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2c975d3642
Up to now static drivers were created via co65 from dynamic drivers. However there was an issue with that approach: The dynamic drivers are "o65 simple files" which obligates that they start with the 'code' segment. However dynamic drivers need to start with the module header - which is written to. For dynamic drivers this isn't more than a conceptual issue because they are always contain a 'data' segment and may therefore only be loaded into writable memory. However when dynamic drivers are converted to static drivers using co65 then that issue becomes a real problem as then the 'code' segment may end up in non-writable memory - and thus writing to the module header fails. Instead of changing the way dynamic drivers work I opted to rather make static driver creation totally independent from dynamic drivers. This allows to place the module header in the 'data' segment (see 'module.mac').
246 lines
6.1 KiB
ArmAsm
246 lines
6.1 KiB
ArmAsm
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; Extended memory driver for the Apple II auxiliary memory
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;
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; Stefan Haubenthal, 2003-12-12
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; Ullrich von Bassewitz, 2002-12-02
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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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.macpack module
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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.ifdef __APPLE2ENH__
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module_header _a2e_auxmem_emd
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.else
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module_header _a2_auxmem_emd
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.endif
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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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BASE = $0200
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AUXCARD = $C30C ; Card signature
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AUXMOVE = $C311 ; Auxiliary move routine
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PAGES = ($C000 - BASE) / 256
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; ------------------------------------------------------------------------
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; Data.
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.data
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curpage: .byte $FF ; Current page number (invalid)
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.bss
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window: .res 256 ; Memory "window"
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.code
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; ------------------------------------------------------------------------
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; INSTALL routine. Is called after the driver is loaded into memory. If
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; possible, check if the hardware is present and determine the amount of
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; memory available.
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; Must return an EM_ERR_xx code in a/x.
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;
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INSTALL:
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ldx #0
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lda AUXCARD
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and #$f0
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cmp #$80
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bne @L1
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lda #EM_ERR_OK
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rts
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@L1: lda #EM_ERR_NO_DEVICE
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; rts
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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 ; Remember the new page
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clc
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adc #>BASE
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sta ptr1+1
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ldy #$00
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sty ptr1
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lda #<window
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sta ptr2
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lda #>window
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sta ptr2+1
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; Transfer one page
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clc ; Direction flag
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jsr transfer ; Transfer one page
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; Return the memory window
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lda #<window
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ldx #>window ; Return the window address
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; Done
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done: rts
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; ------------------------------------------------------------------------
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; USE: Tell the driver that the window is now associated with a given page.
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USE: sta curpage ; Remember the page
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lda #<window
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ldx #>window ; Return the window
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rts
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; ------------------------------------------------------------------------
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; COMMIT: Commit changes in the memory window to extended storage.
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COMMIT: lda curpage ; Get the current page
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cmp #$FF
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beq done ; Jump if no page mapped
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clc
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adc #>BASE
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sta ptr2+1
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ldy #$00
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sty ptr2
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lda #<window
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sta ptr1
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lda #>window
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sta ptr1+1
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lda #<$FF
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sta ptr4
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lda #>$FF
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sta ptr4+1
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sec ; Direction flag
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; Transfer one page/all bytes
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transfer:
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php
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clc
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lda ptr1
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sta $3C
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adc ptr4
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sta $3E
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lda ptr1+1
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sta $3D
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adc ptr4+1
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sta $3F
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lda ptr2
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sta $42
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lda ptr2+1
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sta $43
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plp
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jmp AUXMOVE
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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 ptr3
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stx ptr3+1 ; Save the passed em_copy pointer
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ldy #EM_COPY::OFFS
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lda (ptr3),y
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sta ptr1
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ldy #EM_COPY::PAGE
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lda (ptr3),y
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clc
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adc #>BASE
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sta ptr1+1 ; From
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ldy #EM_COPY::BUF
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lda (ptr3),y
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sta ptr2
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iny
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lda (ptr3),y
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sta ptr2+1 ; To
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clc ; Direction flag
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common: ldy #EM_COPY::COUNT
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lda (ptr3),y ; Get bytes in last page
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sta ptr4
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iny
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lda (ptr3),y ; Get number of pages
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sta ptr4+1
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jmp transfer
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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 ptr3
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stx ptr3+1 ; Save the passed em_copy pointer
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ldy #EM_COPY::OFFS
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lda (ptr3),y
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sta ptr2
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ldy #EM_COPY::PAGE
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lda (ptr3),y
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clc
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adc #>BASE
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sta ptr2+1 ; To
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ldy #EM_COPY::BUF
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lda (ptr3),y
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sta ptr1
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iny
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lda (ptr3),y
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sta ptr1+1 ; From
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sec ; Direction flag
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jmp common
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