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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').
447 lines
9.8 KiB
ArmAsm
447 lines
9.8 KiB
ArmAsm
;
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; Extended memory driver for the Double Quick Brown Box cartridge
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; Marco van den Heuvel, 2010-01-27
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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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.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_dqbb_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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BASE = $8000
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PAGES = ($C000 - BASE) / 256
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TARGETLOC = $200 ; Target location for copy/check code
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CONTROL = $DE00
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; ------------------------------------------------------------------------
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; Data.
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.proc check
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template:
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.org ::TARGETLOC ; Assemble for target location
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entry:
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lda $01
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pha
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lda #$37
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sta $01
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ldx #$14
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ldy #$90
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sty CONTROL
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lda $8000
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stx CONTROL
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cmp $8000
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bne present
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sty CONTROL
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inc $8000
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stx CONTROL
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cmp $8000
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beq present
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dec $8000
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ldy #$00
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done: pla
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sta $01
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rts
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present:
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sty CONTROL
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ldy #$01
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bne done
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.reloc
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.endproc
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.proc copy
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template:
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.org ::TARGETLOC ; Assemble for target location
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entry:
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.proc fetch
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stx CONTROL
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ldx $01
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lda #$37
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sta $01
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address := *+1 ; Patched at runtime
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lda ($00),y
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stx $01
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ldx #$90
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stx CONTROL
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rts
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.endproc
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.proc stash
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stx CONTROL
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ldx $01
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ldy #$37
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sty $01
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ldy #$00
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address := *+1 ; Patched at runtime
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sta ($00),y
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stx $01
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ldx #$90
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stx CONTROL
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rts
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.endproc
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.reloc
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.endproc
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.bss
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curpage: .res 1 ; Current page number
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window: .res 256 ; Memory "window"
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; Since the functions above are copied to $200, the current contents of this
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; memory area must be saved into backup storage. Allocate enough space.
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backup: .res .max (.sizeof (copy), .sizeof (check))
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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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sei
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jsr backup_and_setup_check_routine
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jsr check::entry
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cli
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ldx #.sizeof (check) - 1
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jsr restore_data
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cpy #$01
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beq @present
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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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lda #<EM_ERR_OK
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ldx #>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:
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sei
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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 #0
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sty ptr1
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jsr backup_and_setup_copy_routine
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ldx #<ptr1
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stx copy::fetch::address
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@L1:
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ldx #$14
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jsr copy::fetch
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ldx ptr1
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sta window,x
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inc ptr1
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bne @L1
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; Return the memory window
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jsr restore_copy_routine
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lda #<window
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ldx #>window ; Return the window address
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cli
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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:
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sei
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lda curpage ; Get the current page
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clc
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adc #>BASE
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sta ptr1+1
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ldy #0
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sty ptr1
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jsr backup_and_setup_copy_routine
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ldx #<ptr1
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stx copy::stash::address
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@L1:
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ldx ptr1
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lda window,x
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ldx #$14
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jsr copy::stash
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inc ptr1
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bne @L1
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; Return the memory window
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jsr restore_copy_routine
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cli
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rts
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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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sei
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pha
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txa
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pha
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jsr backup_and_setup_copy_routine
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pla
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tax
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pla
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jsr setup
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; Setup is:
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;
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; - ptr1 contains the struct pointer
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; - ptr2 contains the linear memory buffer
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; - ptr3 contains -(count-1)
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; - ptr4 contains the page memory buffer plus offset
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; - tmp1 contains zero (to be used for linear memory buffer offset)
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lda #<ptr4
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sta copy::fetch::address
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jmp @L3
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@L1:
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ldx #$14
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ldy #0
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jsr copy::fetch
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ldy tmp1
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sta (ptr2),y
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inc tmp1
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bne @L2
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inc ptr2+1
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@L2:
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inc ptr4
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beq @L4
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; Bump count and repeat
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@L3:
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inc ptr3
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bne @L1
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inc ptr3+1
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bne @L1
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jsr restore_copy_routine
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cli
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rts
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; Bump page register
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@L4:
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inc ptr4+1
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jmp @L3
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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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sei
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pha
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txa
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pha
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jsr backup_and_setup_copy_routine
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pla
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tax
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pla
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jsr setup
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; Setup is:
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;
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; - ptr1 contains the struct pointer
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; - ptr2 contains the linear memory buffer
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; - ptr3 contains -(count-1)
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; - ptr4 contains the page memory buffer plus offset
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; - tmp1 contains zero (to be used for linear memory buffer offset)
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lda #<ptr4
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sta copy::stash::address
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jmp @L3
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@L1:
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ldy tmp1
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lda (ptr2),y
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ldx #$14
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ldy #0
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jsr copy::stash
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inc tmp1
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bne @L2
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inc ptr2+1
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@L2:
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inc ptr4
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beq @L4
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; Bump count and repeat
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@L3:
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inc ptr3
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bne @L1
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inc ptr3+1
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bne @L1
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jsr restore_copy_routine
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cli
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rts
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; Bump page register
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@L4:
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inc ptr4+1
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jmp @L3
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; ------------------------------------------------------------------------
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; Helper function for COPYFROM and COPYTO: Store the pointer to the request
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; structure and prepare data for the copy
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setup:
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sta ptr1
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stx ptr1+1 ; Save passed pointer
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; Get the page number from the struct and adjust it so that it may be used
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; with the hardware. That is: ptr4 has the page address and page offset
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; tmp2 will hold the bank value
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ldy #EM_COPY::PAGE
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lda (ptr1),y
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clc
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adc #>BASE
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sta ptr4+1
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; Get the buffer pointer into ptr2
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ldy #EM_COPY::BUF
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lda (ptr1),y
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sta ptr2
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iny
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lda (ptr1),y
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sta ptr2+1
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; Get the count, calculate -(count-1) and store it into ptr3
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ldy #EM_COPY::COUNT
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lda (ptr1),y
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eor #$FF
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sta ptr3
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iny
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lda (ptr1),y
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eor #$FF
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sta ptr3+1
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; Get the page offset into ptr4 and clear tmp1
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ldy #EM_COPY::OFFS
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lda (ptr1),y
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sta ptr4
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lda #0
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sta tmp1
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; Done
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rts
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; Helper routines for copying to and from the +256k ram
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backup_and_setup_copy_routine:
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ldx #.sizeof (copy) - 1
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@L1:
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lda copy::entry,x
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sta backup,x
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lda copy::template,x
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sta copy::entry,x
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dex
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bpl @L1
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rts
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backup_and_setup_check_routine:
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ldx #.sizeof (check) - 1
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@L1:
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lda check::entry,x
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sta backup,x
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lda check::template,x
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sta check::entry,x
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dex
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bpl @L1
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rts
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restore_copy_routine:
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ldx #.sizeof (copy) - 1
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restore_data:
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lda backup,x
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sta TARGETLOC,x
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dex
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bpl restore_data
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rts
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