33 lines
738 B
ArmAsm
33 lines
738 B
ArmAsm
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//
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// Official Kernal routine, described in:
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//
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// - [RG64] C64 Programmer's Reference Guide - page 290
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// - [CM64] Compute's Mapping the Commodore 64 - page 215
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//
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// CPU registers that has to be preserved (see [RG64]): none
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//
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PLOT:
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bcs plot_get
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// Note: the 'set' part has to start from $E50C, as this is a known address
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// - https://www.lemon64.com/forum/viewtopic.php?t=3296&%3Bstart=15
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// - https://sys64738.org/2019/05/c64-bedtime-coding-eng-printing-08/
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// - 'Duotris' game calls $E50C during startup screen initialization
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plot_set:
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sty PNTR
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stx TBLX
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jsr screen_calculate_line_pointer
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// XXX cursor blink might need to be handled too
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// FALLTROUGH to save one byte on RTS
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plot_get:
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ldy PNTR
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ldx TBLX
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rts
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