32 lines
752 B
ArmAsm
32 lines
752 B
ArmAsm
#if ROM_LAYOUT_STD || (ROM_LAYOUT_M65 && SEGMENT_BASIC_0)
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// Well-known BASIC routine, described in:
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//
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// - [CM64] Computes Mapping the Commodore 64 - page 97
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// - https://www.c64-wiki.com/wiki/BASIC-ROM
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// - https://csdb.dk/forums/?roomid=11&topicid=137233
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//
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// XXX use this routine to initialize TXTPTR
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RUNC:
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// According to WIKI, we should load $7A/$7B with $2B-1/$2C-1), this does not makes sense.
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// But CSDB claims, that it should 'set current character pointer to start of basic - 1' - this
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// looks sane, also checked that the original BASIC routine does this (short test program)
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// Lets initialize TXTPTR using TXTTAB
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lda TXTTAB+0
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sec
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sbc #$01
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sta TXTPTR+0
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lda TXTTAB+1
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sbc #$00
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sta TXTPTR+1
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rts
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#endif // ROM layout
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