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186 lines
3.0 KiB
ArmAsm
186 lines
3.0 KiB
ArmAsm
;
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; Atari XL shadow RAM preparation routines
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;
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; Tasks:
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; - move screen memory below load address
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; - copy shadow RAM contents to their destination
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;
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; Christian Groessler, chris@groessler.org, 2013
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;
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.if .defined(__ATARIXL__)
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.export sramprep
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.import __SRPREP_LOAD__, __SRPREP_SIZE__
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.import __SHADOW_RAM_LOAD__, __SHADOW_RAM_SIZE__
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.import __CHARGEN_LOAD__, __CHARGEN_SIZE__
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.import __SAVEAREA_LOAD__
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.include "zeropage.inc"
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.include "atari.inc"
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.include "save_area.inc"
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.macro print_string text
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.local start, cont
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jmp cont
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start: .byte text, ATEOL
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cont: ldx #0 ; channel 0
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lda #<start
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sta ICBAL,x ; address
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lda #>start
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sta ICBAH,x
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lda #<(cont - start)
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sta ICBLL,x ; length
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lda #>(cont - start)
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sta ICBLH,x
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lda #PUTCHR
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sta ICCOM,x
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jsr CIOV
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.endmacro
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; ------------------------------------------------------------------------
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; Chunk header
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.segment "SRPREPHDR"
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.word __SRPREP_LOAD__
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.word __SRPREP_LOAD__ + __SRPREP_SIZE__ - 1
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; ------------------------------------------------------------------------
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; Actual code
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.segment "SRPREP"
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sramprep:
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print_string "in sramprep"
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; save values of modified system variables and ports
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lda RAMTOP
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sta RAMTOP_save
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lda MEMTOP
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sta MEMTOP_save
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lda MEMTOP+1
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sta MEMTOP_save+1
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lda APPMHI
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sta APPMHI_save
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lda APPMHI+1
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sta APPMHI_save+1
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lda PORTB
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sta PORTB_save
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; disable BASIC
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lda PORTB
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ora #2
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sta PORTB
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; ... change memory bla
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CMPVAL = 64+255+992 ; you may ask, why these values... @@@ document
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sys_ok: lda #<__SAVEAREA_LOAD__
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sec
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sbc #<CMPVAL
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sta MEMTOP
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sta APPMHI
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lda #>__SAVEAREA_LOAD__
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sbc #>CMPVAL
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sta MEMTOP+1
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sta APPMHI+1
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lda #>__SAVEAREA_LOAD__ - 1
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sta RAMTOP
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; ... issue ar GRAPHICS 0 call (copied'n'pasted from TGI drivers)
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ldx #$50 ; take any IOCB, hopefully free (@@@ fixme)
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; Reopen it in Graphics 0
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lda #OPEN
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sta ICCOM,x
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lda #OPNIN | OPNOT
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sta ICAX1,x
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lda #0
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sta ICAX2,x
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lda #<screen_device
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sta ICBAL,x
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lda #>screen_device
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sta ICBAH,x
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lda #<screen_device_length
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sta ICBLL,x
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lda #>screen_device_length
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sta ICBLH,x
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jsr CIOV
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bpl okoko
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print_string "GR 0 FAILED"
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jsr delay
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jsr delay
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jsr delay
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jmp xxx
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okoko:
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; Now close it again; we don't need it anymore :)
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lda #CLOSE
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sta ICCOM,x
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jsr CIOV
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print_string "GR 0 OKOKO"
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jsr delay
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xxx:
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rts
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; short delay
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.proc delay
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lda #10
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l: jsr delay1
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clc
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sbc #0
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bne l
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rts
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delay1: ldx #0
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ldy #0
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loop: dey
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bne loop
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dex
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bne loop
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rts
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.endproc
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screen_device: .byte "S:",0
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screen_device_length = * - screen_device
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.byte " ** srprep ** end-->"
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; ------------------------------------------------------------------------
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; Chunk "trailer" - sets INITAD
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.segment "SRPREPTRL"
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.word INITAD
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.word INITAD+1
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.word __SRPREP_LOAD__
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.endif ; .if .defined(__ATARIXL__)
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