mirror of
https://github.com/cc65/cc65.git
synced 2024-07-06 13:29:01 +00:00
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 :-((
297 lines
7.0 KiB
ArmAsm
297 lines
7.0 KiB
ArmAsm
;
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; Extended memory driver for the RamCart 64/128KB cartridge. Driver works
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; without problems when statically linked.
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; Code is based on GEORAM code by Ullrich von Bassewitz.
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; Maciej 'YTM/Elysium' Witkowiak <ytm@elysium.pl>
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; 06,22.12.2002
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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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; ------------------------------------------------------------------------
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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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RAMC_WINDOW = $DF00 ; Address of RamCart window
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RAMC_PAGE_LO = $DE00 ; Page register low
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RAMC_PAGE_HI = $DE01 ; Page register high (only for RC128)
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; ------------------------------------------------------------------------
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; Data.
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.bss
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pagecount: .res 2 ; Number of available pages
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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 RAMC_WINDOW
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cpx RAMC_WINDOW
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bne @notpresent
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lda #0
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sta RAMC_PAGE_LO
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sta RAMC_PAGE_HI
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ldx RAMC_WINDOW
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cpx RAMC_WINDOW
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bne @notpresent
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lda #2
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sta RAMC_WINDOW
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cmp RAMC_WINDOW
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beq @cont
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cpx RAMC_WINDOW
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beq @readonly
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@cont: ldy #1
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sty RAMC_PAGE_HI
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sty RAMC_WINDOW
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dey
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sty RAMC_PAGE_HI
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iny
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cpy RAMC_WINDOW
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beq @rc64
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; we're on rc128
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ldx #>512
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bne @setsize
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@rc64: ldx #>256
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@setsize:
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lda #0
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sta pagecount
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stx pagecount+1
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lda #<EM_ERR_OK
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ldx #>EM_ERR_OK
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rts
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@notpresent:
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@readonly:
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lda #<EM_ERR_NO_DEVICE
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ldx #>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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; USE: Tell the driver that the window is now associated with a given page.
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; The RamCart cartridge does not copy but actually map the window, so USE is
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; identical to MAP.
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USE = MAP
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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 RAMC_PAGE_LO
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stx RAMC_PAGE_HI
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lda #<RAMC_WINDOW
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ldx #>RAMC_WINDOW
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; Use the RTS from COMMIT below to save a precious byte of storage
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; ------------------------------------------------------------------------
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; COMMIT: Commit changes in the memory window to extended storage.
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COMMIT: 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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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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; - tmp1 contains the low page register value
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; - tmp2 contains the high page register value
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; - X contains the page offset
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; - Y contains zero
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jmp @L5
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@L1: lda RAMC_WINDOW,x
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sta (ptr2),y
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iny
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bne @L2
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inc ptr2+1
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@L2: inx
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beq @L4
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; Bump count and repeat
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@L3: 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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rts
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; Bump page register
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@L4: inc tmp1
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bne @L5
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inc tmp2
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@L5: lda tmp1
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sta RAMC_PAGE_LO
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lda tmp2
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sta RAMC_PAGE_HI
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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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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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; - tmp1 contains the low page register value
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; - tmp2 contains the high page register value
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; - X contains the page offset
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; - Y contains zero
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jmp @L5
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@L1: lda (ptr2),y
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sta RAMC_WINDOW,x
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iny
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bne @L2
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inc ptr2+1
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@L2: inx
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beq @L4
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; Bump count and repeat
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@L3: 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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rts
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; Bump page register
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@L4: inc tmp1
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bne @L5
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inc tmp2
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@L5: lda tmp1
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sta RAMC_PAGE_LO
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lda tmp2
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sta RAMC_PAGE_HI
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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: 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: lower 6 bits in tmp1, high bits in tmp2.
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ldy #EM_COPY::PAGE+1
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lda (ptr1),y
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sta tmp2
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dey
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lda (ptr1),y
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sta tmp1
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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 X and clear Y
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ldy #EM_COPY::OFFS
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lda (ptr1),y
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tax
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ldy #$00
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; Done
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rts
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