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cc65/libsrc/c64/emd/c64-georam.s
Oliver Schmidt d6c3bd29ac Renamed JUMPTABLE and cleaned up module.cfg.
This change was suppsed to fix the issue that the former JUMPTABLE is merked as 'ro' while it is actually written to in several scenarios. When drivers are converted using co65 and then compiled into ROMs the JUMPTABLE isn't copied to RAM and therefore the write operations in question fail.

However unfortunately I didn't succeed in changing that :-( Just setting the former JUMPTABLE to 'rw' broke the drivers. So I placed the DATA segment directly after the former JUMPTABLE segment. This made the drivers converted with co65 work again - obviously after changing libsrc/Makefile:235 from '--code-label' to '--data-label'. But the actual dynamic drivers still didn't work as the former JUMPTABLE wasn't placed as the beginning of the loaded file anymore. That effect could be changed by exchanging src/ld65/o65.c:1391 with src/ld65/o65.c:1394 but doing so broke the drivers again :-((
2014-05-01 21:44:39 +02:00

354 lines
8.1 KiB
ArmAsm

;
; Extended memory driver for the GEORAM cartridge. Driver works without
; problems when statically linked.
;
; Ullrich von Bassewitz, 2002-11-29
;
; GEORAM page size checking routine by
; Marco van den Heuvel, 2010-01-21
;
.include "zeropage.inc"
.include "em-kernel.inc"
.include "em-error.inc"
.macpack generic
; ------------------------------------------------------------------------
; Header. Includes jump table
.segment "HEADER"
; Driver signature
.byte $65, $6d, $64 ; "emd"
.byte EMD_API_VERSION ; EM API version number
; Library reference
.addr $0000
; Jump table
.addr INSTALL
.addr UNINSTALL
.addr PAGECOUNT
.addr MAP
.addr USE
.addr COMMIT
.addr COPYFROM
.addr COPYTO
; ------------------------------------------------------------------------
; Constants
GR_WINDOW = $DE00 ; Address of GEORAM window
GR_PAGE_LO = $DFFE ; Page register low
GR_PAGE_HI = $DFFF ; Page register high
; ------------------------------------------------------------------------
; Data.
.data
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 GR_WINDOW
cpx GR_WINDOW
bne @notpresent
inc GR_WINDOW
cpx GR_WINDOW
beq @notpresent
lda #4
jsr check
cpy GR_WINDOW
beq @has64k
lda #8
jsr check
cpy GR_WINDOW
beq @has128k
lda #16
jsr check
cpy GR_WINDOW
beq @has256k
lda #32
jsr check
cpy GR_WINDOW
beq @has512k
lda #64
jsr check
cpy GR_WINDOW
beq @has1024k
lda #128
jsr check
cpy GR_WINDOW
beq @has2048k
ldx #>16384
bne @setok
@has64k:
ldx #>256
bne @setok
@has128k:
ldx #>512
bne @setok
@has256k:
ldx #>1024
bne @setok
@has512k:
ldx #>2048
bne @setok
@has1024k:
ldx #>4096
bne @setok
@has2048k:
ldx #>8192
bne @setok
@notpresent:
lda #<EM_ERR_NO_DEVICE
ldx #>EM_ERR_NO_DEVICE
rts
@setok:
lda #0
sta pagecount
stx pagecount+1
lda #<EM_ERR_OK
ldx #>EM_ERR_OK
rts
check:
ldx #0
stx GR_PAGE_LO
stx GR_PAGE_HI
ldy GR_WINDOW
iny
sta GR_PAGE_HI
sty GR_WINDOW
ldx #0
stx GR_PAGE_HI
; 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
; ------------------------------------------------------------------------
; USE: Tell the driver that the window is now associated with a given page.
; The GeoRAM cartridge does not copy but actually map the window, so USE is
; identical to MAP.
USE = MAP
; ------------------------------------------------------------------------
; 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 tmp1
txa
asl tmp1
rol a
asl tmp1
rol a
sta GR_PAGE_HI
lda tmp1
lsr a
lsr a
sta GR_PAGE_LO
lda #<GR_WINDOW
ldx #>GR_WINDOW
; Use the RTS from COMMIT below to save a precious byte of storage
; ------------------------------------------------------------------------
; COMMIT: Commit changes in the memory window to extended storage.
COMMIT: 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 is:
;
; - ptr1 contains the struct pointer
; - ptr2 contains the linear memory buffer
; - ptr3 contains -(count-1)
; - tmp1 contains the low page register value
; - tmp2 contains the high page register value
; - X contains the page offset
; - Y contains zero
jmp @L5
@L1: lda GR_WINDOW,x
sta (ptr2),y
iny
bne @L2
inc ptr2+1
@L2: inx
beq @L4
; Bump count and repeat
@L3: inc ptr3
bne @L1
inc ptr3+1
bne @L1
rts
; Bump page register
@L4: inc tmp1 ; Bump low page register
bit tmp1 ; Check for overflow in bit 6
bvc @L6 ; Jump if no overflow
inc tmp2
@L5: lda tmp2
sta GR_PAGE_HI
@L6: lda tmp1
sta GR_PAGE_LO
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:
jsr setup
; Setup is:
;
; - ptr1 contains the struct pointer
; - ptr2 contains the linear memory buffer
; - ptr3 contains -(count-1)
; - tmp1 contains the low page register value
; - tmp2 contains the high page register value
; - X contains the page offset
; - Y contains zero
jmp @L5
@L1: lda (ptr2),y
sta GR_WINDOW,x
iny
bne @L2
inc ptr2+1
@L2: inx
beq @L4
; Bump count and repeat
@L3: inc ptr3
bne @L1
inc ptr3+1
bne @L1
rts
; Bump page register
@L4: inc tmp1 ; Bump low page register
bit tmp1 ; Check for overflow in bit 6
bvc @L6 ; Jump if no overflow
inc tmp2
@L5: lda tmp2
sta GR_PAGE_HI
@L6: lda tmp1
sta GR_PAGE_LO
jmp @L3
; ------------------------------------------------------------------------
; 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: lower 6 bits in tmp1, high bits in tmp2.
ldy #EM_COPY::PAGE+1
lda (ptr1),y
sta tmp2
dey
lda (ptr1),y
asl a
rol tmp2
asl a
rol tmp2
lsr a
lsr a
sta 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 X and clear Y
ldy #EM_COPY::OFFS
lda (ptr1),y
tax
ldy #$00
; Done
rts