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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').
242 lines
7.0 KiB
ArmAsm
242 lines
7.0 KiB
ArmAsm
;
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; Extended memory driver for the Commodore REU. Driver works without
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; problems when statically linked.
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;
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; Ullrich von Bassewitz, 2002-11-29
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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 generic
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.macpack module
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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module_header _c64_reu_emd
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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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REU_STATUS = $DF00 ; Status register
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REU_COMMAND = $DF01 ; Command register
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REU_C64ADDR = $DF02 ; C64 base address register
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REU_REUADDR = $DF04 ; REU base address register
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REU_COUNT = $DF07 ; Transfer count register
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REU_IRQMASK = $DF09 ; IRQ mask register
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REU_CONTROL = $DF0A ; Control register
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REU_TRIGGER = $FF00 ; REU command trigger
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OP_COPYFROM = $ED
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OP_COPYTO = $EC
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; ------------------------------------------------------------------------
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; Data.
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.bss
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pagecount: .res 2 ; Number of pages available
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curpage: .res 2 ; Current page number
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window: .res 256 ; Memory "window"
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reu_params: .word $0000 ; Host address, lo, hi
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.word $0000 ; Exp address, lo, hi
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.byte $00 ; Expansion bank no.
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.word $0000 ; # bytes to move, lo, hi
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.byte $00 ; Interrupt mask reg.
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.byte $00 ; Adress control reg.
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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 #$00 ; High byte of return code
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lda #$55
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sta REU_REUADDR
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cmp REU_REUADDR ; Check for presence of REU
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bne nodevice
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asl a ; A = $AA
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sta REU_REUADDR
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cmp REU_REUADDR ; Check for presence of REU
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bne nodevice
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ldy #>(128*4) ; Assume 128KB
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lda REU_STATUS
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and #$10 ; Check size bit
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beq @L1
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ldy #>(256*4) ; 256KB when size bit is set
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@L1: sty pagecount+1
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ldy #$FF
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sty curpage
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sty curpage+1 ; Invalidate the current page
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txa ; X = A = EM_ERR_OK
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rts
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; No REU found
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nodevice:
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lda #EM_ERR_NO_DEVICE
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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 pagecount
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ldx pagecount+1
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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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ldy #OP_COPYFROM
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jsr common ; Copy 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
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ldx curpage+1 ; Do we have a page mapped?
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bmi done ; Jump if no page mapped
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ldy #OP_COPYTO
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common: sty tmp1
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ldy #<window
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sty REU_C64ADDR
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ldy #>window
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sty REU_C64ADDR+1
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ldy #0
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sty REU_REUADDR+0
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sta REU_REUADDR+1
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stx REU_REUADDR+2
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sty REU_COUNT+0
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ldy #1
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sty REU_COUNT+1 ; Move 256 bytes
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bne transfer1 ; Transfer 256 bytes into REU
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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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ldy #OP_COPYFROM
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.byte $2C
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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:
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ldy #OP_COPYTO
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sty tmp1
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; Remember the passed pointer
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sta ptr1
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stx ptr1+1 ; Save the pointer
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; The structure passed to the functions has the same layout as the registers
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; of the Commodore REU, so register programming is easy.
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ldy #7-1
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@L1: lda (ptr1),y
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sta REU_C64ADDR,y
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dey
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bpl @L1
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; Invalidate the page in the memory window
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sty curpage+1 ; Y = $FF
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; Reload the REU command and start the transfer
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transfer1:
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ldy tmp1
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; Transfer subroutine for the REU. Expects command in Y.
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transfer:
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sty REU_COMMAND ; Issue command
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ldy $01 ; Save the value of the c64 control port...
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tya ;
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and #$F8 ; Disable ROMs and I/O.
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sei ;
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sta $01
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lda REU_TRIGGER ; Don't change $FF00
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sta REU_TRIGGER ; Start the transfer...
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sty $01 ; Restore the old configuration
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cli
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rts
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