26 lines
656 B
ArmAsm
26 lines
656 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 296
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// - [CM64] Compute's Mapping the Commodore 64 - page 223/224
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// - https://www.pagetable.com/?p=1031, , https://github.com/mist64/cbmbus_doc
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//
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// CPU registers that has to be preserved (see [RG64]): .X, .Y
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//
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SECOND:
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// Due to OPEN/CLOSE/TKSA/SECOND command encoding (see https://www.pagetable.com/?p=1031),
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// allowed channels are 0-15; report error if out of range
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cmp #$10
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bcc !+
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jmp kernalerror_DEVICE_NOT_FOUND // XXX find a better error message for wrong channel (create new one?)
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!:
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ora #$60
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jmp common_open_close_unlsn_second
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