mirror of https://github.com/cc65/cc65.git
104 lines
2.8 KiB
ArmAsm
104 lines
2.8 KiB
ArmAsm
;
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; Pointer for library references by device drivers.
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;
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; Helper-routines for the interrupt handler that rejects bogus keypresses
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; that are caused by mouse-like devices.
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;
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; 2013-07-25, Greg King
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; 2014-04-26, Christian Groessler
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;
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.include "c128.inc"
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.export mouse_libref, _pen_adjuster
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.data
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mouse_libref: ; generic label for mouse-kernel
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; A program optionally can set this pointer to a function that gives
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; a calibration value to a driver. If this pointer isn't NULL,
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; then a driver that wants a value can call that function.
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;
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; The function might read a value from a file; or, it might ask the user
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; to help calibrate the driver.
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;
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; void __fastcall__ (*pen_adjuster)(unsigned char *) = NULL;
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;
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_pen_adjuster:
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.addr $0000
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.addr IRQStub2
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callback: ; callback into mouse driver after ROM IRQ handler has been run
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.addr $0000 ; (filled in by mouse driver)
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jmp_rom_hdlr: ; original ROM indirect IRQ handler address
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.addr $0000 ; (filled in by mouse driver)
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.segment "LOWCODE"
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; Called from irq.s when it thinks it chains to the original handler.
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; ROM is banked in again. In order to call the callback we have to
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; bank it out one more time.
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IRQStub2:
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; Call ROM handler and prepare stack so that it will return to us.
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; setup fake IRQ stack frame which will return to "IRQCont"
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lda #>@IRQCont
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pha
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lda #<@IRQCont
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pha
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php
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; mimic the contents saved on the stack by the ROM IRQ entry handler
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pha ; A
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pha ; X
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pha ; Y
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lda #MMU_CFG_CC65 ; MMU configuration which will be active after the ROM handler returns
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pha
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; map out ROM
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ldy MMU_CR
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sta MMU_CR
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; push address of ROM handler on stack and jump to it
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lda jmp_rom_hdlr+1
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pha
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lda jmp_rom_hdlr
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pha
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sty MMU_CR ; map in ROM
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rts ; jump to ROM handler
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; our MMU configuration byte we pushed on the stack before (MMU_CFG_CC65) is now active
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@IRQCont:
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; call mouse driver callback routine
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lda #>(@IRQCont2-1)
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pha
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lda #<(@IRQCont2-1)
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pha
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lda callback+1
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pha
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lda callback
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pha
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rts ; jump to callback routine
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@IRQCont2:
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; return from interrupt
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; We could just jump to $FF33, but since I don't know whether this address is valid in all
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; ROM versions, duplicate that code here.
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pla
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sta MMU_CR ; MMU configuration register
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pla
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tay
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pla
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tax
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pla
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rti
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