ldx IndReg
|
|
lda #RAMBANK
|
|
sta IndReg
|
|
|
|
ldy #$00
|
|
@L1: .repeat 2
|
|
lda (ptr1),y
|
|
sta window,y
|
|
iny
|
|
.endrepeat
|
|
bne @L1
|
|
|
|
stx IndReg
|
|
|
|
; Return the memory window
|
|
|
|
lda #<window
|
|
ldx #>window ; Return the window address
|
|
rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; USE: Tell the driver that the window is now associated with a given page.
|
|
|
|
USE: sta curpage ; Remember the page
|
|
lda #<window
|
|
ldx #>window ; Return the window
|
|
rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; COMMIT: Commit changes in the memory window to extended storage.
|
|
|
|
COMMIT: lda curpage ; Get the current page
|
|
cmp #$FF
|
|
beq done ; Jump if no page mapped
|
|
|
|
sta ptr1+1
|
|
lda #OFFS
|
|
sta ptr1
|
|
|
|
; Transfer one page
|
|
|
|
ldx IndReg
|
|
lda #RAMBANK
|
|
sta IndReg
|
|
|
|
ldy #$00
|
|
@L1: .repeat 2
|
|
lda window,y
|
|
sta (ptr1),y
|
|
iny
|
|
.endrepeat
|
|
bne @L1
|
|
|
|
stx IndReg
|
|
|
|
; 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:
|
|
jsr setup
|
|
|
|
; Setup the buffer address in this bank.
|
|
|
|
sta copyfrom_buf
|
|
stx copyfrom_buf+1
|
|
|
|
; Check if we must copy full pages
|
|
|
|
ldx ptr2+1
|
|
beq @L2
|
|
|
|
; Copy full pages
|
|
|
|
ldx #$00
|
|
@L1: jsr copyfrom
|
|
inc ptr1+1
|
|
inc copyfrom_buf+1
|
|
@L2: dec ptr2+1
|
|
bne @L1
|
|
|
|
; Copy the remaining page
|
|
|
|
ldx ptr2
|
|
beq @L3
|
|
|
|
jsr copyfrom
|
|
|
|
; Restore the indirect segment
|
|
|
|
@L3: lda ExecReg
|
|
sta IndReg
|
|
|
|
; Done
|
|
|
|
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: jsr setup
|
|
|
|
; Setup the buffer address in this bank.
|
|
|
|
sta copyto_buf
|
|
stx copyto_buf+1
|
|
|
|
; Check if we must copy full pages
|
|
|
|
ldx ptr2+1
|
|
beq @L2
|
|
|
|
; Copy full pages
|
|
|
|
ldx #$00
|
|
@L1: jsr copyto
|
|
inc ptr1+1
|
|
inc copyto_buf+1
|
|
@L2: dec ptr2+1
|
|
bne @L1
|
|
|
|
; Copy the remaining page
|
|
|
|
ldx ptr2
|
|
beq @L3
|
|
|
|
jsr copyto
|
|
|
|
; Restore the indirect segment
|
|
|
|
@L3: lda ExecReg
|
|
sta IndReg
|
|
|
|
; Done
|
|
|
|
rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; setup: Helper function for COPYFROM and COPYTO, will setup parameters.
|
|
;
|
|
|
|
setup: sta ptr3
|
|
stx ptr3+1 ; Save the passed em_copy pointer
|
|
|
|
ldy #EM_COPY::OFFS
|
|
lda (ptr3),y
|
|
add #OFFS
|
|
sta ptr1
|
|
ldy #EM_COPY::PAGE
|
|
lda (ptr3),y
|
|
adc #$00
|
|
sta ptr1+1
|
|
|
|
ldy #EM_COPY::COUNT
|
|
lda (ptr3),y
|
|
sta ptr2
|
|
iny
|
|
lda (ptr3),y
|
|
sta ptr2+1 ; Get count into ptr2
|
|
|
|
ldy #EM_COPY::BUF+1
|
|
lda (ptr3),y
|
|
tax
|
|
dey
|
|
lda (ptr3),y ; Get the buffer pointer into a/x
|
|
|
|
ldy #RAMBANK
|
|
sty IndReg
|
|
|
|
ldy #$00
|
|
|
|
rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; copyfrom
|
|
|
|
.data
|
|
copyfrom:
|
|
lda (ptr1),y
|
|
copyfrom_buf = * + 1
|
|
sta $0000,y
|
|
iny
|
|
dex
|
|
bne copyfrom
|
|
rts
|
|
|
|
; ------------------------------------------------------------------------
|
|
; copyto
|
|
|
|
.data
|
|
copyto:
|
|
copyto_buf = * + 1
|
|
lda $0000,y
|
|
sta (ptr1),y
|
|
iny
|
|
dex
|
|
bne copyto
|
|
rts
|
|
|