d6c3bd29ac
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 :-((
249 lines
6.7 KiB
ArmAsm
249 lines
6.7 KiB
ArmAsm
;
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; Extended memory driver for the C64 D2TV (the second or PAL version).
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; Driver works without problems when statically linked.
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;
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; Ullrich von Bassewitz, 2005-11-27
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;
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.include "zeropage.inc"
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.include "em-kernel.inc"
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.include "em-error.inc"
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.import _get_ostype
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.macpack generic
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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.segment "HEADER"
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; Driver signature
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.byte $65, $6d, $64 ; "emd"
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.byte EMD_API_VERSION ; EM API version number
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; Library reference
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.addr $0000
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; Jump table
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.addr INSTALL
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.addr UNINSTALL
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.addr PAGECOUNT
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.addr MAP
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.addr USE
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.addr COMMIT
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.addr COPYFROM
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.addr COPYTO
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; ------------------------------------------------------------------------
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; Constants
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OP_COPYFROM = %00001101
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OP_COPYTO = %00001111
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START_BANK = 2 ; Start at $20000
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PAGES = (2048 - 128) * 4
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; ------------------------------------------------------------------------
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; Data.
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.bss
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window: .res 256 ; Memory "window"
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.data
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; The MAP and COMMIT entries will actually call COPYFROM/COPYTO with
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; a pointer to the following data structure:
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dma_params: .word window ; Host address
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.byte 0 ; Offset in page
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curpage: .word $0000 ; Page
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.word .sizeof (window); # bytes to move, lo, hi
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.code
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; ------------------------------------------------------------------------
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; INSTALL routine. Is called after the driver is loaded into memory. If
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; possible, check if the hardware is present and determine the amount of
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; memory available.
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; Must return an EM_ERR_xx code in a/x.
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;
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INSTALL:
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; Check for a DTV
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ldx #1
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stx $d03f
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ldx $d040
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cpx $d000
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bne @present
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inc $d000
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cpx $d040
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beq @present
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dec $d000
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; DTV not found
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lda #<EM_ERR_NO_DEVICE
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ldx #>EM_ERR_NO_DEVICE
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rts
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@present:
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ldx #$FF
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stx curpage+1 ; Invalidate curpage
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inx ; X = 0
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txa ; A/X = EM_ERR_OK
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; rts ; Run into UNINSTALL instead
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; ------------------------------------------------------------------------
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; UNINSTALL routine. Is called before the driver is removed from memory.
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; Can do cleanup or whatever. Must not return anything.
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;
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UNINSTALL:
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rts
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; ------------------------------------------------------------------------
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; PAGECOUNT: Return the total number of available pages in a/x.
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;
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PAGECOUNT:
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lda #<PAGES
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ldx #>PAGES
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rts
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; ------------------------------------------------------------------------
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; MAP: Map the page in a/x into memory and return a pointer to the page in
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; a/x. The contents of the currently mapped page (if any) may be discarded
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; by the driver.
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;
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MAP: sta curpage
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stx curpage+1 ; Remember the new page
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lda #<dma_params
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ldx #>dma_params
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jsr COPYFROM ; Copy data into the window
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lda #<window
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ldx #>window ; Return the window address
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done: rts
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; ------------------------------------------------------------------------
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; USE: Tell the driver that the window is now associated with a given page.
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USE: sta curpage
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stx curpage+1 ; Remember the page
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lda #<window
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ldx #>window ; Return the window
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rts
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; ------------------------------------------------------------------------
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; COMMIT: Commit changes in the memory window to extended storage.
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COMMIT: lda curpage+1 ; Do we have a page mapped?
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bmi done ; Jump if no page mapped
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lda #<dma_params
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ldx #>dma_params
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; Run into COPYTO
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; ------------------------------------------------------------------------
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; COPYTO: Copy from linear into extended memory. A pointer to a structure
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; describing the request is passed in a/x.
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; The function must not return anything.
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;
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COPYTO: sta ptr1
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stx ptr1+1 ; Save the pointer
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ldx #OP_COPYTO ; Load the command
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bne transfer
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; ------------------------------------------------------------------------
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; COPYFROM: Copy from extended into linear memory. A pointer to a structure
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; describing the request is passed in a/x.
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; The function must not return anything.
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;
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COPYFROM:
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sta ptr1
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stx ptr1+1 ; Save the pointer
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ldx #OP_COPYFROM
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; DTV DMA transfer routine. Expects the command in X.
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; NOTE: We're using knowledge about field order in the EM_COPY struct here!
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transfer:
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jsr WAIT ; Wait until DMA is finished
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; Modulo disable
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ldy #$00
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sty $d31e
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; Setup the target address and the source and target steps. Y contains zero,
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; which is EM_COPY::BUF.
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sty $d307 ; Source step high = 0
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sty $d309 ; Dest step high = 0
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lda (ptr1),y
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sta $d303 ; Dest address low
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iny ; Y = 1
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sty $d306 ; Source step low = 1
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sty $d308 ; Dest step low = 1
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lda (ptr1),y
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sta $d304
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lda #$40 ; Dest is always RAM, start at $00000
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sta $d305
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; Setup the source address. Incrementing Y will make it point to EM_COPY::OFFS.
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; We will allow page numbers higher than PAGES and map them to ROM. This will
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; allow reading the ROM by specifying a page starting with PAGES.
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iny ; EM_COPY::OFFS
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lda (ptr1),y
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sta $d300
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iny ; EM_COPY::PAGE
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lda (ptr1),y
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sta $d301
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iny
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lda (ptr1),y
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adc #START_BANK ; Carry clear here from WAIT
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and #$3f
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cmp #>PAGES+START_BANK ; Valid range?
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bcs @L1 ; Jump if no
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ora #$40 ; Address RAM
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@L1: sta $d302
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; Length
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iny ; EM_COPY::COUNT
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lda (ptr1),y
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sta $d30a
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iny
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lda (ptr1),y
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sta $d30b
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; Start DMA
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stx $d31f
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; Wait until DMA is done
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WAIT: lda $d31f
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lsr a
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bcs WAIT
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rts
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