2000-05-28 13:40:48 +00:00
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; Ullrich von Bassewitz, 10.08.1998
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;
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; int DbgIsRAM (unsigned Addr);
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;
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2013-05-09 11:56:54 +00:00
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.export _DbgIsRAM
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.import popax, return0, return1
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.importzp ptr1
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2000-05-28 13:40:48 +00:00
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_DbgIsRAM:
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2013-05-09 11:56:54 +00:00
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sta ptr1 ; Store the address
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stx ptr1+1
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2000-05-28 13:40:48 +00:00
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2013-05-09 11:56:54 +00:00
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ldy #0
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php ; Save I flag
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sei ; Disable interrupts
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2000-05-28 13:40:48 +00:00
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2013-05-09 11:56:54 +00:00
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lda (ptr1),y ; Get old value
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pha ; ...and save it
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2000-05-28 13:40:48 +00:00
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2013-05-09 11:56:54 +00:00
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ldx #3
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L1: lda TestVal,x
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jsr CheckCell
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bne L2
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dex
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bpl L1
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2000-05-28 13:40:48 +00:00
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; This seems to be RAM
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2013-05-09 11:56:54 +00:00
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pla
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sta (ptr1),y ; Restore old value
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plp ; Restore old I flag
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jmp return1
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2000-05-28 13:40:48 +00:00
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; No RAM at this address
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2013-05-09 11:56:54 +00:00
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L2: pla
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sta (ptr1),y ; Restore old value
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plp ; Restore old I flag
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jmp return0
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2000-05-28 13:40:48 +00:00
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; Check one memory cell
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CheckCell:
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2013-05-09 11:56:54 +00:00
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sta (ptr1),y
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cmp (ptr1),y ; Could we write it?
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rts
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2000-05-28 13:40:48 +00:00
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.rodata
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TestVal:
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2013-05-09 11:56:54 +00:00
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.byte $55, $AA, $33, $CC
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2000-05-28 13:40:48 +00:00
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